EFFICIENT SYNTHESIS OF UNSYMMETRICAL TRANSITION METALLOPORPHYRIN DIMERS UNDER MILD CONDITIONS

New ethane-bridged unsymmetrical heterodimers of octaethylporphyrin co ntaining transition metal ions (Mn and Fe) have been synthesized throu gh a facile stepwise metallation - demetallation process under mild co nditions. The synthetic strategy includes initial predominant insertio n of Zn into one of the two porphyrin rings of free-base 1, followed b y further incorporation of Mn or Fe into another porphyrin ring giving heterometallic dimers (4, 5) and the subsequent removal of Zn yieldin g free base - transition metal dimers (6, 7).