X-ray structure of poly[aquabis(benzimidazole-N3)copper(II)-μ-trans-2-butene-1,4-dicarboxylato-O,O':O",O"'] (I) and magnetic and spectroscopic characterization of I and the isostructural copper(II)-μ-adipato complex II

The title compounds [Cu(H2O)(C7H6N2)(2)(C6H6O4)] (1) and isostructural [Cu(H2O)(C7H6N2)(2)(C6H8O4)1 (H) are the rarely observed seven-coordinate Cu(II) complexes of C, elongated square-pyramidal geometry with a double-capped base by two very long Cu-O(carboxylate) bonds, The valences of Cu N and Cu-O bonds in I and II have been computed to confirm the assumed Cu(II) coordination number. The hydrogen bond system and Cu (. . .) Cu intra- and interpolymeric chain spacing in I and 11 have been analyzed to explain their magnetic properties. The magnetic susceptibility measurements of I and 11 in the range 1.7-300 K suggest weak antiferromagnetic interaction between Cu(II) centres. The EPR and d-d spectra of both complexes have been measured and analyzed. (C) 2002 Elsevier Science Ltd. All rights reserved.