Thiolates mononuclear complexes

Muller, A. and Henkel, G. (1995) [Ni2(SC4H9)g] , a novel binuclear nickel-thiolate complex with NiS4 tetrahedra sharing edges and [Ni(SC( H4SiMe3)4] , a structurally related mononuclear complex ion. Z. Naturforsch., B50, 1464-8. 

When simple nickel(II) salts are treated with thiols, in most cases stable thiolate-bridged polymers are formed. In a number of cases, treating these polymers with either tertiary phosphines or isocyanides gave mononuclear mixed-ligand complexes (equation 204).1951 These mononuclear complexes, due to the presence of terminal thiolates which possess lone pairs, can further react with nickel(II) and give trinuclear complexes (equation 205).1952... 

In addition to rapid exchange of thiolate ligands with R SH and for R S , the mononuclear complexes [Fe(NO)2(SR)2] also undergo (23) rapid exchange of the nitrosyl ligands in the presence of isotopically labeled nitrite a W-shaped N203 intermediate was proposed (23) [Eq. (22)]. 

Condensation of ketones or aldehydes with the methyl ester of dithiocarbazic acid produces hgands with S,N,0 or S,N donor sets. An example is (142), which acts as both a didentate and a tridentate to ReO. Nickel(II)-templated reactions of pentanedione or salicylaldehyde with aminoethanethiol produce N,0,S ligands such as (143) and (144) these form simple mononuclear complexes or else dinuclear species with thiolate bridging two Ni centers. Mixed donor Schiff-base hgands including other heteroatoms such as P (145) and Te (146) have appeared. 

Ooi and co-workers adopted an elegant synthetic approach to the mixed-metal complexes of 4-methylpyridine-2-thiolate (4-mpyt). This approach includes the initial preparation of mononuclear complexes [M(4-mpytH)4]Cl2 (M = Pt, Pd), in which all four 4-mpytH ligands coordinate to with sulfur-donor atoms (84,102). The structure of the mononuclear Pd(II) complex with nonsubstituted pyridine-2-thiolate, [Pd(pytH)4]Cl2, is shown in Fig. 16 (84). These mononuclear complexes can be further reacted with the second metal ion to give mixed-metal dinuclear complexes. 

Under certain conditions, the preference of Hg(II) for a CN = 2 with thiolate as a ligand can be overcome, and a few simple mononuclear complexes of the formulas [Hg(SR)3j and [Hg(SR)4] have been structurally characterized. Unfortunately, only Bowmaker et al. (23) and Liesk et al. (119) have reported vibrational data. As was found with chloride compounds, the structure, and hence the vibrational spectra, of anionic Hg(II) thiolates are very cation dependent. Moreover, these studies considered only phenyl, methyl, and t-Bu derivatives, which are more dissimilar than similar. Nonetheless, the data are consistent and effectively distinguish bonding interactions (primary CN = 3,4) from secondary interactions (primary CN = 2). Based on correlation of the structurally characterized complexes and vibrational data it is not possible at this time to distinguish between three- and four-coordinate complexes on vibrational data alone. 

It has been mentionned above that the binuclear thiolate complex undergoes two successive reversible oxidations. The first oxidation wave takes place at a potential more positive than the oxidation of the mononuclear complex, as generally observed in related systems. The corresponding radical is stable on the time scale of cyclic voltammetry. It could also be observed by ESR at temperatures lower than -30 C. The second oxidation leads to a cationic compound RS[Cr(CO)5]2 which can be described as an organometallic sulfonium cation isoelectronic with the previously described phosphinidene species RP[Cr(CO)5]2-... 

Chelation of ixo-maleonitriledithiolate (imdt) has been structurally characterized in the octahedral cobalt(III) complex trmw-[Co(imdt)2(P(ra-Bu)3)2], formed via reaction of cobalt(II) ion with K2(imdt) in the presence of the phosphine.1037 Simple chelating thiolates such as SCH2CH2S not only form mononuclear compounds, but participate in bridging in clusters such as [Co3(SCH2CH2S)3(PEt3)3]3+ (243).1038... 

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