Theoretical description of the magnetic properties of μ3-hydroxo bridged trinuclear copper(II) complexes

Abstract

A theoretical study of the magnetic properties, using density functional theory, of a family of trinuclear μ3-OH copper(II) complexes reported in the literature is presented. The reported X-ray crystal structures of [Cu3(μ3-OH)(aat)3(H2O)3](NO3)2·H2O (HUKDUM), where aat: 3-acetylamine-1,2,4-triazole; [Cu3(μ3-OH)(aaat)3(H2- SO4)(HSO4)(H2O)] (HUKDOG), where aaat: 3- acetylamine-5-amine-1,2,4-triazole; [Cu3(μ3-OH)(PhPyCNO) 3(tchlphac)2] (HOHQUR), where PhPyCNO: phenyl 2-pyridyl-ketoxime and tchlphac: acid 2,4,5-trichlorophenoxyacetic; [Cu3(μ3-OH)(PhPyCNO)3(NO3)2(CH3OH)] (ILEGEM); [Cu3(μ3-OH)(pz)3(Hpz)3(ClO4)2] (QOPJIP), where Hpz0pyrazole; [Cu3(μ3-OH)(pz)3(Hpz)(Me3CCOO) 2] 2Me3CCOOH (DEFSEN) and [Cu3 (μ3-OH)(8- amino-4-methyl-5-azaoct-3-en-2-one)3][CuI3] (RITXUO), were used in the calculations. The magnetic exchange constants were calculated using the broken-symmetry approach. The calculated J values are for HUKDUM J10 −68.6 cm−1, J20−69.9 cm−1, J30−70.4 cm−1; for HUKDOG, J10−73.5 cm−1, J20−58.9 cm−1, J30−62.1 cm−1; for HOHQUR J10−128.3 cm−1, J20−134.1 cm−1, J30−120.4 cm−1; for ILEGEM J10−151.6 cm−1, J20−173.9 cm−1, J30−186.9 cm−1; for QOPJIP J10−118.3 cm−1, J20−106.0 cm−1, J30 −120.6 cm−1; for DEFSEN J10−74.9 cm−1, J20−64.0 cm−1, J30−57.7 cm−1 and for RITXUO J10−10.9 cm−1, J20 +14.3 cm−1, J30−35.4 cm−1. The Kahn-Briat model was used to correlate the calculated magnetic properties with the overlap of the magnetic orbitals. Spin density surfaces show that the delocalization mechanism is predominant in all the studied compounds.