Infrared Spectra of Triphenyltin lsoselenocyanate and Its Adducts with O- and N-Donor Ligands

Department of Chemistry, McGill University, Montreal, Quebec, Canada, H3A 2K6 The preparation and properties of triphenyltin isoselenocyanate have been rein­vestigated. Infrared spectra show that the solid is polymeric with strong Sn—N and weak Sn— Se bonds ; in benzene or CH2CI2 solutions, CN values are consistent with the presence of both Ph3SnNCSe and Ph3SnSeCN. In a variety of donor solvents (tetrahydrofuran, acetone, acetonitrile, pyridine (py), and N,N'-dimethylformamide (DMF)), increasing donor power causes adduct formation and then ionisation. Infrared data indicate that 1 :1 adducts of triphenyltin isoselenocyanate with hexamethylphos­phorariide (HMPA), triphenylphosphine oxide (TPPO), 2,4,6-collidine-N-oxide (collO), dimethyl sulphoxide (DMSO), pyridine-N-oxide (pyO), 4-picoline-N-oxide (4-picO), β-Picoline (β-pic), and \(\gamma\)-picoline (\(\gamma\)-pic), as well as Ph3SnNCSe.L (L=py or DMF), are isoselenocyanates. For equilibria in CH2CI2 solution at 22°, K=1.2±0.3 for Ph3SnNCSe\(\rightleftharpoons\)Ph3SoSeCN, while dissociation constants are estimated to be 3 x 10-3, 1.6 x 10-3, 8 x 10-4 and 1.7 x 10-3 M for Ph3SnNCSe.L\(\rightleftharpoons\)Ph3SnNCSe+L, where L=DMF, py, \(\gamma\)-plc, and β-pic, respectively