UNUSUAL METALLOPORPHYRINS XI. FURTHER STUDIES ON RHENIUM (I) PORPHYRINS

Abstract
Experimental details are given for the preparation of two complexes of rhenium with mesoporphyrin IX dimethyl ester, Re(CO)3(H-MPIXDME) and μ-(MPIXDME)[Re(CO)3]2. The molecular geometry of these complexes is discussed and it is concluded that they do not have simple predictable structures. Three possible structures are discussed for the dirhenium complex. An empirical explanation, similar to the “eighteen electron rule” for metal carbonyls, is given as to why rhenium is in the +1 state. Porphyrin complexes containing a single atom of rhenium and an atom of another metal (Ag+, Hg++, or Pb++) were detected spectrally but not isolated. Finally the monorhenium complex is compared to the proposed intermediate in metal insertion, in which the metal sits above the porphyrin ring.