Adducts of diphenyllead diselenocyanate with some O- and N-donor ligands

Abstract

The preparation and properties of Ph2Pb(SeCN)2 have been reinvestigated. Infrared spectra show that the solid is polymeric with stronger Pb—Se and weaker Pb—N bonds. In N,N-dimethylformamide (DMF) solution v(CN) values are consistent with complete ionization to NCSe−, but coordinated N- and Se-bound selenocyanate species are observed when DMF/CH2CI2 mixtures are used as solvents. The first 1:2 adducts of Ph2Pb(SeCN)2 with hexamethylphosphoramide (HMPA), triphenylphosphine oxide (Ph3PO), pyridine-N-oxide (pyO), 2,4,6-collidine-N-oxide (collO), and dimethyl sulphoxide (DMSO) have been prepared, while with 4-picoline-N-oxide (4-picO) a 1:4 adduct is obtained. Infrared data show Ph2Pb(SeCN)2•2L (L = HMPA, Ph3PO, collO) are in fact isoselenocyanates, but the pyO and DMSO adducts are selenocyanates. Amine adducts Ph2Pb(SeCN)2•2L (L = morpholine (morph), quinoline (quin), piperidine (pipy)) and Ph2Pb(SeCN)2•3LL (LL = α.α′-dipyridyl (dipy), 1,10-phenanthroline (phen)) have been prepared. Infrared data suggest that amine adducts most probably have N-bonded selenocyanate groups, in some cases with ionic selenocyanate also present. The adduct with 4-picO also contains ionic selenocyanate.