REVERSIBLE HYDROCARBON ACTIVATION BY RHODIUM PHTHALOCYANINE DIMER [(R(8)PC)RH](2) (R(8)PC(2-)=DIANION OF 1,4,8,11,15,18,22,25-OCTA-N-PENTYLPHTHALOCYANINE)

We have synthesized four rhodium-phthalocyanine complexes: (R(8)Pc)(C6H5CN)ClRh, [(R(8)-Pc)(MeOH)(2)Rh]Cl, [(R(8)Pc)Rh](2) (1), and (R(8)PcH)RhRh(R(8)Pc)H (2). In this notation R(8)Pc(2-) is the dianion of 1,4,8,11,15,18,22,25-octa-n-pentylphthalocyanine. The Rh-Rh bonded dimer 1 reacts with H-2 to give 2, and it activates the C-H bonds of toluene and the R(8)Pc(2-) ligand at temperatures of 150 degrees C. It also catalyzes the H-D exchange between the R(8)Pc(2-) ligand and D2O and between the ligand and toluene-d(8). Although all of the H's of the R(8)Pc(2-) ligand are activated, only the benzylic H's of toluene are activated. A radical mechanism, initiated by homolysis of 1, is proposed for these reactions.