Sulfido ligand, terminal

Interesting new sulfido complexes of tin have been prepared by the reaction of styrene sulfide with the N-alkylated tin(II) amidinate complexes Sn[RC(NCy)2]2 (Cy = cyclohexyl R = Me, Bu ). The products exhibit two very different bonding modes for the sulfido ligands in one case, S = Sn[RC(NCy)2]2/ a terminal Sn = S moiety was found while in the other case the bridging... 

The coordination chemistry of the sulfido ligand is very varied. Scheme 4 illustrates the modes of coordination of to transition metal ions. The monosulfido ligand can act as a two-electron, terminal or /u-2-bridging donor, or up to a six-electron donor if it binds as /u.4-bridging or interstitial donor. It is, therefore, not surprising that a wide variety of binuclear and polynuclear sulfido clusters complexes can be prepared. 

The deprotonation reaction of Cp2Ti(SH)2 with NaH in THF proceeds unexpectedly with the elimination of GpH to give the anionic sulfide-bridged titanium(iv) dimer, Na2[CpTi(/x-S)(S)]2. The molecular structure of this compound has been determined by X-ray diffraction and shows a terminal sulfido ligand with a short Ti-S bond distance of ca. 2.2 A, indicating nearly double bond character (Scheme 417). It adopts a yy/z-Ti=S configuration and is stabilized by interactions with THF-solvated sodium cations.1009... 

These anionic complexes are important for giving, by oxidation of terminal disulfido groups, very reactive, trinuclear cationic species In molybdothio-compounds involving Mo- 7 -S(2 or 4) moieties, various specific functional groups were clearly identified and engaged in nucleophilic attack on di-carbomethoxyacetylene, leading to the conversion of (S ) sulfido ligands into dithiolene. ... 

The occurrence of Mo or W in Nature is, with the exeeption of nitrogenase, always accompanied by a unique pyranopterin dithiolene chelating ligand typically referred to as molybdopterin and this is always coordinated to the metal at the active site. The combination of Mo (or W) with either one or two bidentate molybdopterin ligands in addition to combinations of terminal oxido or sulfido ligands and amino acid side chains leads to an orderly classification of this enzyme family into three sub-groupsthe xanthine oxidase, sulfite oxidase and DMSO reductase families (Scheme 5.1). The eponymous enzyme in each case is historically the first one isolated and studied within its family. 

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