Adducts of triphenyllead isothiocyanate and selenocyanate with some O- and N-donor ligands

Abstract

The preparation and properties of triphenyllead selenocyanate have been reinvestigated. Infrared spectra show that the solid is polymeric with strong Pb—Se and weak Pb—N bonds; in benzene or CH2Cl2 solutions ν(CN) values are consistent with the Ph3PbSeCN bonding mode. The first 1:1 adducts of triphenyllead selenocyanate with hexamethylphosphoramide (HMPA), pyridine-N-oxide (pyO), 4-picoline-N-oxide (4-picO), and triphenylphosphine oxide (TPPO) have been prepared; infrared data show that Ph3PbSeCN•L (L = pyO, 4-picO, TPPO) are selenocyanates, but the HMPA adduct is an isoselenocyanate. The adducts dissociate in benzene and ν(CN) frequencies show that both N-bonded and Se-bonded adduct isomers are present. In contrast, the adducts Ph3PbNCS•L (L = HMPA, pyO, 4-picO, TPPO) are N-bonded in the solid state and in benzene solution where they are undissociated. Amine adducts, Ph3PbNCS•L (L = pyridine, β-picoline, γ-picoline, pyrrolidine (pyrrol), piperidine (pipy), cyclohexylamine (CyNH2)) and Ph3PbNCS•2L (L = morpholine (morph)), as well as Ph3PbNCSe•pipy and 2 Ph3PbNCSe•3L (L = pyrrol or morph) have been prepared, but these are less stable than adducts with O-donor ligands. Infrared data suggest that amine adducts of Ph3PbNCS have N-bonded and/or ionic thiocyanate groups while all Ph3PbSeCN–amine adducts contain the selenocyanate ion.