N-heterocyclic dithiocarbamate platinum(II) complexes: Unexpected transformation of dithiocarbamate to oxodithiocarbonate in phosphinoplatinum complexes in solution

[PtCl2(dppe)] (dppe = 1,2-bis(diphenylphosphino)ethane) reacts with pyrazol-1-yl- (L1), 3,5-dimethylpyrazol-1-yl- (L2), and indazol-1-yl- (L3) dithiocarbamate to form [Pt(L1)2(dppe)] (1), [Pt(L2)2(dppe)] (2) and [Pt(L3)2(dppe)] (3). These complexes readily transform into [Pt(S2CO)(dppe)] (4) in chloroform and dichloromethane at room temperature. Stability of the bis(dithiocarbamate)platinum complex from L2, [Pt(L2)2] (5) suggests that the transformation of 1–3 to 4 is facilitated by the phosphine ancillary ligand.