ELECTROCHEMISTRY OF NEW SIGMA-BONDED METAL(III) COMPLEXES WITH TETRAPYRROLE LIGANDS - REACTIONS OF (ETIOPC)M(C6H5) AND (ETIOPC)FECL WHERE M=FE OR IN AND ETIOPC IS THE DIANION OF 7,12,17-TETRAETHYL-3,6,13,16-TETRAMETHYLPORPHYCENE

The electrochemical reactivity of the first synthesized a-bonded metal loporphycenes is reported. The investigated compounds are represented as (EtioPc)M(C6H5) where M = Fe or In and EtioPc = the dianion of 7,12 ,17-tetraethyl-3,6,13,16-tetramethylporphycene Each compound was exami ned as to its redox properties in dichloromethane, benzonitrile, or py ridine, and the results of these studies are compared to data for (Eti oPc)FeCl and (EtioPc)In(C6H5) under similar solution conditions. Both sigma-bonded derivatives undergo two one-electron reductions at the co njugated pi ring system. This was expected in the case of indium but n ot in the case of iron which is the first reported example where a mon omeric iron(m) porphyrin-like molecule is reduced at the ring rather t han at the metal center. (EtioPc)Fe(C6H5) also undergoes three one-ele ctron oxidations, similar to what has been reported for (OETPP)Fe(C6H5 ) where OETPP is the dianion of octaethyltetraphenylporphyrin. The fir st oxidation of(EtioPc)Fe(C6H5) occurs at the iron center to give [(Et ioPc)Fe-IV(C6H5)](+), which is characterized by UV-visible spectroscop y prior to migration of the phenyl group and demetalation to give (N-C (6)H(5)EtioPc)H as a final product. Assignments of the electron transf er sites for oxidation and reduction of (EtioPc)Fe(C6H5) are based bot h on spectroelectrochemical data for this compound and on comparison o f its electrochemical behavior to that of (EtioPc)FeCl and (EtioPc)In( C6H5).