Organotin isothiocyanate complexes: the interaction of alkyltin isothiocyanates with ligands containing oxygen or nitrogen as the donor atom

Abstract

Methyltin tri-isothiocyanate MeSn(NCS)3 and the dialkyltin di-isothiocyanates R2Sn(NCS)2(R = Me, Et, Bu, and octyl) form six-co-ordinate adducts with some or all of the ligands pyridine, 1,10-phenanthroline, 2,2′-bipyridyl, pyridine 1-oxide, quinoline 1-oxide, triphenylphosphine oxide and triphenylarsine oxide. The stability of the complexes diminishes as the size of the alkyl group R is increased. The methyl groups occupy trans-positions in the octahedral Me2Sn(NCS)2 complexes. Trimethyltin isothiocyanate Me3Sn(NCS) forms 1 : 1 adducts with monodentate ligands, the five-co-ordinate compounds having trigonal-bipyramidal structures with the methyl groups approximately in a plane around the tin atom. 1,10-Phenanthroline yields a six-co-ordinate complex Me3Sn(NCS),phen, but 2,2′-bipyridyl behaves as a nonchelate ligand forming complexes Me3SnNCS, bipy and 2Me2SnNCS,bipy for which five-co-ordinate structures are proposed. Comparison with Me3SnCl,bipy suggests that in this latter compound the bipyridyl is chelated and the tin atom six-co-ordinate.