Titanium, dithiocarbamate complexes

Coutts and Wailes (52, 53) synthesized a series of 5-coordinate, mono-cyclopentadiene dithiocarbamate complexes of titanium(III) and tita-nium(IV), [CpTi(S2CNR2)2] (R =Me, Et, or Pr), prepared by ligand-exchange reactions between CpTiCl2 and Na(S2CNR2). Infrared spectra and molecular-weight data suggested (52) structure (VI). CpTiXj... 

An earlier report on paramagnetic titanium(III) complexes, [Cp2Ti(S2-CNR2)], appears to be erroneous (609). More recently, the synthesis of the yellow-green, air-sensitive, titanium(III) complexes, [Ti(S2CNR2>3] (R = Me, Et, Pr, Bu), has been claimed. They supposedly result from the addition of dithiocarbamate salts to TiCla in ethanol and have been characterized by IR spectral data and magnetic measurements, the latter appearing to show that the state is retained (610, 611). There appears to have been no further reports of these complexes and their true identity may require further consideration. 

Toxicity studies of these same tetrakis(dithiocarbamate) complexes toward houseflies and cockroaches have been carried out, showing that the titanium complexes are slightly more toxic than the analogous sodium salts (616). 

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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