SELECTIVE AXIAL BOND-CLEAVAGE OF A HIGH-VALENT METALLOID PORPHYRIN FOLLOWING CHARGE-TRANSFER EXCITATION

The antimony(V) complex [(TPP)Sb(CH3)(2)]PF6 with TPP = 5,10,15,20-tet raphenylporphyrin contains air and moisture stable sigma alkyl bonds. Short-wavelength irradiation of this compound under anaerobic conditio ns in acetonitrile solution induces a stepwise photoaquation process t hat finally yields dihydroxo antimony(V) tetraphenylporphyrin and meth ane as permanent reaction products. The population of a charge transfe r excited state that selectively activates the axial coordination sphe re of the porphyrin complex is proposed.