STRUCTURE AND PROPERTIES OF TETRAPHENYLPORPHINATE IRON(III) COMPLEXESWITH AN INTRAMOLECULAR NH-CENTER-DOT-CENTER-DOT-CENTER-DOT-O PHENOLATE HYDROGEN-BOND

Thermodynamically stable tetraphenylporphinate Fe(III) arenethiolate o r arenolate complexes having NH ... S or NH ... O hydrogen bonds on th e axial ligand, [Fe-III(tpp) {S-2,6-(CF3CONH)(2)C6H3}] (tpp = tetraphe nylporphinato), [Fe-III(tpp) (S-2-CF3CONHC6H4)], [Fe-III(tpp) {O-2,6-( CF3CONH)(2)C6H3}] and [Fe-III(tpp)(O-2-CF3CONHC6H4)], were synthesized and characterized as models of cytochrome P-450 and catalase. The NH ... S or NH ... O hydrogen bonds in both model complexes contribute to the positive shift of the redox potential in the Fe(III)/Fe(II) compl exes compared with a simple benzenethiolate or a phenolate complex. A mild reductant, (NEt4)BH4, can easily reduce the model complexes to Fe (II) species which are thermodynamically unstable. The direct oxidatio n of these model complexes in the presence of PhIO in dichloromethane at room temperature results in decomposition to give the mu-oxo comple xes. (C) 1998 Elsevier Science S.A. All rights reserved.