Hafnium, dithiocarbamate complexes

Two recent papers on [(jj-C5H5)M(S2CNMe2)3] (M = Zr or Hf) and [(rj-C5H5)2ZrCl(S2CNR2)] (R = Me or Et) are mentioned in passing to provide an entry into the current literature on organo-zirconium and -hafnium dithiocarbamate complexes. 

Group 4 (IV B) dithiocarbamate chemistry is constrained to the 4-4 oxidation state. The first reported example was the eight-coordinate tetrakis(dithiocarba-mate) titanium complex, [Ti(S2CNBz2)4], prepared by Dermer and Femelius in 1934 (608), while the heavier zirconium and hafnium analogues were first prepared by Bradley and Gitlitz (193) from the reaction of metal amides, [M(NR2)4] (M = Ti, Zr, Hf), with carbon disulfide. 

Titanium and hafnium complexes [CpMCl2(S2CNR2)] and [CpMCl(S2-CNR2)2l, in which the dithiocarbamate derives from substituted thiadiazoles (Fig. 4) have also been prepared (52, 631). For the titanium complexes, on the basis of IR data in which two v(C—S) bands are observed, it is postulated that each dithiocarbamate and the nitrogen of the thiadiazole ring is metal bound to produce six-membered chelate rings, however, this has not been confirmed crystallographically (52). 

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