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

Abstract The diimine complexes with bulky fluorinated N ‐substituents [Ni II ( F DAD) 2 ] 1 and [Co II ( F DAD) 2 ] 2 [ F DAD = N , N′ ‐bis(pentafluorophenyl)‐2,3‐dimethyl‐1,4‐diaza‐1,3‐butadiene]as well as diimine complexes with extended π system [Ni II ( F BIAN) 2 ] 3 and [Co I ( F BIAN) 3 ] 4 ( F BIAN = bis[ N ‐{3,5‐bis(trifluoromethyl)phenyl}imino]acenaphthene) were synthesized. Compound 4 represents the first complex with three bis(imino)acenaphthene ligands synthesized so far. The molecular structures of the complexes 1 – 4 were determined by X‐ray crystallography at 193 K. Complexes 1 , 2 and 3 comprise the divalent metal ions with pairs of radical monoanionic ligands, whereas 4 is best described as a cobalt(I) complex with two neutral ( F BIAN) 0 and one ( F BIAN) 1– ligand in the radical monoanionic form. The electronic structures of the paramagnetic cobalt complexes 2 and 4 were 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 for 4 was established to be 159 cm –1 . (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)