Synthesis and characterization of organotin complexes with 2-mercaptopyridine derivatives

By reaction of diphenyltin(IV) chloride and triphenyltin(IV) hydroxide with esters of the 2-mercaptopyridine-5-carboxylic acid NH(CS)CHCHC(COOR)CH (HTNME, R = methyl; HTNEE, R = ethyl; HTNIPE, R = isopropyl) the complexes Ph(3)Sn(L), Ph(2)SnCl(L) (L = TNME, TNEE and TNIPE) and Ph(2)Sn(TNEE)(2) have been prepared and characterized by IR, NMR and Mossbauer spectroscopies. Moreover, the Ph(2)SnCl(2)/2-mercaptopyridine (HMP) system has been found to yield either the Ph(2)SnCl(2)(HMP)(2) adduct or the Ph(2)SnCl(MP) complex. The structures of Ph(2)SnCl(TNEE) and Ph(2)SnCl(MP) have been determined by X-ray single-crystal diffraction studies. The two structures are similar. Both ligands behave as bidentate chelating groups forming a four-membered ring with an identical small N-Sn-S bite angle of 63.7 degrees. The tin atom is pentacoordinated, presenting a severely distorted trigonal bipyramidal geometry with apical Cl-Sn-N angles of 155.0(2)degrees [Ph(2)SnCl(TNEE)] and 155.7(7)degrees [Ph(2)SnCl(MP)] and equatorial C-Sn-C angles of 114.9(2)degrees and 125.0(3)degrees respectively. On the basis of Sn-119 Mossbauer data, all the complexes should present analogous structures except Ph(2)Sn(TNEE)(2) and Ph(2)SnCl(2)(HMP)(2), for which an octahedral coordination geometry with a trans arrangement of the phenyl groups can be proposed. The effect of dimethyl sulphoxide on Ph(2)SnCl(L) and Ph(2)SnCl(2)(HMP)(2) is also discussed.