Synthesis, characterisation and X-ray crystal structures of diorganotin(IV) complexes with 2-mercaptopyridine derivatives

By reaction of diorganotin(IV) dihalides with esters of 2-mercapto-pyridine-5-carboxylic acid (R = Et, HTNEE; R = iPr, HTNIPE) the complexes R2SnX(L) and R2Sn(L)2 (L = TNEE or TNIPE; R = Me, Et, Bu or Ph) have been prepared and characterised by IR, NMR, and Mossbauer spectroscopies. The structures of Et2SnBr(TNIPE) and Me2SnCl(TNEE) have been determined by an X-ray single crystal diffraction study. Both ligands behave as bidentate chelating groups forming a four-member ring with very similar and small NSnS bite angles. The tin atom is pentacoordinated in a severely distorted trigonal bipyramidal geometry with apical XSnN angles of 151.9(2)° for Et2SnBr(TNIPE) and 154.9(1)° for Me2SnCl(TNEE) and equatorial CSnZ angles of 127.4(6)° and 129.8(2)° respectively. On the basis of 119Sn Mossbauer data, analogous structure are proposed for all the complexes.