Weaker magnetic interactions of oxalato-copper(II) binuclear compounds: synthesis, spectroscopy, crystal structure and magnetism

Two binuclear copper(II) compounds, Cu-2(tacn)(2)(mu-ox)(ClO4)(2) (I) and [Cu-2(bdpm)(2)(H2O)(2)(mu-ox)](ClO4)(2) . H2O (II), where tacn = 1,4,7-triazacyclononane, ox = oxalate dianion, bdpm = bis(3,5-dimethylpyrazol-1-yl)methane, have been synthesized and characterized by X-ray diffraction. Each copper atom of compound I has a 4 + 1 + 1 elongated pseudo-octahedral environment; the copper atoms have distorted square pyramidal geometry in compound II. The magnetic susceptibilities (300-4 K) indicated that the binuclear copper(II) cores were antiferromagnetically coupled (2J = - 41 cm(-1) for compound I, 2J = - 102 cm(-1) for compound II). The weakness of the interactions for both compounds is discussed on the basis of the structural features. (C) 2000 Elsevier Science Ltd All rights reserved.