The Electronic Structure of (Diiminopyridine)cobalt(<scp>I</scp>) Complexes

Abstract

Abstract DFT calculations show that square‐planar LCo I R complexes of a diiminopyridine ligand are best regarded as containing low‐spin Co II antiferromagnetically coupled to a ligand radical anion. The lowest triplet state, corresponding to a 3d ⇄π* excitation, is calculated to be only a few kcal/mol above the ground state, and is thermally accessible. The anomalous 1 H NMR chemical shifts of the LCoR complexes are suggested to be due to thermal population of the triplet state at room temperature. (© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2004)