Organometallic complexes with biological molecules. I. 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. Fanally, the solution‐phase spectral features of (R2SnCl)2−H2PPIX are in agreement with the monomeric character of the protoporphyrin IX, under the experimental conditions used.