Reactions of diorganotin(IV) oxides with isatin 3-and 2-thiosemicarbazonesand with isatin 2,3-bis(thiosemicarbazone): influence of diphenyldithiophosphinic acid (isatin=1H-indole-2,3-dione)

Reaction between SnMe2O and isatin 3-thiosemicarbazone (HLI) in the presenc e of diphenyldithiophosphinic acid (HS2PPh2) afforded [SnMe2(S2PPh2)(2)] an d [SnMe2LI{O(S)PPh2}]. EtOH, which were studied by X-ray diffraction and IR spectroscopy in the solid state and by multinuclear (H-1, C-13, P-31 and S n-119) NMR spectroscopy in CDCl3 or dmso-d(6) solution (isatin=1H-indole-2, 3-dione). In the bis(dithiophosphinate) derivative the tin atom is bound to two strongly anisobidentate ligands both in the solid state and in solutio n in chloroform. In the mixed-ligand complex the monothiophosphinate ligand is O-co-ordinated and the thiosemicarbazone (TSC) is bound primarily throu gh its sulfur atom and the nitrogen atom of the azomethine group, although there is an additional weak bond with the remaining isatin oxygen atom [O(1 )]. The NMR spectrum in dmso-d(6) suggests weakening of the Sn-S bond and r einforcement of the Sn-O(1) bond. For comparison, the structure of HLI was also studied by X-ray diffraction. Reaction of SnMe2O with isatin 2,3-bis(t hiosemicarbazone) (H2LL) afforded [SnMe2(LL)]. X-Ray diffraction shows that one TSC chain is bound to the metal through the sulfur atom and the azomet hine nitrogen atom, forming a five-membered metallacycle. The other chain c o-ordinates through the nitrogen of the hydrazine group following its depro tonation. The co-ordination sphere changes in dmso-d(6) solution, in which a molecule of solvent probably occupies a co-ordination position to make th e co-ordination number of the metal center up to six. The spectra of the ot her [SnR2(LL)] complexes prepared (R=Et or Bu) suggest that both have struc tures similar to that of the methyl derivative. Reaction of SnMe2O with isa tin 2-thiosemicarbazone (H2LII) gave [SnMe2LII], the NMR spectra of which i ndicate a five-co-ordinated tin atom and an O,N,S-tridentate TSC ligand.