Amido/thiolate complexes

For the preparation of mixed amido/thiolate complexes the reaction of [(Me3Si)2N]2-LnCl(THF)x (Ln-Y,Eu,Gd) with lithium tert-buthylthiolate has been employed [7]. 

Rheniumi ) 0x0 bioconjugates have been prepared with chelating NjS donor ligands such as amino/amido/thiolates, mixed-ligand complexes of tridentate ligands with... 

In addition to complexes with ON donor sets, complexes with bidentate N-donor atoms and other donors have been described. For example, after several solution studies the crystal structure of the bis(L-cysteine methyl ester)oxovanadium(IV) complex showed that the vanadium is coordinated by the amido nitrogens and thiolate sulfurs (128).561 The complexes and reactivity of a series of pyridine-2-thiolate complexes of V(IV, III, and II) have been characterized (129-131).651 The mass spectrometric fragmentation patterns of two of these complexes were investigated and show the formation of six 1 1 complexes and one 1 2 complex in the gas phase.651... 

P-Hydrogen eliminations and p-aryl eliminations from alkoxo and amido complexes are also known. Such eliminations have been shown to occur by migratory de-insertion pathways, as well as alternative p-hydride abstraction mechanisms. P-Hydrogen eliminations from metal-silyl complexes are rare because the silicon-carbon double bond in the product is weak. For similar reasons, p-hydrogen eliminations from metal-thiolate complexes are rare. 

Munro-Leighton C, Delp SA, Alsop NM, Blue ED, Gunnoe TB. A ti-Markovnikov hydroamination and hydrothiolation of electron-deficient vinylarenes catalyzed by well-defined monomeric copper(I) amido and thiolate complexes. Chem. Commun. 2008 111-113. 

These 0x0 Re complexes can furnish various derivatives, for example, with N-, 0-, S-, or C- ligands, that is, Re oxo-amido, -imido, -alkoxide, -phenoxide, -diolate, -thiolate, -alkyl, or - aryl complexes, on reactions of (13) or (14) with amines, alcohols, phenoxides, diols, thiols, organozinc, or Grignard reagents, respectively. 

A Ni amido complex supported by a thioether/thiolate chelating ligand that promotes the desoxygenation of CO, CO2, and SO2 has been described, (29). The product, NCO, and mechanism of CO2 reduction involving CO2 insertion into the Ni—bond, bear no resemblance to the enzymatic process. 

A few final comments should be made on the insertions of substrates containing C-C multiple bonds into the bonds between a transition metal and an electronegative heteroatom. First, insertions of olefins into related thiolate and phosphide complexes are as rare as insertions into alkoxo and amido complexes. Reactions of acrylonitrile into the metal-phosphorus bonds of palladium- and platinum-phosphido complexes to give products from formal insertions have been observed, and one example is showm in Equation 9.90. However, these reactions are more likely to occur by direct attack of the phosphorus on the electrophilic carbon of acrylonitrile than by migratory insertion. Second, the insertions of alkynes into metal-oxygen or metal-nitrogen covalent bonds are rare, even though the C-C ir-bond in an alkyne is weaker than the ir-bond in an alkene. 

Different sets of experiments have made it possible to compare the rates for reductive elimination from arylpaUadium amido, alkoxy and thiolato complexes bearing similar substituents on the heteroatom, following the trend C-S > C-N > C-O [397]. Although the thiolate hgand is less basic than an amido ligand, it is much more polarizable. The rate of reductive ehmination is controlled by the polarizability of the heteroatom, which is of the same importance as the overall electron-donating ability. 

The first report outlining the synthesis of a homoleptic product was the synthesis by Bochkarev of the divalent compound (Yb(EBu)2 E = S, Se), prepared by a proton-transfer reaction of an amido precursor with HEBu. This was followed by the metatiietical synthesis of Ln(SR)6 and compounds of the heavier chalcogenolates (Ln(EC6H3R3)2 (E = Se, Te R = Me). " The structure of the thiolate compound was described, but stmctural characterization of selenolate and tellurolate compounds did not appear until later, when the E-Si(SiMes)3 ligand was introduced to the Ln field, and new synthetic approaches to complexes of the EPh ligand were developed. 

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