Group 5 Element Compounds V, Nb, Ta

Vanadium oxodichloride VOCI2 reacts with sodium thiobenzoate and potassium l,l-bis(thiooxalate) in an aqueous solution to give the corresponding 

Bis(thiocarboxylato) niobium 18Nb(RCOS)2 [207] and bis(r] -cyclopenta-di-enyl)bis(thiobenzoato)niobium 19 [110] have been synthesized by stoichiometric reactions of NbCl2 with sodium thiocarboxylates and of Nb(Cp)2X2 (X=C1, Br, I) with thallium thiobenzoate, respectively. The structure of 19 is considered to be analogous to the tantalum complex 20, in which the thiocar-boxylato ligands are monodentate through the sulfur atom [110]. 

There has been only one example of the synthesis of (r] -cyclopentadienyl)-bis(thiobenzoato)tantalum 20, which was achieved by the reaction of Ta(Cp)2X2 (X=C1, Br, I) with thallium thiobenzoate [110]. The molecular structure of 20 is a normal, bent sandwich geometry where the two thiocarboxylato ligands are planar and are monodentate through the sulfur atom (for bond distances, see Table 2) [110]. 

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