Transition metal complexes with nitronyl nitroxides Part 1. Crystal structure and properties of square-planar trans radical-copper(II)-radical complexes

Two novel complexes, [Cu(NITPhOMe)(2)Cl-2] (1) and [Cu(NITPhCl)(2)(pfpr)(2)] (2) (NITPhX = 2-(4-X-phenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide, (X = methoxy (NITPhOMe), X = chloro (NITPhCl)), (pfpr = CF3CF2CO2-)) have been prepared and studied. The complexes have been characterized by elemental analysis, IR, UV-Vis and EPR spectroscopy, and X-ray crystal structure analysis. Both complex molecules crystallize in the triclinic, P (1) over bar space group with a=8.485(1), b=9.058(2), c=11.218(3) Angstrom, a=104.02(2), beta = 109.67(2), gamma = 95.30(2)degrees, Z = 1 (1) and a = 9.701(1), b = 12.256(2), c = 9.593(1) Angstrom, alpha = 107.54(2), beta = 114.22(2), gamma = 92.18(2)degrees, Z = 1 (2). The structures have been refined to conventional agreement indices R = 0.045 (1) and 0.032 (2). In both complexes, the central copper atom has a square planar ligand environment including two NITR radicals. Magnetic measurements show that the 1/2-1/2-1/2 spin systems of both complexes are in a doublet state at 300 K. Antiferromagnetic intermolecular interactions afforded by O ... N contacts between the NITPhOMe ligands of adjacent [Cu(NITPhOMe)2Cl2] molecules operate in complex 1. (C) 1998 Elsevier Science S.A. All rights reserved.