TRIPHENYLLEAD ISOCYANATE AND ADDUCTS WITH SOME O- AND N-DONOR LIGANDS: SYNTHESES AND SPECTROSCOPIC STUDIES

Article abstract of DOI:10.1016/S0022-328X(00)82936-8

The preparation and properties of triphenyllead isocyanate have been reinvestigated and its synthesis (68percent yield) by the reaction of triphenyllead acetate with potassium cyanate in boiling methanol is reported.The first 1/1 adducts of triphenyllead isocyanate with the ligands: hexamethylphosphoramide (HMPA), dimethyl sulphoxide (DMSO), N,N-dimethylacetamide (DMA), N,N-dimethylformamide (DMF), triphenylphosphine oxide (TPPO), trimethyl phosphate (TMP), and pyridine (py), have been prepared and characterised by infrared, Raman, and 31P NMR spectroscopy.The adducts are white solids with melting points in the range 78-143 deg C; the TMP and py adducts dissociate slowly on standing at room temperature and only the HMPA and TPPO adducts could be recrystallized from benzene.The infrared and Raman spectra of solid Ph3PbNCO are consistent with a polymeric structure, with Ph3Pb groups joined by cyanate bridges so that each lead has a distorted trigonal-bipyramidal coordination.Adduct formation by Ph3PbNCO probably involves the breaking of cyanate bridges at the weaker Pb-O bonds followed by formation of lead-ligand bonds so that each lead retains five coordination in a molecular structure.