New insights on the Lewis acidity of diorganolead(IV) compounds: Diphenyllead(IV) complexes with N,O,S-chelating ligands

Abstract

The reactions of PbPh 2(OAc) 2 with alkylglyoxylate thiosemicarbazones (HRGTSC, R = Et, Bu) afforded complexes of the type [PbPh 2(GTSC)] · H 2O, [PbPh 2(RGTSC) 2] and [PbPh 2Cl(BuGTSC)]. The structures of HRGTSC (R = Me, Et, Bu), [PbPh 2(OAc)(RGTSC)](R = Me, Et, Bu), [PbPh 2Cl(BuGTSC)] and [PbPh 2(GTSC)] · H 2O have been studied by X-ray diffraction. [PbPh 2(OAc)(RGTSC)] and [PbPh 2(GTSC)] · H 2O have [PbC 2NO 3S] kernels and the coordination sphere of the metal is pentagonal bipyramidal. [PbPh 2Cl(BuGTSC)] has a [PbC 2NOSCl] kernel and the coordination geometry around lead is pentagonal bipyramidal with one vacant site. Analysis of the bond distances in [PbPh 2(GTSC)] · H 2O suggests a significant affinity between diphenyllead(IV) and carboxylate donor groups, supporting a borderline acidic character for this organometallic cation. 1H and 13C NMR spectra in DMSO- d 6 suggest the partial dissociation of the acetate in [PbPh 2(OAc)(RGTSC)] solutions and indicate some differences in the coordination mode of the two RGTSC − ligands in [PbPh 2(RGTSC) 2] complexes.