Transition metal complexes with nitronyl nitroxides Part 2. Crystal structure and magnetism of manganese (II) compounds including radicals and their reduced derivatives

摘要

Four complexes, Mn(hfac)(2)(NITPhCl) (1), {Mn(hfac)(2)(NITPhCH3)}(6) (2), [Mn(hfac)(2)(IMHF)](2) (3), and Mn(hfac)(2)(NITF)(2). 2H(2)O (4) (hfac = hexafluoroacetylacetonate, NITPhX = 2-(4-X-phenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (X = chloro (NITPhCI), X = methyl (NITPhCH3), IMHF = 1-hydroxo-2-furfural-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole, NITF = 2-furfural-4,4,5,5-tetrame-thylimidazoline-1 -oxyl-3-oxide) have been prepared and studied. IR, EPR and variable-temperature magnetic susceptibility studies of 1-4 indicate a variety of structural types. Complexes I and 4 an probably mononuclear while 2 is hexanuclear. Complex 3 resulting, together with complex 4, from the reaction of Mn(hfac)(2).(1/2)H2O with MTF is dinuclear and includes the reduced amidino-oxide form of NITF. The structure of 3 was solved by X-ray diffraction and refined to conventional agreement indices R = 0.051 and R-w = 0.052. It crystallizes in the triclinic, P (1) over bar space group with a=10.463(1), b=10.316(2), c=13.224 (2) Angstrom, alpha=108.45(2), beta=106.48(2), gamma=103.&0(2)degrees, Z=1. Two IMHF ligands bridge the two manganese(II) ions of 3 through their amidino-oxide oxygen atoms affording a small intramolecular antiferromagnetic interaction. (C) 1998 Elsevier Science S.A. All rights reserved. [References: 30]