Molecular and Electronic Structures of Homoleptic Nickel and Cobalt Complexes with Non‐Innocent Bulky Diimine Ligands Derived from Fluorinated 1,4‐Diaza‐1,3‐butadiene (DAD) and Bis(arylimino)acenaphthene (BIAN)

Abstract

AbstractThe diimine complexes with bulky fluorinatedN‐substituents [NiII(FDAD)2]1and [CoII(FDAD)2]2[FDAD =N,N′‐bis(pentafluorophenyl)‐2,3‐dimethyl‐1,4‐diaza‐1,3‐butadiene]as well as diimine complexes with extended π system [NiII(FBIAN)2]3and [CoI(FBIAN)3]4(FBIAN = bis[N‐{3,5‐bis(trifluoromethyl)phenyl}imino]acenaphthene) were synthesized. Compound4represents the first complex with three bis(imino)acenaphthene ligands synthesized so far. The molecular structures of the complexes1–4were determined by X‐ray crystallography at 193 K. Complexes1,2and3comprise the divalent metal ions with pairs of radical monoanionic ligands, whereas4is best described as a cobalt(I) complex with two neutral (FBIAN)0and one (FBIAN)1–ligand in the radical monoanionic form. The electronic structures of the paramagnetic cobalt complexes2and4were investigated by SQUID measurements and X‐band EPR spectroscopy. Both complexes possess a doublet ground state, with electron density located mostly in the metal d‐orbitals. The doublet–quartet energy gap for4was established to be 159 cm–1. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)