119 Sn Mössbauer studies of bis[cysteinato(1 − )‐ S ]‐ and bis[penicillaminato(1 − )‐ S ]‐diorganotin(IV) species in the crystalline state and in frozen aqueous solution

The bonding and the configuration of the tin environment in the title compounds {R 2 Sn[SCH 2 CH(NH 3 + )COO − ] 2 and R 2 Sn[SC(CH 3 ) 2 CH(NH 3 + )COO − ] 2 , indicated in the following as R 2 Sn(cysH) 2 and R 2 Sn(penH) 2 respectively} has been investigated through the determination of the Mössbauer‐Zeeman spectra of Ph 2 Sn(cysH) 2 and Ph 2 Sn(penH) 2 in the solid state, and through conventional Mössbauer spectroscopy of Me 2 Sn(penH) 2 in the solid state as well as of Me 2 Sn(cysH) 2 and Me 2 Sn(penH) 2 in aqueous solution (frozen). The treatment of the data by the pointcharge model approach suggested the general occurrence of a tetrahedral C 2 SnS 2 core. In aqueous Hepes buffer, a tertiary amino nitrogen atom has been observed to coordinate tin in Me 2 Sn(cysH) 2 and Me 2 Sn(penH) 2 , with formation of trigonal bipyramidal tin environments. The latter solutions undergo slow decomposition reactions at room temperature. From (Me 2 SnS) 3 occurs, as well as formation of soluble complex species in the presence of glycylglycine; Me 2 Sn(penH) 2 appears to undergo a slow desulfuration reaction.