The X-ray crystal structure of dichloro-S,S′-bis(o-methylcysteinato)tin(IV): the first determination of an inorganic tin—amino acid derivative

Abstract

The crystal structure of dichloro-S,S′bis(O-methylcysteinato)tin(IV), Cl 2Sn{SCH 2CH(NH 2)-CoOMe} 2, has been solved by a three-dimensional Patterson synthesis: the crystals are orthorhombic, space group P2 12 12 1, with cell parameters a = 16.621(9), b = 9.843(5), c = 10.323(5) Å, Z = 4, refined to R = 0.0356 for 1715 observable reflections. The tin is coordinated to two cis-nitrogen and two trans- sulphur atoms from the O-methylcysteinato ligands, and to two cis- chlorine atoms, in an approximately octahedral arrangement. The bond distances in the tin coordination sphere are: SnCl 2.445 Å, SnS 2.434 Å and 2.446 Å, and SnN 2.264 Å and 2.309 Å. This structure is compared with those of other octahedral cis-Cl 2Sn(L 2) 2 complexes and the results of anti-tumour tests on these derivatives are reported. The lack of anti-tumour activity exhibited by the title compound may be associated with the large (99.4°) cisClSnCl bond angle.