Porphyrin complexes of platinum(II), platinum(III), and platinum(IV): Synthesis and properties

Complexing mesotetraphenylporphine H2TPP with K-2[PtCl6] in boiling pyridin e or with K-2[PtCl4] in boiling benzonitrile produces stable platinum compl exes of composition (Cl)(2)(PtTPP)-T-IV or (PtTPP)-T-III. Reacting mesoporp hyrin dimethyl ether H2MP with K-2[PtCl6] in boiling pyridine yields (Cl)(P tMP)-M-III, a complex in which platinum has an unusual oxidation number. Th e complexes are identified using UV and IR spectroscopy, by atomic adsorpti on spectrometry, and by quantitative analysis. The species of the complexes existing in mixed H2SO4-containing proton-donating solvents are discovered . The kinetics of the dissociation of metal porphyrins for various solvent acidities and temperatures are determined. The complexes are soluble in con centrated H2SO4 in the molecular form or in the form of an ion-molecule ass ociation species with the proton of the solvent. The stability, solute spec ies, and the mechanism of dissociation of the metal porphyrin are controlle d by the presence or absence of an acido ligand in the first coordination s phere and by the configuration of the macrocycle.