Metal amides, structure

There have been several reviews on alkali metal amide structural chemistry. Most of these deal with lithium amides but there is also significant coverage of the heavier elements and other topics such as derivatives of primary amides and hydrazides. " Two comprehensive reviews for lithium amides and related salts published in 1991 and 1995 include extensive tables of structural data. There have also been reviews of the of lithium amides as well as of the extensive use of alkah metal... 

The new silazane 5 may be reacted with activated metals, organometallic compounds or simple metal amides, or may first be transformed to its lithium salt and then reacted with metal(II) chlorides [11]. In all these cases, metal derivatives of 5 are obtained with the general formula j [Mc (/BuO)Si 9N(9M, which have no further base coordinated to the metal. So far we have synthesized amides with M = Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Ba, all elements in oxidation state +2. X-ray structure determinations have been performed on the calcium, manganese, iron, zinc, and barium derivatives. 

AIN, GaN, and InN are attractive materials for applications such as blue lasers and field emitters single-source precursors for these of formula [R2MNR 2]2 (R = alkyl, R = alkyl or H) have been reported.236 The reaction of alkylamines with group 13 trialkyl metal compounds affords oligomeric or polymeric ring and cage structures of metal amides and imides (see section on nitrides). 

Scheme 3.6-1. Structural motifs of main group metal amides, phosphanides and arsanides (E = N, P, As).

A. Structural Characterization of Metal Amides in the Solid State... 

Scheme 8), which also control the enolate stereochemistry in amide systems. The influence of metal ion structure on the stereochemical outcome of the aldol process again underscores the importance of metal ligand effects in the enhancement of aldol stereoselection. 

There are a number of amine-catalyzed carbonylation reactions which are catalyzed by cobalt carbonyl and iron carbonyl. It seems to me that these are insertion reactions of metal amides, where carbon monoxide is inserted and then some kind of a reduction or subsequent reaction gives the observed products, urea derivatives or carbamates in alcohols. We do not know the structure of the iron compound it is probably similar to the cobalt species shown. 

TABLE 2. Structurally characterized organomagnesium amides synthesized from the reaction of metal amides with Grignard reagents... 

Molecular structure elucidation, principally by single crystal X-ray diffraction, has become almost routine and is now available for the majority of the metal amides presently discussed. In the 1980 book, however, such data were provided for just 112 compounds, 54 of which were for d- and/-block metals and 41 for the Group 13 metal amides. The contrast with the developing situation is illustrated by reference to Group 1 metal amides from four X-ray data sets in 1980 there were more than 200 by the end of 2007. 

The intervening years have seen huge growth in the number of well-characterized compounds, the vast majority of which are lithium, sodium or potassium salts. Their strucuiral chemistry has proven to be especially rich and the number of structures of alkali metal amides currently available exceeds 200. These involve a wide selection of structural motifs that were mostly unknown in 1980. 

Cationic transition metal amide complexes have been investigated in part because of their potential in catalysis p irticularly for olefin polymerization. Much of this work has concerned polydentate amido, linked cyclopentadienyl-amido or delocalized nitrogen centred bidentate ligands (see later). However, the structures of a small number of cationic complexes containing monodentate amido ligands have been determined. These include... 

R = R = Cy R = 1-adamantyl, R = CfiH 5. Te2-3,5 5 ). The vanadium analogue of the latter [V N(l-Ad)(C6H3Me2-3,5) 3] " 4 has also been characterized. Furthermore, a more efficient route to [Cr N(SiMe3)2 3] and a new crystal structure determination has been described. Three-coordinate metal amides have been treated in a general review that covers three-coordinate transition metal species with hard ligands. The electronic structure and bonding in tricoordinate amido complexes of transition metals have also been detailed... 

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