ORGANOMETALLIC COMPLEXES WITH BIOLOGICAL MOLECULES .1. DIORGANOTIN(IV)CHLORO PROTOPORPHYRIN-IX COMPLEXES - SOLID-STATE AND SOLUTION-PHASE CHARACTERIZATION

Protoporphyrin IX (H4PPIX) complexes of diorganotin(IV)chloro moieties with formula (R2SnCl)2H2PPIX (R = Me, Bu and Ph) have been obtained and their solid-state and solution-phase configurations have been studied through spectroscopic investigations. Coordination of the side-chain carboxylates of H4PPIX to R2Sn(IV)Cl moieties, with bridging carboxylate (COO-) has been inferred by comparison of the free and coordinated H4PPIX IR spectra, while the occurrence of a five-coordinated tin(IV) atom in a cis-R2 trigonal bipyramidal structure has been deduced, for all of the synthesized complexes, by rationalization of the nuclear quadrupole splitting parameters, according to the point-charge model formalism. Finally, the solution-phase spectral features of (R2SnCl)2H2PPIX are in agreement with the monomeric character of the protoporphyrin IX, under the experimental conditions used.