Dithiocarbamates xanthate complexes

Photoelectron spectroscopy of metal dithiocarbamate, xanthate and dithiophosphate complexes. 

Thus, a series of bis-cyclopentadienetitanium(III) dithiocarbamate and xanthate complexes have been prepared by Coutts et al. (49-51) by reaction of the sodium salts of the ligands with [Cp TiJCl (Cp =7r-cyclo-pentadiene) in air-free water under an inert atmosphere the dithiocarbamate complexes are bright-green, and the xanthates are blue. 

The first xanthates of V(IV), [Cp2V(Rxanth)] (R = Me, Et, Pr , or Bu), isolated as purple solids were prepared by the same method (71). Kwoka et al. (70) were able to obtain an alkylenebis(dithiocarbamate) vanadyl complex, VO[SjjCNH(CH2) NHCS2] for n — 2, but not for... 

Photoelectron spectroscopy of metal dithiocarbamate, xanthate and dithiophosphate complexes. J. O. Hill, R. J. Magee and J. Liesegang, Comments Inorg. Chem., 1985,5,1 (63). 

Later work on the reactions of nickel xanthate complexes, [Ni(S2COR )2], with secondary amines revealed the formation of thiourethanes, R2NC(S)OR, together with nickel bis(dithiocarbamate) complexes (Fig. 26). Both are product of nucleophilic attack of the amine at the -hybridized carbon, the difference between the two pathways being whether the alkoxide or metal-sulfide moieties act as the leaving group (225). 

As discussed earlier (Section IV.I.Lh.ii), the insertion of sulfur into the zinc-sulfur bonds of [Zn(S2CNMe2)2] is proposed to be a key step in the rubber vulcanization process that utilizes this material. However, while the insertion of sulfur into the metal-sulfur bonds of related xanthate complexes is known, to date no such insertion has been noted for dithiocarbamates. However, the insertion of related isoelectronic fragments into the metal-sulfur bond(s) is known. 

More recendy, molecular molybdenum-sulfur complexes and clusters have been used as soluble precursors for M0S2 in the formulation of lubricating oils for a variety of appHcations (70). Presumably, the oil-soluble molybdenum—sulfur-containing precursors decompose under shear, pressure, or temperature stress at the wear surface to give beneficial coatings. In several cases it has been shown that the soluble precursors are trifunctional in that they not only display antifriction properties, but have antiwear and antioxidant characteristics as weU. In most cases, the ligands for the Mo are of the 1,1-dithiolate type, including dithiocarbamates, dithiophosphates, and xanthates (55,71). 

The dithiocarbamates form a series of oxomolybdenum complexes [Mo02(R2dtc)2] and [Mo20s(R2dtc)4]. The xanthates, however, only form [Mo203(Rxanth)4]. The structure of the latter complexes (126) is shown in (X). 

---