Inorganic Syntheses, Volume 37 E-Book
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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Serie: Inorganic Syntheses
- Sprache: Englisch
The newest volume in the authoritative Inorganic Syntheses book series provides users of inorganic substances with detailed and foolproof procedures for the preparation of important and timely inorganic and organometallic compounds that can be used in reactions to develop new materials, drug targets, and bio-inspired chemical entities.
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Table of Contents
COVER
PREFACE
Chapter One: DIVALENT MANGANESE, IRON, AND COBALT BIS(TRIMETHYLSILYL)AMIDO DERIVATIVES AND THEIR TETRAHYDROFURAN COMPLEXES
1. INTRODUCTION
References
2. BIS{BIS(TRIMETHYLSILYL)AMIDO}IRON(II) DIMER: [Fe{N(SiMe
3
)
2
}
2
]
2
References
3. BIS{BIS(TRIMETHYLSILYL)AMIDO}COBALT(II) DIMER, [Co{N(SiMe
3
)
2
}
2
]
2
, AND BIS{BIS(TRIMETHYLSILYL)AMIDO}(TETRAHYDROFURAN)COBALT(II), Co{N(SiMe
3
)
2
}
2
(THF)
References
4. BIS{BIS(TRIMETHYLSILYL)AMIDO}MANGANESE(II) DIMER, [Mn{N(SiMe
3
)
2
}
2
]
2
, AND ITS THF COMPLEXES Mn{N(SiMe
3
)
2
}
2
(THF) AND Mn{N(SiMe
3
)
2
}
2
(THF)
2
References
Chapter Two: CALCIUM, STRONTIUM, GERMANIUM, TIN, AND LEAD BIS(TRIMETHYLSILYL)AMIDO DERIVATIVES AND 2,2,6,6‐TETRAMETHYLPIPERIDIDO AND
N
‐ISOPROPYLPHENYLAMIDO DERVATIVES OF POTASSIUM AND CALCIUM
1. INTRODUCTION
References
2. POTASSIUM (2,2,6,6‐TETRAMETHYLPIPERIDIDE), BIS(2,2,6,6‐TETRAMETHYLPIPERIDIDO) (
N,N,N′,N′
‐TETRAMETHYLETHYLENEDIAMINE)CALCIUM(II), POTASSIUM (
N
‐ISOPROPYLANILIDO), AND BIS(
N
‐ISOPROPYLANILIDO) TRIS(TETRAHYDROFURAN)CALCIUM(II)
References
3. BIS{BIS(TRIMETHYLSILYL)AMIDO}CALCIUM(II) DIMER, [Ca{N(SiMe
3
)
2
}
2
]
2
, AND BIS{BIS(TRIMETHYLSILYL)AMIDO}STRONTIUM(II) DIMER, [Sr{N(SiMe
3
)
2
}
2
]
2
References
4. DIVALENT GROUP 14 METAL BIS(TRIMETHYLSILYLAMIDES), M{N(SiMe
3
)
2
}
2
(M = Ge, Sn, Pb)
References
Chapter Three: COMPOUNDS WITH Zn–Zn AND Mg–Mg BONDS
1. INTRODUCTION
References
2. PENTAMETHYLCYCLOPENTADIENYL ZINC(I) DIMER, {Zn(η‐C
5
Me
5
)}
2
References
3. β‐DIKETIMINATO COMPLEXES OF MAGNESIUM(I)/(II)
References
Chapter Four: STERICALLY CROWDED σ‐ AND π‐BONDED METAL ARYL COMPLEXES
1. INTRODUCTION
References
2. DIMESITYLIRON(II) DIMER AND DIMESITYLDIPYRIDINEIRON(II) (Mes = Mesityl = C
6
H
2
‐2,4,6‐Me
3
)
References
3. HOMOLEPTIC, TWO‐COORDINATE OPEN‐SHELL 2,6‐DIMESITYLPHENYL COMPLEXES OF LITHIUM, MANGANESE, IRON, AND COBALT
References
4. MONOMERIC GROUP 14 DIARYLS BIS{2,6‐BIS(2,4,6‐TRIMETHYLPHENYL)PHENYL}GERMANIUM(II), TIN(II), OR LEAD(II), M{C
6
H
3
‐2,6‐Mes
2
)
2
AND BIS{2,6‐BIS(2,6‐DIISOPROPYLPHENYL)PHENYL}GERMANIUM(II), TIN(II), OR LEAD(II), M{C
6
H
3
‐2,6‐Dipp
2
}
2
(M = Ge, Sn, or Pb; Mes = C
6
H
2
‐2,4,6‐Me
3
; Dipp = C
6
H
3
‐2,6‐Pr
2
)
References
5.
m
‐TERPHENYLGALLIUM CHLORIDE COMPLEXES
References
6. {(18‐CROWN‐6)BIS(TETRAHYDROFURAN)POTASSIUM}{BIS(1,2,3,4‐η‐ANTHRACENE)METALLATES} OF COBALT(‐I) AND IRON(‐I), {K(18‐CROWN‐6)(THF)
2
}{M(η‐C
14
H
10
)
2
}, M = Co, Fe
References
7. {BIS(1,2‐DIMETHOXYETHANE)POTASSIUM}{BIS(1,2,3,4‐η‐ANTHRACENE)COBALTATE}, {K(DME)
2
}{Co(η‐C
14
H
10
)
2
}
References
8. CYCLOPENTADIENYL AND PENTAMETHYLCYCLOPENTADIENYL NAPHTHALENE FERRATES
References
Chapter Five: TERPHENYL LIGANDS AND COMPLEXES
1. INTRODUCTION
References
2.
m
‐TERPHENYL IODO AND LITHIUM REAGENTS FEATURING 2,6‐BIS‐(2,6‐DIISOPROPYLPHENYL) SUBSTITUTION PATTERNS AND AN
m
‐TERPHENYL LITHIUM ETHERATE FEATURING THE 2,6‐BIS‐(2,4,6‐TRIISOPROPYLPHENYL) SUBSTITUTION PATTERN
References
3. 2,6‐DIMESITYLANILINE (H
2
NC
6
H
3
‐2,6‐Mes
2
) AND 2,6‐BIS(2,4,6‐TRIISOPROPYLPHENYL)ANILINE (H
2
NC
6
H
3
‐2,6‐Trip
2
)
References
4. BIS‐2,6‐(2,6‐DIISOPROPYLPHENYL)ANILINE
References
5. BIS‐2,6‐(2,4,6‐TRIMETHYLPHENYL)PHENYLFORMAMIDE AND ISOCYANIDE, BIS‐2,6‐(2,6‐DIISOPROPYLPHENYL)PHENYLFORMAMIDE AND ISOCYANIDE
References
6. SYNTHESIS OF THE TERPHENYLTHIOLS: 2,6‐BIS(2,6‐DIISOPROPYLPHENYL)PHENYLTHIOL, 2,6‐BIS(2,4,6‐TRIISOPROPYLPHENYL)PHENYLTHIOL, AND BIS{2,6‐BIS(2,4,6‐TRIISOPROPYLPHENYL)PHENYLTHIOLATO}DILITHIUM
References
7. STERICALLY ENCUMBERED TERPHENOLS: 2,6‐BIS(2,4,6‐TRIMETHYLPHENYL)PHENOL AND 2,6‐BIS(2,6‐DIISOPROPYLPHENYL)PHENOL
References
Chapter Six: SYNTHETIC ROUTE TO WHITE PHOSPHORUS (P
4
) AND ARSENIC TRIPHOSPHIDE (AsP
3
)
1. INTRODUCTION
References
2. FACILE PREPARATION OF WHITE PHOSPHORUS FROM RED PHOSPHORUS: PREPARATION A
References
3. SYNTHESIS OF WHITE PHOSPHORUS (P
4
) FROM RED PHOSPHORUS: PREPARATION B
References
4. ARSENIC TRIPHOSPHIDE, AsP
3
References
Chapter Seven: SYNTHETIC ROUTES TO PHOSPHIDO AND ARSENIDO DERIVATIVES OF THE GROUP 13 METALS ALUMINUM, GALLIUM, AND INDIUM, TRIS(TERT‐BUTYL)GALLIUM AND ITS REACTIONS WITH AMMONIA, AND THE ALUMINUM(I) SPECIES PENTAMETHYLCYCLOPENTADIENYL ALUMINUM TETRAMER
1. INTRODUCTION
References
2. DINUCLEAR PHOSPHIDO AND ARSENIDO DERIVATIVES OF ALUMINUM, GALLIUM, AND INDIUM {Me
2
M(μ‐EBu
2
)}
2
, M = Al, Ga, In; E = P, AS
References
3. TRIS(TERT‐BUTYL)GALLANE, ITS AMMONIA COMPLEX, AND THE AMIDOBIS(TERT‐BUTYL)GALLANE TRIMER TRIS(μ‐AMIDO)HEXA(TERT‐BUTYL) TRIGALLIUM
References
4. REDUCTIVE ELIMINATION AS A CONVENIENT PATHWAY TO TETRAMERIC (η‐PENTAMETHYLCYCLOPENTADIENYL)ALUMINUM(I) {(AlCp)
4
} (Cp = η‐C
5
Me
5
)
References
5. A FACILE SYNTHESIS OF TETRAMERIC (ƞ‐PENTAMETHYLYCYCLOCLOPENTADIENYL)ALUMINUM(I) {Al(ƞ‐C
5
Me
5
)}
4
References
6. TRIS(PENTAFLUOROPHENYL)ALUMINUM(TOLUENE): Al(C
6
F
5
)
3
(C
7
H
8
)
References
Chapter Eight: SYNTHESIS OF SELECTED TRANSITION METAL AND MAIN GROUP COMPOUNDS WITH SYNTHETIC APPLICATIONS
1. INTRODUCTION
References
2. SYNTHESIS OF GOLD(I) AND GOLD(II) AMIDINATE COMPLEXES
References
3. A NICKEL–IRON THIOLATE AND ITS HYDRIDE
References
4. DIMETHYL SULFOXIDE AND ORGANOPHOSPHINE COMPLEXES OF RUTHENIUM(II) HALIDES
References
5. SYNTHESIS OF {Cr(NCMe)
6
}(BF
4
)
3
AND {Cr(NCMe)
5
F}(BF
4
)
2
•MeCN
References
6. (1
R
,2
R
‐DIAMINOCYCLOHEXANE)OXALATOPLATINUM(II), OXALIPLATIN
References
7. TRIS(DIBENZYLIDENEACETONE)DIPALLADIUM(0)
References
8. TETRAALKYLAMMONIUM SALTS OF TETRA(FLUOROARYL)BORATE ANIONS
References
9. TITANIUM TRIS(
N
‐
tert
‐BUTYL, 3,5‐DIMETHYLANILIDE)
References
10. TETRACHLORIDO(TETRAMETHYLETHYLENEDIAMINE)TANTALUM(IV), TaCl
4
(TMEDA)
References
11. SYNTHESIS OF 1,3,5‐TRI‐
tert
‐BUTYLCYCLOPENTA‐1,3‐DIENE AND ITS METAL COMPLEXES Na{1,2,4‐(Me
3
C)
3
C
5
H
2
} AND Mg{η‐1,2,4‐(Me
3
C)
3
C
5
H
2
}
2
References
CUMULATIVE CONTRIBUTOR INDEXVOLUMES 31–37
CUMULATIVE SUBJECT INDEXVOLUMES 31–37
CUMULATIVE FORMULA INDEXVOLUMES 31–37
END USER LICENSE AGREEMENT
List of Tables
Chapter 08
Table 1. Estimated solubility data for Pd
2
dba
3
·CHCl
3
complex.
Table 2. Estimation of stability of Pd
2
dba
3
·CHCl
3
and decomposition in the solid state and in solution.
List of Illustrations
Chapter 04
Figure 1.
1
H NMR spectrum of {K(DME)
2
}{Co(η
4
‐C
14
H
10
)
2
} (400.13 MHz, THF‐
d
8
, 300 K); signals marked with * correspond to unidentified impurity.
Figure 2.
13
C{
1
H} NMR spectrum of {K(DME)
2
}{Co(η
4
‐C
14
H
10
)
2
} (100.61 MHz, THF‐
d
8
, 300 K).
Figure 1.
1
H NMR spectrum of [{Li(THF)
2
}{CpFe(η
4
‐C
10
H
8
)}] (300.13 MHz, 293 K, C
6
D
6
); the signal marked with * corresponds to free naphthalene due to decomposition; the signal marked with # corresponds to silicon grease.
Figure 2.
13
C{
1
H} NMR spectrum of {Li(THF)
2
}{CpFe(η
4
‐C
10
H
8
} (100.61 MHz, 300 K, C
6
D
6
).
Figure 3.
1
H NMR spectrum of [{K(18‐crown‐6)}{Cp*Fe(η
4
‐C
10
H
8
)}] (400.13 MHz, 233 K, THF‐
d
8
).
Figure 4.
13
C{
1
H} NMR spectrum of [{K(18‐crown‐6)}{Cp*Fe(η
4
‐C
10
H
8
)}] (100.61 MHz, 233 K, THF‐
d
8
).
Chapter 05
Scheme 1. Drawings of the three bulky terphenyl substituents employed in compounds that are in this chapter, illustrating the wedge‐shaped space between the flanking aryl rings.
Scheme 2. A one‐pot synthesis of the terphenyl iodide 1‐I‐2,6‐Ar
2
C
6
H
3
.
5
Scheme 3. The shorter, one‐pot synthetic route to a terphenyl iodide 1‐I‐2,6‐Ar
2
C
6
H
3.
6, 7
Chapter 06
Scheme 1. Synthetic scheme for AsP
3
.
Figure 1. Design ((a) top view, (b) side view) for the preparation of white phosphorus from red phosphorus.
Figure 1. Picture of the Chemglass sublimation apparatus
Figure 2.
31
P NMR spectrum for white phosphorus (C
6
D
6
, 293 K, 162 MHz).
Chapter 08
Figure 1. Synthesis of the amidine ligands.
Figure 2. Schematic representation of the formation trinuclear and dinuclear gold(I) amidinate complexes.
Figure 3. Schematic representation of the reaction between amidinate ligands and Au(THT)Cl.
Figure 4. Oxidative addition to the dinuclear gold(I) amidinate.
Scheme 1. Substitution of dba ligands in Pd
2
dba
3
in solution.
Figure 1.
1
H NMR spectrum of Pd
2
dba
3
:dba mixture (600 MHz, CDCl
3
, r.t.).
Guide
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Board of Directors
GREGORY S. GIROLAMI, President University of Illinois at Urbana‐ChampaignALFRED P. SATTELBERGER, Treasurer Argonne National LaboratorySTOSH A. KOZIMOR Los Alamos National LaboratoryPHILIP P. POWER University of California at DavisTHOMAS B. RAUCHFUSS University of Illinois at Urbana‐ChampaignCHRISTINE M. THOMAS Brandeis University
Secretary to the Corporation
STANTON S. CHING Connecticut College
Future Volumes
38 TBA
Editor‐in‐Chief
PHILIP P. POWER
University of California at Davis
INORGANIC SYNTHESES
Volume 37
This edition first published 2018© 2018 John Wiley & Sons, Inc.
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Library of Congress Catalog Number: 39:23015
ISBN: 978-1-119-47773-0
DEDICATION
This volume is dedicated to the memory of Donald C. Bradley, Malcolm H. Chisholm, Michael F. Lappert, and Sheldon G. Shore, four giants in synthetic inorganic chemistry.
PHILIP P. POWER
University of California, Davis, CA
NOTE TO CONTRIBUTORS AND CHECKERS
The Inorganic Syntheses series (www.inorgsynth.com) publishes detailed and independently checked procedures for making important inorganic and organometallic compounds. Thus, the series is the concern of the entire scientific community. The Editorial Board hopes that many chemists will share in the responsibility of producing Inorganic Syntheses by offering their advice and assistance in both the formulation and the laboratory evaluation of outstanding syntheses.
The major criterion by which syntheses are judged is their potential value to the scientific community. We hope that the syntheses will be widely used and provide access to a broad range of compounds of importance in current research. The syntheses represent the best available procedures, and new or improved syntheses of well‐established compounds are often featured. Syntheses of compounds that are available commercially at reasonable prices are ordinarily not included, however, unless the procedure illustrates some useful technique. Inorganic Syntheses is not a repository of primary research data, and therefore submitted syntheses should have already appeared in some form in the primary peer‐reviewed literature and, at least to some extent, passed the “test of time.” The series offers authors the chance to describe the intricacies of synthesis and purification in greater detail than possible in the original literature, as well as to provide updates of an established synthesis.
Authors wishing to submit syntheses for possible publication should write their manuscripts in a style that conforms with that of previous volumes of Inorganic Syntheses (a style guide is available from the Board Secretary). The manuscript should be in English and submitted as an editable electronic document. Nomenclature should be consistent and should follow the recommendations presented in Nomenclature of Inorganic Chemistry, IUPAC Recommendations 2005, published for the International Union of Pure and Applied Chemistry by the Royal Society of Chemistry, Cambridge, 2005. This document is available online (as of 2012) at http://www.iupac.org/fileadmin/user_upload/databases/Red_Book_2005.pdf. Abbreviations should conform to those used in publications of the American Chemical Society, particularly Inorganic Chemistry.
Submissions should consist of four sections: Introduction, Procedure, Properties, and References. The Introduction should include an indication of the importance and utility of the product(s) in question and a concise and critical summary of the available procedures for making them and what advantage(s) the chosen method has over the alternatives. The Procedure should present detailed and unambiguous laboratory directions and be written so that it anticipates possible mistakes and misunderstandings on the part of the person who attempts to duplicate the procedure. It should contain an admonition if any potential hazards are associated with the procedure and what safety precautions should be taken. Sources of unusual starting materials must be given, and, if possible, minimal standards of purity of reagents and solvents should be stated. Ideally, all reagents are readily available commercially or have been described in earlier volumes of Inorganic Syntheses. The scale should be reasonable for normal laboratory operation, and problems involved in scaling the procedure either up or down should be discussed if known. Unusual equipment or procedures should be clearly described and, if necessary for clarity, illustrated in line drawings. The yield should be given both in mass and in percentage based on theory. The Procedure section normally will conclude with calculated and found microanalytical data. The Properties section should supply and discuss those physical and chemical characteristics that are relevant to judging the purity of the product and to permitting its handling and use in an intelligent manner. Under References, pertinent literature citations should be listed in the order they appear in the text.
Manuscripts should be submitted electronically to the Secretary of the Editorial Board, Professor Stanton Ching ([email protected]). The Editorial Board determines whether submitted syntheses meet the general specifications outlined above. Every procedure will be checked in an independent laboratory, and publication is contingent on satisfactory duplication of the syntheses. For online access to information and requirements, see www.inorgsynth.com.
Chemists willing to check syntheses should contact the editor of a future volume or make this information known to Professor Ching.
Volume 36 included two different preparations of tungsten oxotetrachloride, WOCl4. These preparations were originally described in the following two papers, which should have been cited: H.‐J. Lunk and W. Petke, Z. Chem. 14, 365 (1974) and V. C. Gibson, T. P. Kee, and A. Shaw, Polyhedron 7, 579 (1988). In addition, because the tungsten content of WOCl4 samples is less sensitive to the presence of impurities, it is best to assess purity by means of a chloride microanalysis: Calcd. Cl, 41.5%. We thank Dr. Lunk for bringing this information to our attention.
TOXIC SUBSTANCES AND LABORATORY HAZARDS
Chemicals and chemistry are by their very nature hazardous. All reasonable care should be taken to avoid inhalation or other physical contact with reagents and solvents used in this volume. In addition, particular attention should be paid to avoiding sparks, open flames, or other potential sources that could set fire to combustible vapors or gases. The specific hazards in the syntheses reported in this volume are delineated, where appropriate, in the experimental procedure. It is impossible, however, to foresee every eventuality, such as a new biological effect of a common laboratory reagent. As a consequence, all chemicals used and all reactions described in this volume should be viewed as potentially hazardous.
The following sources are recommended for guidance:
NIOSH Pocket Guide to Chemical Hazards
, US Government Printing Office, Washington, DC, 2005 (ISBN‐13: 978‐1‐59804‐052‐4), is available free at
http://www.cdc.gov/niosh/npg/and
can be purchased in paperback and spiral bound format. It contains information and data for 677 common compounds and classes of compounds.
Organic Syntheses
, which is available online at
http://www.orgsyn.org
, has a concise but useful section “Handling Hazardous Chemicals.”
Prudent Practices in the Laboratory: Handling and Disposal of Chemicals
, National Academy Press, 1995 (ISBN‐13: 978‐0‐30905‐229‐0), is available free at
http://www.nap.edu/catalog.php?record_id=4911
.
Amarego, W.L.F. and Chai, C. (2009).
Purification of Laboratory Chemicals
, 6e. Oxford: Butterworth‐Heinemann, (ISBN‐13: 978‐1‐85617‐567‐8), is the standard reference for the purification of reagents and solvents. Special attention should be paid to the purification and storage of ethers.
PREFACE
This volume of Inorganic Syntheses presents detailed descriptions of the synthesis of more than one hundred compounds drawn from the main group and transition metal elements. More than half of the compounds have been chosen mainly for their synthetic utility, that is to say, they can serve as synthons by simple procedures for a wide range of other compounds. The bis(trimethylsilyl)amido derivatives of manganese, iron, cobalt, or the group 2 or 14 elements are prominent examples of such synthons. In addition, these amides are inexpensive and relatively easily prepared. Furthermore, they are highly useful hydrocarbon‐soluble sources of their masked divalent metal ions.
A further prominent theme in this volume is the synthesis of sterically crowding ligands that have enabled the isolation of species with unusual coordination numbers and multiple bonding. These are exemplified by the terphenyl ligands, which feature a central aryl ring bound to two flanking aryl rings at the ortho positions. The latter rings are further substituted by alkyl groups, thus creating a sterically protected area around the element to which the terphenyl is attached. These terphenyl ligands also bear a steric resemblance to β‐diketiminate or Nacnac ligands that carry aryl groups at their nitrogen atoms and were the subject of a large chapter (Chapter 1) of Volume 35 of Inorganic Syntheses.
A noteworthy inclusion in this volume is the syntheses of species having the first stable well‐characterized examples of magnesium–magnesium and zinc─zinc bonds. These provide a striking illustration of how compounds of a completely new class with unprecedented bonding can be synthesized by relatively straightforward routes using readily accessible ligands, i.e. the abovementioned β‐diketiminate and the well‐known pentamethylcyclopentadienyl ligands.
This volume is organized into eight chapters. Some background and historical perspective are provided in the introduction to each chapter. The opening chapter describes the synthesis and characterization data for the above‐mentioned divalent transition metal silylamides [M{N(SiMe3)2}2]2 (M = Mn, Fe, and Co) and their tetrahydrofuran complexes. The silylamide theme is continued in Chapter 2, where the synthesis of the group 2 compounds [M{N(SiMe3)2}2]2 (M = Ca and Sr) and the monomeric group 14 derivatives M{N(SiMe3)2}2 (M = Ge, Sn, or Pb) are detailed. In addition, the synthesis of some 2,2,6,6‐tetramethylpiperidido and N(Pri) anilido salts of potassium or calcium are described.
The preparations of the abovementioned groundbreaking metal–metal bonded (η5‐C5Me5)ZnZn(η5‐C5Me5) and NacnacMgMgNacnac complexes are the subject of Chapter 3. Chapter 4 features the synthesis of several sterically crowded main group and transition metal organometallic complexes. These include the simple dimeric, divalent diaryl (FeMes2)2 (Mes = C6H2‐2,4,6‐Me3), and the monomeric bisterphenyl derivatives M(C6H3‐2,6‐Mes2)2 (M = Mn, Fe, and Co). Included also are the syntheses of the precursor iodo and lithium derivatives. Similarly, the bent, highly colored group 14 element congeners M(C6H3‐2,6‐Mes2)2 (M = Ge, Sn, or Pb) are delineated. In addition, the synthesis of the related terphenyl gallium species as well as η4‐bonded bisanthracene anionic complexes of iron and cobalt is given.
In Chapter 5, the syntheses of 20 sterically crowded terphenyl compounds are detailed. These include preparations featuring the terphenyl groups ─C6H3‐2,6‐Mes2, ─C6H3‐2,6‐Dipp2 (Dipp = 2,6‐di‐iso‐propylphenyl), and ─C6H3‐2,6‐Trip2 (Trip = 2,4,6‐tri‐iso‐propylphenyl), which include the preparations of their iodo precursors, their lithium salts, azide, aniline, phenol, thiol, and isocyanide derivatives. These derivatives have proven extremely useful in supporting an extensive chemistry of compounds from the s, p, d, and f blocks of the periodic table.
In Chapter 6, the isolation of white phosphorus from red phosphorus is given by two methods involving the thermolysis of commercially available red phosphorus. In addition, the synthesis of the unusual species AsP3 from a niobium triphosphide and arsenic trihalide is described. Chapter 7 focuses on the synthesis of various unusual group 13 element derivatives. The synthesis of the pioneering aluminum(I) compound {Al(η5‐C5Me5)}4 by two approaches is described, as is that of the unusual Al(C6F5)3∙toluene complex. In addition, the synthesis of various organometallic group 13–15 compounds of relevance to materials chemistry is given.
The final chapter describes the synthesis of a variety of compounds – mainly derivatives of transition metals – that do not fit conveniently into the themes of the earlier chapters. Examples include the (1R,2R‐diaminocyclohexane)oxalatoplatinum(II) or oxaliplatin, which is marketed as the colorectal anticancer drug Eloxatin, the palladium complex tris(dibenzylideneacetone)dipalladium(II), and a series of gold(I) and (II) amidinate complexes. In addition, there are syntheses of chromium(III) acetonitrile complexes, as well as a series of ruthenium dimethylsulfoxide derivatives. From the early transition metal groups, there are the titanium(III) amide tris{(N‐tert‐butyl)(3,5‐dimethylanilido)titanium(III) and the useful tantalum(IV) complex TaCl4(tmeda). The chapter is completed by the synthesis of 1,3,5‐tri‐tert‐butylcyclopentadiene and its sodium and magnesium salts and of a series of tetraalkylammonium salts of tetrafluoroborate and fluoroarylborate salts.
The editor thanks the many (>140!) authors and checkers who contributed to this volume for their hard work and patience. In addition, many other people have helped to bring this volume to completion. Not the least among these are the editor’s undergraduate and graduate coworkers, who contributed greatly to expediting the submission and checking of various syntheses. In addition, the editor gratefully acknowledges the huge contribution of his assistant William Angel for maintaining the organization of the volume as well as the performance of numerous tasks associated with bringing the preparations to a state where they could be submitted to the printer. The editor also thanks Tom Rauchfuss, Greg Girolami, and Al Sattelberger for frequent advice and encouragement.
PHILIP P. POWER
University of California at Davis
Chapter OneDIVALENT MANGANESE, IRON, AND COBALT BIS(TRIMETHYLSILYL)AMIDO DERIVATIVES AND THEIR TETRAHYDROFURAN COMPLEXES
1. INTRODUCTION
The intention of this chapter is to describe in detail reliable synthetic procedures for the uncomplexed metal bissilylamides M{N(SiMe3)2}2 (M = Mn, Fe, or Co) as well as those of their mono‐tetrahydrofuran complexes M{N(SiMe3)2}2(THF). In addition, a synthesis for the bis(THF) complex Mn{N(SiMe3)2}2(THF)2 is given.
The bis(trimethylsilyl)amido group {N(SiMe3)2}−1, 2 is one of the simplest, most versatile, and inexpensive bulky monodentate ligands. Its steric properties were first demonstrated by Bürger and Wannagat via the synthesis of several low‐ (i.e. two‐ or three‐) coordinate transition metal derivatives in the early 1960s. They were prepared by the simple reaction of an alkali metal salt of the amide {N(SiMe3)2}− with chromium, manganese, iron, cobalt, nickel, or copper halides.1–4 The list of new compounds3, 4 included the trivalent complexes M{N(SiMe3)2}3 (M = Cr and Fe), the divalent species M{N(SiMe3)2}2 (M = Mn,4 Co,3 and Ni4 (unstable)), and the monovalent Cu{N(SiMe3)2}.4 The volatility of M(II) and M(III) derivatives supported the notion that the compounds had unassociated molecular structures and were therefore the first stable examples of open‐shell (i.e. d1–d9) transition metal complexes with coordination numbers less than four. The closed‐shell (d10) Cu(I) derivative, although volatile, proved to be tetrameric {CuN(SiMe3)2}4 with four coppers arranged in a planar array and bridged by silylamido ligands5. The trigonal planar coordination of the M(III) species was proven for Fe{N(SiMe3)2}3 via a determination of its crystal structure by Bradley, Hursthouse, and Rodesiler in 1969.6 It was shown subsequently that the –N(SiMe3)2 ligand could stabilize three coordination in most of the first‐row transition metals,7–9 lanthanide,9, 10 and some actinide metals.11, 12
The original divalent transition metal silylamides M{N(SiMe3)2}2 (M = Mn, Co, and Ni) were later expanded to include the iron analogue Fe{N(SiMe3)2}2 by Andersen, Lappert, Haaland, and coworkers in 1988.13 With the exception of the Ni species, which is unstable, the M{N(SiMe3)2}2 (M = Mn, Fe, or Co) complexes were shown to have a linear N–M–N structure in the vapor phase by gas electron diffraction in 1988,13 in agreement with the original formulation of Bürger and Wannagat.3, 4 Nonetheless, in 1978 it had been shown by Bradley, Hursthouse, and coworkers that the originally reported synthesis of Mn{N(SiMe3)2}2,4 which was carried out in tetrahydrofuran, probably described its tetrahydrofuran complex Mn{N(SiMe3)2}2(THF), which could be distilled several times without losing the tetrahydrofuran ligand.14 This view was supported by an exhaustive study of the manganese(II) silylamides by Horvath in 1979.15 Despite a 1971 paper16 that seemed to confirm the monomeric, THF‐free character of Co{N(SiMe3)2}2 (synthesized by the original Bürger and Wannagat route),3 recent work has shown that the synthesis of the silylamides of both cobalt17–19 and nickel20 in tetrahydrofuran also yielded the mono‐tetrahydrofuran complexes M{N(SiMe3)2}2(THF) (M = Co or Ni), which could be distilled directly from the reaction mixture. In addition, it had also been shown in 1991 that the synthesis of Fe{N(SiMe3)2}2 could yield Fe{N(SiMe3)2}2(THF) when carried out in tetrahydrofuran.21 The mono‐tetrahydrofuran complexes of the iron and cobalt silylamides are also obtainable by recrystallization of the uncomplexed M{N(SiMe3)2}2 (M = Fe or Co) from tetrahydrofuran. However, for Mn{N(SiMe3)2}2, the recrystallization from tetrahydrofuran produces the bis tetrahydrofuran complex Mn{N(SiMe)2}2(THF)2.21
In essence, the improved synthetic characterization methods and readily available crystal handling techniques for X‐ray crystallographic studies available to modern workers have permitted all of Bürger and Wannagat’s originally reported metal bis silylamido compounds to be unambiguously characterized. This work7, 14, 15, 17–20 has shown conclusively that these original divalent compounds are not two‐coordinate species, but are in fact the tetrahydrofuran complexes M{N(SiMe3)2}2(THF) (M = Mn, Co, and Ni). For these mono‐tetrahydrofuran species and their later synthesized iron analogue Fe{N(SiMe3)2}2(THF), the complexed tetrahydrofuran can only be removed with difficulty. For example, the desolvation of Mn{N(SiMe3)2}2(THF) requires heating at 120 °C under argon for 1 h.
The pure tetrahydrofuran‐free amides “M{N(SiMe3)2}2” (M = Mn, Fe, Co) can be synthesized by performing the synthesis in diethyl ether, which does not bind to the metal as strongly as tetrahydrofuran and is easily removed. They are monomers in the vapor phase,13 but they are crystalline solids at room temperature with amido‐bridged dimeric structures and three‐coordinate metals as shown by X‐ray crystallography.17, 21–24 Variable temperature 1H NMR studies of their solutions17, 21 have shown that the monomeric and dimeric structures exist in equilibrium with relatively low association energies, so that the major portion of the species present in their solutions consists of the monomers.
An interesting aspect of more than a half‐century of work on the compounds is the length of time that was required for the distinction between the bright green Co{N(SiMe3)2}2(THF) and [Co{N(SiMe3)2}2]2 (red/olive) to be delineated. A clear distinction between the two compounds was, in fact, specifically described only in 2013.17, 18 This lengthy period is particularly noteworthy in view of the very sharp contrast between the colors of the two compounds that makes them easily distinguishable. In contrast, the colors of the THF‐free and THF‐complexed amide for each of the metals Mn, Fe, and Ni are similar, which does not allow for easy visual distinction. This author and his group had used [Co{N(SiMe3)2}2]2 (synthesized in diethyl ether solvent) numerous times as a synthon9, 23 over a 30‐year period, and had in fact characterized it structurally using X‐ray crystallography in 1984,24 but he saw the bright green crystals of Co{N(SiMe3)2}2(THF) for the first time (synthesized by graduate student A. M. Bryan) in the fall of 2012.25 One reason for this strange circumstance is that the original Bürger and Wannagat synthetic procedures were all carried out in tetrahydrofuran. This solvent is less commonly used in this author’s lab, owing to the general avoidance of the use of tetrahydrofuran as a solvent if diethyl ether suffices. The Co{N(SiMe3)2}2(THF) complex was “rediscovered” recently because the magnetic properties17, 19, 26–28 of two‐ and three‐coordinate cobalt complexes, which generally have high orbital magnetism, were being investigated and because of a need for well‐defined cobalt precursor complexes in materials chemistry.18
References
1. The ligand is obtained by deprotonation of HN(SiMe
3
)
2
, itself synthesized via the reaction of ammonia with Me
3
SiCl: R. O. Sauer,
J. Am. Chem. Soc.
66
, 1707–1710 (1944).
2. For an account of the s‐metal salts of the –N(SiMe
3
)
2
ligand, see M. P. Coles,
Coord. Chem. Rev.
297–298
, 2–23 (2015).
3. H. Bürger and U. Wannagat,
Monatsh. Chem.
94
, 1007–1012 (1963).
4. H. Bürger and U. Wannagat,
Monatsh. Chem.
95
, 1099–1102 (1964).
5. A. M. James, R. K. Laxman, F. R. Fronczek, and A. W. Maverick,
Inorg. Chem.
37
, 3785–3791 (1998).
6. (a) D. C. Bradley, M. B. Hursthouse, and P. F. Rodesiler,
J. Chem. Soc. D., Chem. Commun.
14–15 (1969); (b) M. B. Hursthouse and P. F. Rodesiler,
J. Chem. Soc., Dalton Trans
. 2100–2102 (1972).
7. P. G. Eller, D. C. Bradley, M. B. Hursthouse, and D. W. Meek,
Coord. Chem. Rev.
24
, 1–95 (1977).
8. C. C. Cummins,
Prog. Inorg. Chem.
47
, 685–836 (1998).
9. M. F. Lappert, P. P. Power, A. Protchenko, and A. Seeber,
Metal Amide Chemistry
, Wiley, Chichester, 2009.
10. J. S. Ghotra, M. B. Hursthouse, and A. J. Welch,
Chem. Commun.
669–670 (1973).
11. R. A. Andersen,
Inorg. Chem.
18
, 1507–1509 (1979).
12. L. R. Avens, S. G. Bott, D. L. Clark, A. P. Sattelberger, J. G. Watson, and B. D. Zwick,
Inorg. Chem.
33
, 2248–2256 (1994).
13. R. A. Andersen, K. Faegri, J. C. Green, A. Haaland, M. F. Lappert, W.‐P. Leung, and K. Rypdal,
Inorg. Chem.
27
, 1782–1786 (1988).
14. D. C. Bradley, M. B. Hursthouse, K. M. Abdul Malik, and R. Möseler,
Transition Met. Chem.
3
, 253–254 (1978).
15. B. Horvath, R. Möseler, and E. G. Horvath,
Z. Anorg. Allg. Chem.
450
, 165–177 (1979).
16. D. C. Bradley and K. J. Fisher,
J. Am. Chem. Soc.
93
, 2058–2059 (1971).
17. A. M. Bryan, G. J. Long, F. Grandjean, and P. P. Power,
Inorg. Chem.
52
, 12152–12160 (2013).
18. B. Cormary, F. Dumestre, N. Liakakos, K. Soulantica, and B. Chaudret,
Dalton Trans.
42
, 12546–12553 (2013).
19. A. Eichhöfer, Y. Lan, V. Mereacre, T. Bodenstein, and F. Weigend,
Inorg. Chem.
53
, 1962–1974 (2014).
20. M. Faust, A. M. Bryan, A. Mansikkamäki, P. Vasko, M. M. Olmstead, H. M. Tuononen, and P. P. Power,
Angew. Chem. Int. Ed.
54
, 12914–12917 (2015).
21. M. M. Olmstead, P. P. Power, and S. C. Shoner,
Inorg. Chem.
30
, 2547–2551 (1991).
22. D. C. Bradley, M. B. Hursthouse, A. A. Ibrahim, K. M. Abdul Malik, M. Motevalli, R. Möseler, H. Powell, J. D. Runnacles, and A. C. Sullivan,
Polyhedron
19
, 2959–2964 (1990).
23. P. P. Power,
Chemtracts ‐ Inorg. Chem.
6
, 181–195 (1994).
24. B. D. Murray and P. P. Power,
Inorg. Chem.
23
, 4594–4588 (1984).
25. Photographs of crystals of [Co{N(SiMe
3
)
2
}
2
]
2
, Co{N(SiMe
3
)
2
}
2
(THF), and some other three coordinate Co(II) species are illustrated in the Supplementary Information of Reference 17.
26. R. A. Layfield,
Organometallics
33
, 1084–1099 (2014).
27. B. M. Day, K. Pal, T. Pugh, J. Tuck, and R. A. Layfield,
Inorg. Chem.
53
, 10578–10584 (2014).
28. A. Massart, P. Braunstein, A. D. Danopoulos, S. Choua, and P. Rabu,
Organometallics
34
, 2429–2438 (2015).
2. BIS{BIS(TRIMETHYLSILYL)AMIDO}IRON(II) DIMER: [Fe{N(SiMe3)2}2]2
Submitted by RICHARD A. ANDERSEN*
Checked by AIMEE M. BRYAN,† MICHELLE FAUST,† and PHILIP P. POWER†
*Department of Chemistry, University of California, Berkeley, CA 94720
†Department of Chemistry, University of California, Davis, CA 95616
The hydrocarbon‐soluble ironsilylamide, Fe{N(SiMe3)2}2,1 is a useful starting material for the synthesis of inorganic, coordination, and organometallic compounds utilizing proton‐transfer reactions, since the pKa of HN(SiMe3)2 is approximately 26 in THF.2 A comprehensive description of the compounds that may be prepared using this methodology is available in an exhaustive review of two‐coordinate compounds.3 The silylamide is a useful precursor for solid‐state materials4 and catalysts.5 The synthesis of Fe{N(SiMe3)2}2 has been described in an earlier volume6 of this series. Here we provide related syntheses by two routes and provide details of its electronic, mass, IR, and electronic spectra.
General Procedures
All reactions are performed under an atmosphere of nitrogen. Ether solvents are distilled from sodium–benzophenone and hydrocarbons are distilled from sodium under an atmosphere of nitrogen. It is important that the distillation of Fe{N(SiMe3)2}2 is carried out in an all‐glass distillation apparatus directly connected to a diffusion‐pump vacuum system with greased, ground‐glass joints. The FeBr2(THF)2 is obtained by Soxhlet extraction of anhydrous FeBr2 with THF as described in the literature.7 The ratio of THF to FeBr2 is determined by combustion analysis or hydrolysis of a known mass suspended in C6D6 containing a reference, such as ferrocene, with D2O in a NMR tube and integrating the resulting 1H NMR spectrum. Crystalline LiN(SiMe3)2(0.80 Et2O) is prepared by dropwise addition of HN(SiMe3)2 in diethyl ether to n‐butyllithium in hexane in a 1 : 1 molar ratio at 0 °C followed by crystallization by cooling a concentrated solution to −20 °C. The ratio of HN(SiMe3)2 to Et2O is obtained by hydrolysis of a crystal dissolved in C6D6 with D2O in a NMR tube and integrating the resulting 1H NMR spectrum.
Caution.n‐Butyllithium is pyrophoric in air and reacts rapidly and exothermically with water.
A. BIS{BIS(TRIMETHYLSILYL)AMIDO}IRON(II) DIMER: [Fe{N(SiMe3)2}2]2
The lithium silylamide, LiN(SiMe3)2 (0.80 Et2O) (10.4 g, 0.046 mol), dissolved in diethyl ether (100 mL) is added by cannula to a suspension of FeBr2(THF)2 (8.3 g, 0.023 mol) in diethyl ether at ca. 0 °C, and the suspension is stirred at 0 °C for 12 h.a The diethyl ether is removed under reduced pressure. The green‐yellow residue is extracted with pentane (2 × 50 mL), and the combined red filtrates are taken to dryness under reduced pressure, resulting in a dark red viscous oil. The oil is dissolved in a small amount of pentane (ca. 7–8 mL) and transferred to a distillation apparatus, and the volatile material (including residual THF) is removed at 20 °C under dynamic diffusion‐pump vacuum. After all of the volatile material is removed, the red oil is distilled at ca. 0.01 mmHg over the temperature range of 80–90 °C (bath temperature 115–125 °C) into a receiver flask cooled in an ice bath. The distillate is a green‐yellow mobile liquid that slowly solidifies to a soft green‐yellow solid. The yield is 6.0 g (70%).b
Properties
The [Fe{N(SiMe3)2}2]2 complex is air and moisture sensitive, but it can be stored in a stoppered flask inside of a dry box for extended periods of time. The solid is soluble in hydrocarbons and gives a monomeric molecular ion in the mass spectrum, M+ m/z (calculated intensity, found relative intensity): 376 (100, 100), 377 (36.8, 33.6), 378 (19.8, 17.3), and 379 (4.93, 3.54). The infrared spectrum recorded as a Nujol mull between CsI windows has absorption at 1250 (sh, s), 1240 (s), 1175 (w), 1020 (sh, m), 990 (s), 970 (s), 845 (s), 825 (s), 783 (s), 745 (m), 700 (w), 657 (m), 628 (w), 605(m), and 355 (s) cm−1. The 1H NMR spectrum in C7D8 (30 °C) is a broad resonance at δ = 63. The structure of Fe{N(SiMe3)2} in the gas phase is a linear monomer with two‐coordinate iron atoms.1 The structure in the solid state is dimeric with two silylamide groups bridging the three‐coordinate iron atoms. In toluene solution a monomer–dimer equilibrium exists, for which ΔG = +3 kcal/mol at 300 K.11
References
1. R. A. Andersen, K. Faegri, Jr., J. C. Green, A. Haaland, M. F. Lappert, W.‐P. Leung, and K. Rypdal,
Inorg. Chem.
27
, 1782–1786 (1988).
2. R. R. Fraser, T. S. Mansour, and S. Savard,
J. Org. Chem.
20
, 3232–3234 (1985).
3. P. P. Power,
Chem. Rev.
112
, 3482–3507 (2012).
4. F. Dumestre, B. Chaudret, C. Amien, P. Renard, and P. Fejes,
Science
303
, 821–823 (2004).
5. J. Yang and T. D. Tilley,
Angew. Chem. Int. Ed.
49
, 10186–10188 (2010).
6. Y. Ohki, S. Ohta, and K. Tatsumi,
Inorg. Synth.
35
, 138–140 (2010).
7. S. D. Ittel, A.D. English, C. A. Tolman, and J. P. Jesson,
Inorg. Chim. Acta
33
, 101–106 (1979).
8. B. Horvath, R. Möseler, and E. G. Horvath,
Z. Anorg. Allg. Chem.
450
, 165–177 (1979).
9. D. L. J. Broere, I. Corić, A. Brosnahan, and P. J. Holland,
Inorg. Chem.
56
, 3140–3143 (2017).
10. L. C. H. Maddock, T. Cadenbach, A. R. Kennedy, I. Borilovic, G. Aromi, and E. Hevia,
Inorg. Chem.
54
, 9201–9210 (2015).
11. M. M. Olmstead, P. P. Power, and S. C. Shoner,
Inorg. Chem.
30
, 2547–2551 (1991).
12. C.‐Y. Lin, J. C. Fettinger, and P. P. Power,
Inorg. Chem.
56
, 9892–9902 (2017).
Notes
a
The checkers report that the synthesis may also be performed on the same scale, without the use of THF or FeBr
2
(THF)
2
, by reacting two equivalents of in situ generated LiN(SiMe
3
)
2
in diethyl ether with anhydrous FeCl
2
, freshly generated by dehydrating FeCl
2
⋅4H
2
O by the method of Horvath
8
(cf. also the preparation of THF‐free manganese(II) and cobalt(II) silylamides in this volume). There are three other syntheses of [Fe{N(SiMe
3
)
2
}
2
]
2
from LiN(SiMe
3
)
2
and FeCl
2
6
,
9
or FeBr
2
10
in diethyl ether.
b
The checkers report that the melting point of [Fe{N(SiMe
3
)
2
}
2
]
2
(recrystallized from pentane) is 35–37 °C (cf. 36–38 °C in Ref.
6
). Its UV–Vis spectrum in hexane features absorptions at 380 nm (
ε
= 810 M
−1
cm
−1
) and 626 nm (
ε
= 5 M
−1
cm
−1
). Its Mössbauer spectrum at 80 K features a
δ
= 0.59 mm/s and |Δ
E
Q
| of 1.02 mm/s.
9
Furthermore, it forms the complex Fe{N(SiMe
3
)
2
}
2
(THF) (m.p. 42–45 °C) when recrystallized from THF
11
(the binding constant in hexanes was determined to be 7.8 × 10
3
± 1.4% at 25 °C
12
).
3. BIS{BIS(TRIMETHYLSILYL)AMIDO}COBALT(II) DIMER, [Co{N(SiMe3)2}2]2, AND BIS{BIS(TRIMETHYLSILYL)AMIDO}(TETRAHYDROFURAN)COBALT(II), Co{N(SiMe3)2}2(THF)
Submitted by AIMEE M. BRYAN* and PHILIP P. POWER*
Checked by RICHARD A. ANDERSEN†
*Department of Chemistry, University of California, Davis, CA 95616
†Department of Chemistry, University of California, Berkeley, CA 94720
In the early 1960s, Bürger and Wannagat reported a series of low‐coordinate first‐row transition metal complexes using the silylamido ligand –N(SiMe3)2. The complexes were synthesized via the reaction of NaN(SiMe3)2 with the respective halides in THF solution.1, 2 The resulting hydrocarbon‐soluble amido complexes proved to be useful sources of M2+ and M3+ ions for various inorganic and organometallic reactions.3, 4 However, subsequent work5–7 showed that the original route of Bürger and Wannagat, involving the use of CoI2 and NaN(SiMe3)2 in THF solvent, yielded the complex Co{N(SiMe3)2}2(THF), and not Co{N(SiMe3)2}2 as originally reported. The divalent Co(II) silylamide, Co{N(SiMe3)2}2, which can be most conveniently obtained by carrying out the synthesis in diethyl ether, has been shown to be monomeric in the gas phase,8 to be dimeric in the solid state,9 and to exist in a monomer–dimer equilibrium in hydrocarbon solution.5 Although its crystal structure was reported in 1984,9 the physical, magnetic, and spectroscopic properties of THF‐free [Co{N(SiMe3)2}2]2 were not described in detail until 2013.5 The spectroscopic,5, 6 magnetic,5–7 and structural5–7 characterization of Co{N(SiMe3)2}2(THF) were described in three different publications in 2013–2014.
General Procedures
All reactions are performed with the use of modified Schlenk techniques or in a Vacuum Atmospheres dry box under nitrogen or argon atmosphere. Solvents are dried and collected using a Grubbs‐type solvent purification system (Glass Contour)10 and degassed by using the freeze–pump–thaw method.
Caution.n‐Butyllithium is pyrophoric in air and should be handled under a nitrogen or argon atmosphere. In addition, n‐butyllithium reacts rapidly and exothermically with water. n‐BuH is released during the addition of n‐BuLi to protic reagents. Such reactions should be vented through an oil bubbler.
A. BIS{BIS(TRIMETHYLSILYL)AMIDO}COBALT(II) DIMER: [Co{N(SiMe3)2}2]2
A diethyl ether suspension of LiN(SiMe3)211, 12 is synthesized in situ by adding n‐BuLi (16 mL, 2.5 M solution in hexanes, 0.040 mol) dropwise to HN(SiMe3)2 (8.4 mL, 6.47 g, 0.040 mol) in diethyl ether (40 mL), cooled in an ice bath.a The solution is allowed to come to room temperature and stirring is continued for 12 h. The resulting colorless suspension is added dropwise via cannula over 30 min to a diethyl ether (40 mL) slurry of CoCl2 (2.86 g, 0.022 mol) chilled in an ice bath. An immediate color change of the slurry from blue to dark green is observed. When the addition is complete, the suspension is warmed to ca. 35 °C and stirred for 12 h. The ether is removed under reduced pressure, and the resulting dark green solids are extracted with hexanes (ca. 40 mL), which results in a dark green solution with a gray precipitate. The solution is then filtered through a Celite‐padded filter stick to afford a clear dark green solution. The hexanes are removed under reduced pressure to give a dark green oil. The oil is distilled as a dark green vapor at ca. 100 °C (0.05 Torr) using a short‐path distillation apparatus. Upon cooling, the vapor solidifies to a red/olive mass. The solid is redissolved in hexanes (ca. 30 mL) at ca. 65 °C which affords an olive‐green solution. Cooling slowly to 0 °C gives a precipitate of [Co{N(SiMe3)2}2]2 in the form of red/olive dichroic crystals with a yield of 5.7 g (7.5 mmol, ca. 68%).
Properties
The cobalt(II) bis(silylamide) is both air and moisture sensitive but can be stored inside a nitrogen or argon dry box for several months without noticeable decomposition. If decomposition does occur, redistillation and then recrystallization in hexanes can be used to purify the compound. The compound is soluble in hydrocarbon solvents but exists in a monomer–dimer equilibrium with an association energy (∆Greacn) of −0.30(20) kcal mol−1 at 300 K in benzene solution.5 As a solid, the red/olive dichroic compound is dimeric with bridging silylamide ligands between two three‐coordinate cobalt(II) ions.5, 9 In the gas phase, Co{N(SiMe3)2}2 is monomeric with strictly linear coordination at the cobalt(II) ion.8 M.p. 89–90 °C. UV–Vis/NIR (hexane, 298 K, nm [ε, M−1 cm−1]): 209 [3000], 223 [11 000], 281 [3400], 324 [6500], 604 [140], 668 [200]. IR (Nujol, CsI, cm−1): 3140, 2890, 2710, 2650, 1450, 1368, 1357, 1340, 1290, 1250, 1239, 1150, 1070, 1010, 955, 918, 880, 840, 828, 810, 794, 726, 710, 657, 600, 348, 265. μeff = 4.7(2) μB (C6D6, 298 K, Evans’ method). 1H NMR (295 K, 400 MHz, C6D6): 8.97 (br s, −SiMe3, [Co{N(SiMe3)2}2]2), 0.51 (s, −SiMe3 (terminal), [Co{N(SiMe3)2}2]2), −4.22 (br s, −SiMe3 (bridging), [Co{N(SiMe3)2}2]2) ppm.
B. BIS{BIS(TRIMETHYLSILYL)AMIDO}(TETRAHYDROFURAN)COBALT(II): Co{N(SiMe3)2}2(THF)
Using a preparation similar to that described originally by Bürger and Wannagat, solid LiN(SiMe3)211 (6.68 g, 40 mmol) is added to a rapidly stirred suspension of CoCl2 (2.6 g, 20 mmol) in THF (ca. 40 mL) with cooling in an ice bath. After 1 h, the ice bath is removed and stirring is continued for 12 h to afford a green solution. The THF is pumped off under reduced pressure, and the residue is extracted with pentane (50 mL) and filtered using a Celite‐padded medium frit. The pentane is removed under reduced pressure, and the residual oily green solid is sublimed at ca. 70 °C under reduced pressure (ca. 0.02 Torr) to afford the product Co{N(SiMe3)2}2(THF) as bright green crystals with a yield of 6.23 g, 69%.b Co{N(SiMe3)2}2(THF) can also be obtained by dissolving [Co{N(SiMe3)2}2]2 (2.5 g, 3.29 mmol, see Section 3.A) in THF (ca. 30 mL), which affords a bright green solution. The solution is concentrated under reduced pressure until a green precipitate is formed. Gentle warming to redissolve the solids and cooling for 12 h in a ca. 4 °C refrigerator affords the product [Co{N(SiMe3)2}2(THF)] (2.72 g, ca. 91%).c
Properties
The cobalt(II) bis(silylamide)tetrahydrofuran complex has a bright green color apparently corresponding to the color (giftgrün1) of the product originally described by Bürger and Wannagat as Co{N(SiMe3)2}2. The THF complex is soluble in hydrocarbon solvents. Mp. 71–73 °C. UV–Vis/NIR (hexane, nm [ε, M−1 cm−1]): 680 [90], 1565.10 IR (Nujol, CsI, cm−1): 2980, 2950, 2840, 2720, 1445, 1368, 1252, 1070, 1010, 658, 620, 600, 408, 375, 348, 315, 270. 1H NMR (400 MHz, C6D6, 298 K): 166.9 (br, CH2O), 99.5 (br, CH2O), −17.3 (br s, SiMe3) ppm.
Acknowledgement
The authors thank the U.S. National Science Foundation (Grants CHE‐1263760 and 1565501) for financial support.
References
1. H. Bürger and U. Wannagat,
U. Monatsh. Chem.
94
, 1007–1012 (1964). (Co{N(SiMe
3
)
2
}
2
was originally mis‐characterized as [Co{N(SiMe
3
)
2
}
2
(THF)], see below Refs. 5 and 6).
2. H. Bürger and U. Wannagat,
U. Monatsh. Chem.
95
, 1099–1102 (1964).
3. P. P. Power,
Chemtracts
6
, 181–195 (1994).
4. P. P. Power,
Chem. Rev.
112
, 3482–3507 (2012).
5. A. M. Bryan, G. J. Long, F. Grandjean, and P. P. Power,
Inorg. Chem.
52
, 12152–10160 (2013).
6. B. Cormary, F. Dumestre, N. Liakakos, K. Soulantic, and B. Chaudret,
Dalton Trans.
42
, 12546–12553 (2013).
7. A. Eichhöfer, Y. Lam, V. Mereacre, T. Bodenstein, and F. Weigend,
Inorg. Chem.
53
, 1962–1974 (2014).
8. R. A. Andersen, K. Faegri, Jr., J. C. Green, A. Haaland, M. F. Lappert, W.‐P. Leung, and K. Rypdal,
Inorg. Chem.
27
, 1782–1786 (1988).
9. B. D. Murray and P. P. Power,
Inorg. Chem.
23
, 4584–4588 (1984).
10. A. B. Pangborn, M. A. Giardello, R. H. Grubbs, R. K. Rosen, and F. J. Timmens,
Organometallics
15
, 1518–1520 (1996).
11. U. Wannagat and H. Niederprüm,
Chem. Ber.
94
, 1540–1547 (1961).
12. E. H. Amonoo‐Neizer, R. A. Shaw, D. O. Skovlin, and B. C. Smith,
Inorg. Synth.
8
, 19–22 (1966).
13. C.‐Y. Lin, J. C. Fettinger, and P. P. Power,
Inorg. Chem.
56
, 9892–9902 (2017).
Notes
a
The checker reports that he used a diethyl ether solution of LiN(SiMe
3
)
2
(OEt
2
)
x
(
x
= 0.80) crystallized from diethyl ether at −20 °C.
b
The checker reports that he repeated the Bürger and Wannagat preparation (Ref.
1
) using CoCl
2
and NaN(SiMe
3
)
2
in tetrahydrofuran and upon workup obtained green crystals, Co{N(SiMe
3
)
2
}
2
(THF). A sample of these crystals sublimed at 35–40 °C under a dynamic vacuum (0.01 Torr) and left a dark red‐brown residue that was identified as Co{N(SiMe
3
)
2
}
2
by
1
H NMR spectroscopy.
c
A recent publication
13
has described studies of the binding of THF to Co{N(SiMe
3
)
2
}
2
in hexane. The binding constant was determined to be 1.3 × 10
5
± 1.4%, which is
ca
. 17 times stronger than that of the corresponding iron species (cf. Section 2 above).
4. BIS{BIS(TRIMETHYLSILYL)AMIDO}MANGANESE(II) DIMER, [Mn{N(SiMe3)2}2]2, AND ITS THF COMPLEXES Mn{N(SiMe3)2}2(THF) AND Mn{N(SiMe3)2}2(THF)2
Submitted by MICHELLE FAUST* and PHILIP P. POWER*
Checked by RICHARD A. ANDERSEN†
*Department of Chemistry, University of California, Davis, CA 95616
†Department of Chemistry, University of California, Berkeley, CA 94720
In the early 1960s, Bürger and Wannagat reported a series of low‐coordinate first‐row transition metal complexes of the silylamido ligand –N(SiMe3)2.1, 2 These hydrocarbon‐soluble compounds proved to be useful sources of M2+ ions for various inorganic and organometallic syntheses.3, 4 The divalent Mn(II) silylamide, Mn{N(SiMe3)2}2, was later shown to be monomeric in the gas phase5 and dimeric in the solid state.6, 7 Investigations of the originally reported synthetic route2 revealed that the mono‐THF complex, Mn{N(SiMe3)2}2(THF), is formed first, rather than the THF‐free Mn(II) silylamide,5, 6, 8, 9 and the THF can be removed by heating under argon to form Mn{N(SiMe3)2}2,5 which has a dimeric structure in the crystalline state.7, 10 A subsequent report showed that the bis‐THF complex, Mn{N(SiMe3)2}2(THF)2, can also be formed, and it has been shown to have a four‐coordinate distorted tetrahedral structure in the solid state.10, 11
General Procedures
All reactions are performed with the use of modified Schlenk techniques or in a Vacuum Atmospheres dry box under nitrogen or argon atmosphere. Solvents are dried and collected using a Grubbs‐type solvent purification system12 (Glass Contour) and degassed by using the freeze–pump–thaw method.
A. BIS{BIS(TRIMETHYLSILYL)AMIDO}(TETRAHYDROFURAN)MANGANESE(II), Mn{N(SiMe3)2}2(THF), AND BIS{BIS(TRIMETHYLSILYL)AMIDO}MANGANESE(II) DIMER, [Mn{N(SiMe3)2}2]2
The sodium amide, NaN(SiMe3)2 (5.187 g, 28.3 mmol), synthesized by literature methods,13, 14 is dissolved in tetrahydrofuran (ca. 25 mL). The resulting colorless solution is added dropwise via cannula to a tetrahydrofuran (ca. 20 mL) slurry of freshly dehydrated9 MnCl2 (1.77 g, 14.1 mmol) at room temperature. A gradual color change of the slurry from pink to tan is observed. When the addition is complete, the suspension is heated and maintained at a gentle reflux for 2 h. The tetrahydrofuran is then removed under reduced pressure, and the resulting tan residue is distilled at 110 °C (0.01 Torr) using a short‐path distillation apparatus and a receiving flask cooled with liquid nitrogen. Upon cooling, the vapor solidifies as the salmon‐pink‐colored crystalline species Mn{N(SiMe3)2}2(THF)8, 9 (4.31 g, 9.6 mmol, 68% yield). (Note: Under analogous conditions, the THF‐free Mn{N(SiMe3)2}2 can be synthesized directly by exchanging THF for Et2O as a solvent; however, decomposition during distillation can be extensive and consequently yields are lower.9) The THF‐free silylamide Mn{N(SiMe3)2}2 can be more conveniently obtained by removing the THF from Mn{N(SiMe3)2}2(THF) via heating for 1 h at 120 °C under argon.6, 9 Pink crystals of dimeric [Mn{N(SiMe3)2}2]2 are subsequently grown from pentane (ca. 10 mL in a ca. −18 °C freezer) and isolated in 57% yield (3.02 g, 4.02 mmol).
Properties
The manganese(II) bis(silylamide) mono‐THF complex is a salmon‐pink extremely air‐ and moisture‐sensitive crystalline solid, but it can be stored inside a nitrogen or argon dry box for several months without noticeable decomposition. It is soluble in hydrocarbon solvents and can readily be purified by recrystallization from pentane if contamination does occur.
Mp 35–36 °C. IR (Nujol, CsI, cm−1): 2910, 2730, 2670, 1455, 1375, 1301, 1252, 1242, 1155, 1031, 999, 863, 843, 828, 781, 748, 720, 668, 625, 611, 414, 359, 249. No 1H NMR signals due to the complex could be observed, probably owing to the high magnetic moment.
The manganese(II) bis(silylamide) dimer [Mn{N(SiMe3)2}2]2 is an extremely air‐ and moisture‐sensitive pink crystalline solid but can be stored inside a nitrogen or argon dry box for several months without noticeable decomposition. It is soluble in hydrocarbon solvents and can readily be purified by recrystallization from pentane if contamination does occur. [Mn{N(SiMe3)2}2]2 dissociates to Mn{N(SiMe3)2}2 monomers in the gas phase with strictly linear coordination at the manganese(II) ion.5
In the solid state, [Mn{N(SiMe3)2}2]2 is dimerized via bridging silylamide ligands to afford two three‐coordinate manganese(II) ions.6, 7 Mp 57–58 °C. IR (Nujol, CsI, cm−1): 2990, 2710, 2650, 1445, 1362, 1290, 1245, 1235, 1148, 1062, 988, 919, 850, 835, 818, 775, 740, 710, 655, 621, 600, 348, 268. μeff = 5.7(2) μB (d8‐Tol, 298 K, Evans’ method). Owing to the high magnetic moment, severe broadening of the 1H NMR spectrum occurs and no signal due to the complex could be assigned.
B. BIS{BIS(TRIMETHYLSILYL)AMIDO}BIS(TETRAHYDROFURAN)MANGANESE(II)
Recrystallization of the mono‐THF complex Mn{N(SiMe3)2}2(THF) (ca. 10 mmol, 4.5 g) by dissolving in 15 mL of THF and cooling in a ca. −18 °C freezer resulted in beige crystals of Mn{N(SiMe3)2}2(THF)210, 11 (4.01 g, 76.8%).
Properties
The bis(silylamido) manganese(II)bis‐THF complex is extremely air and moisture sensitive but can be stored inside a nitrogen or argon dry box for several months without noticeable decomposition. The structure of Mn{N(SiMe3)2}2(THF)2 features a substantially distorted tetrahedral coordination at manganese.10, 11 Mp 47–49 °C. IR (Nujol, CsI, cm−1): 2895, 2715, 1455, 1448, 1368, 1245, 1238, 1065, 1023, 990, 856, 833, 821, 772, 741, 714, 691, 661, 618, 603, 411, 352, 240.
C. AN ALTERNATIVE SYNTHESIS OF Mn{N(SiMe3)2}2(THF) AND [Mn{N(SiMe3)2}2]2
Submitted by RICHARD A. ANDERSEN*
Checked by JADE PRATT,† DAVID J. LIPTROT,† and PHILIP P. POWER†
*Department of Chemistry, University of California, Berkeley, CA 94720
†Department of Chemistry, University of California, Davis, CA 95616
General Procedures
The preparation of the starting reagents, MnBr2(THF)2 by Soxhlet extraction of anhydrous MnBr2 with THF, and of Li{N(SiMe3)2}(0.80 Et2O), is outlined in the synthesis of Fe{N(SiMe3)2}2.
Mn{N(SiMe3)2}2(THF)
The lithium silylamide, Li{N(SiMe3)2}(0.80 Et2O) (12.0 g, 0.052 mol) and MnBr2(THF)2 (9.3 g, 0.026 mol), are placed in a 500 mL round‐bottom flask, and THF (150 mL) is added. The solids dissolve forming an orange‐colored solution that is refluxed for 5 h. The solution is allowed to cool to room temperature, the THF is removed under reduced pressure, and the resulting dark colored solid is exposed to a dynamic vacuum for 12 h. Pentane is added (2 × 75 mL), the suspension is allowed to settle, and the filtrates are combined. The volume of the filtrate is concentrated to 20 mL, and the orange‐red solution is transferred to a round‐bottom flask, attached to an all‐glass distillation apparatus that is connected to a diffusion‐pump vacuum line with greased, ground‐glass joints. The volatile material is removed at 20 °C and the orange‐red liquid is distilled from 75 to 80 °C (bath temperature 100–110 °C) into a receiver flask cooled in ice. The yellow‐red liquid slowly solidifies as pink‐reddish needles appear in the liquid on prolonged standing at 20 °C. The yield is 6.0 g, 62%.1
[Mn{N(SiMe3)2}2]2
The THF complex, Mn{N(SiMe3)2}2(THF) (3.0 g, 0.0086 mol), is dissolved in toluene (150 mL) in a 250 mL round‐bottom flask with a greaseless O‐ring joint and stopcock. The flask is attached to a vacuum line connected to an oil‐pump vacuum, and the flask is evacuated. The solution is heated slowly with the stopcock closed; when the toluene vapor reaches the bottom of the greaseless stopcock, the stopcock is opened slowly and toluene is removed over 2 h. The yellowish residue is dissolved in pentane (30 mL) and filtered, and filtrate is concentrated to 15 mL. Cooling to −10 °C affords pink needles from a green mother liquor. The yield is 2.5 g, 77%.
Physical Properties
The melting point for the THF complex was not determined,a but the IR spectrum agrees with that reported by the submitter. The base‐free silylamide melts at 54–55 °C, in agreement with the value reported by the submitter, and sublimes at 55–65 °C in a diffusion‐pump vacuum. Mp = 57–58 °C.
Acknowledgement
The authors thank the U.S. National Science Foundation (Grants CHE‐1263760 and 1565501) for financial support.
References
1. H. Bürger and U. Wannagat,
U. Monatsh. Chem.
94
, 1007–1012 (1963).
2. H. Bürger and U. Wannagat,
U. Monatsh. Chem.
95
, 1099–1102 (1964).
3. P. P. Power,
Chemtracts
6
, 181–195 (1994).
4. P. P. Power,
Chem. Rev.
112
, 3482–3507 (2012).
5. R. A. Andersen, K. Faegri, Jr., J. C. Green, A. Haaland, M. F. Lappert, W.‐P. Leung, and K. Rypdal,
Inorg. Chem.
27
, 1782–1786 (1988).
6. D. C. Bradley, M. B. Hursthouse, K. M. Abdul Malik, and R. Möseler,
Transition Met. Chem.
3
, 253–254 (1978).
7. B. D. Murray and P. P. Power,
Inorg. Chem.
23
, 4584–4588 (1984).
8. P. G. Eller, D. C. Bradley, M. B. Hursthouse, and D. W. Meek,
Coord. Chem. Rev.
24
, 1–95 (1977).
9. B. Horvath, R. Möseler, and E. G. Horvath,
Z. Anorg Allg. Chem.
450
, 165–177 (1979).
10. D. C. Bradley, M. B. Hursthouse, A. A. Ibrahim, K. M. Abdul Malik, M. Motevalli, R. Möseler, H. Powell, J. D. Runnacles, and A. C. Sullivan,
Polyhedron
9
, 2959–2964 (1990).
11. C. R. Hamilton, R. A. Baglia, A. D. Gordon, and M. J. Zdilla,
J. Am. Chem. Soc.
133
, 4208–4211 (2011).
12. A. B. Pangborn, M. A. Giardello, R. H. Grubbs, R. K. Rosen, and F. J. Timmens,
Organometallics
15
, 1518–1520 (1996).
13. U. Wannagat and H. Niederprüm,
Chem. Ber.
94
, 1540–1547 (1961).
14. E. H. Amonoo‐Neizer, R. A. Shaw, D. O. Skovlin, and B. C. Smith,
Inorg. Synth.
8
, 19–22 (1966).
Note
a
Checkers report a Mp = 35–36 °C.
