A nearly symmetric trinuclear chromium(III) oxo carboxylate assembly: preparation, molecular and crystal structure, and magnetic properties of [Cr3O(O2CPh)(6)(MeOH)(3)](NO3) center dot 2MeOH

摘要

Complex [Cr3O(O2CPh)(6)(MeOH)(3)](NO3) (.) 2MeOH (1 (.) 2MeOH) has been synthesized from the one-pot reaction between Cr(NO3)(3) (.) 9H(2)O and NaO2CPh in MeOH. The structure of the complex has been solved by single-crystal X-ray crystallography. It crystallizes in the monoclinic space group P2(1) with a = 14.716(6) Angstrom, b = 22.569(8) Angstrom, c = 15.755(6) Angstrom, beta = 95.02(1)degrees, V = 5212.5 (4) Angstrom(3) and Z = 4. Although the cation does not possess any crystallographically imposed symmetry element, its {Cr-3(mu(3)-O)} core is nearly symmetric. Each Cr-III...Cr-III vector is further bridged by two eta(1):eta(1):mu(2) benzoates, with a terminal MeOH molecule completing octahedral coordination at each metal ion. The crystal structure consists of layers that are parallel to (0 10) crystallographic plane and are formed through pi-pi stacking interactions and hydrogen bonds. Variable-temperature magnetic susceptibility and solid-state H-1 NMR studies indicate that the total spin value of the ground state is 1/2. EPR experiments reveal the existence of a distribution of trimers with axial anisotropy in the g tensor. (C) 2004 Elsevier B.V. All rights reserved.