ELECTROCHEMICAL STUDIES OF STRUCTURALLY RELATED TRIPLY-BRIDGED DINUCLEAR TRIS(BIPYRIDINE)IRON(II) COMPLEXES - AN ELECTROSTATIC MODEL FOR SITE-SITE INTERACTION

The structures and electrochemical behavior of a series of symmetric dinuclear complexes in which two iron centers are bridged by three bis[4-(4'-methyl-2,2'-bipyridinyl)]alkane ligands are presented. Square wave voltammetry was used to characterize the extent of interaction between the metal-centered halves. Because the saturated linkages preclude significant electron delocalization the observed interaction is concluded to be almost purely Coulombic in nature. Furthermore, molecular modeling and X-ray crystallographic data confirm that the iron-iron separation in the complex containing three methylenes in the linkages is nearly identical to the iron-iron separation in the complex containing two methylenes in the linkages. Using a simple electrostatic model and employing structural parameters obtained from X-ray data and molecular modeling, the electrochemical trends within the series are interpreted.