DIORGANOTIN(IV) MERCAPTOCARBOXYLATO COMPLEXES

The structure and bonding in Alk(2)Sn(IV)- and Ph(2)Sn(IV)-mercaptoace tate, -3-mercaptopropionate, -mercaptosalicylate and -mercaptosuccinat e complexes have been investigated by vibrational and Sn-119 Mossbauer spectroscopies. The IR data indicate the occurrence ol: bidentate car boxylato groups, of non linear CSnC bonds [in the Me(2)Sn(IV) derivati ves], and of Sn-S bonds. The point-charge model rationalization of the Mossbauer nuclear quadrupole splittings, Delta E, in conjunction with the estimate of the sign of Delta E and of the value of the asymmetry parameter eta obtained from the Mossbauer-Zeeman spectra of two repre sentative complexes, indicates the general occurrence of trigonal bipy ramidal environments of the tin atoms, as well as a polynuclear nature of the solids due to axially bridging carboxylato groups. The correla tion of the Mossbauer parameters isomer shift, delta, with partial ato mic charges on the tin atoms, Q(Sn), confirms the occurrence of trigon al bipyramidal structures.