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(C OOR)CH (HTNME, R = methyl; HTNEE, R = ethyl; HTNIPE, R = isopropyl) th e 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 Mos sbauer spectroscopies. Moreover, the Ph(2)SnCl(2)/2-mercaptopyridine ( HMP) system has been found to yield either the Ph(2)SnCl(2)(HMP)(2) ad duct or the Ph(2)SnCl(MP) complex. The structures of Ph(2)SnCl(TNEE) a nd Ph(2)SnCl(MP) have been determined by X-ray single-crystal diffract ion studies. The two structures are similar. Both ligands behave as bi dentate chelating groups forming a four-membered ring with an identica l small N-Sn-S bite angle of 63.7 degrees. The tin atom is pentacoordi nated, presenting a severely distorted trigonal bipyramidal geometry w ith 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)d egrees and 125.0(3)degrees respectively. On the basis of Sn-119 Mossba uer 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 co ordination 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.