Journal of Electroanalytical Chemistry, Vol.469, No.1, 84-87, 1999
Electrochemical study of tetraphenylporphinato-iron(III)-thiolate complexes, NH center dot center dot center dot S hydrogen bonding in the cytochrome P-450 model system
Porphinato-iron(III)-thiolate complexes, [Fe-III(TPP){S-2-(4-X-C6H4CONH)C6H4}] (TPP = tetraphenylporphyrin, X = H, OMe and NO,), were synthesized as models of cytochrome P-450. The complex, [Fe-III(TPP)(S-2-PhCONH-C6H4)], shows a positively shifted Fe(III)/Fe(II) redox potential in dichloromethane at -0.901 V versus Cp,Fe compared with the corresponding redox potential of [Fe-III(TPP)(S-Ph)] (-1.120 V vs. Cp2Fe) under the same conditions. Such a positive shift of redox potential is considered to be caused by the formation of an intramolecular (NHS)-S-... hydrogen bond. The existence of this (NHS)-S-... hydrogen bond was confirmed by infrared spectroscopy.