HIGHLY STABILIZED LOW-SPIN IRON(III) AND COBALT(III) COMPLEXES OF A TRIDENTATE BIS-AMIDE LIGAND 2,6-BIS(N-PHENYLCARBAMOYL)PYRIDINE - NOVEL NONMACROCYCLIC TETRAAMIDO-N COORDINATION AND 2 UNUSUALLY SHORT METAL-PYRIDINE BONDS

Two novel low-spin complexes, [Et4N][FeL2.15H(2)O (1) and [Et4N[CoL2]. 2H2O (2) (L is a deprotonated bis-amide ligand), have been synthesized and characterized. Four relatively longer equatorial M-N-amide bonds and two significantly shorter axial M-N-py bonds are the noteworthy fe atures of their X-ray structures. EPR and (34-300 K) magnetic studies of 1 confirm its low-spin character. Cyclic voltammetric studies revea l a highly stabilized M(III) state. For I a linear correlation between the Fe(III)-Fe(II) reduction potentials and the reciprocal of solvent dielectric constants is obtained.