Crystal structure and magnetic properties of the single-mu-chloro copper(II) chain [Cu(bipy)Cl-2] (bipy = 2,2 '-bipyridine)

The crystal and molecular structure of the copper(II) chain [Cu(bipy)Cl-2] (1) (bipy = 2,2'-bipyridine) has been determined by X-ray diffraction metho ds. The crystal structure of 1 consists of neutral single chloro-bridged co pper(II) chains with alternating shea and long Cu-Cl distances through a sc rew axis parallel to a. The copper surrounding is best described as distort ed square pyramidal, the equatorial plane being built by the two nitrogen a toms of the chelating bipy and two chlorine atoms tone terminal and the oth er bridging), whereas the apical position is filled by the bridging chlorin e atom from the symmetry-related adjacent unit. The equatorial Cu-Cl bonds (2.291(3) and 2.259(3) Angstrom) are shorter than the axial one (2.674(3) A ngstrom). The intrachain copper-copper separation is 4.010(3) Angstrom wher eas the shortest interchain copper-copper distance is 8.381(3) Angstrom. Th e magnetic properties of 1 have been investigated in the temperature range 1.8-300 K. They reveal the occurrence of a weak intrachain antiferromagneti c coupling, J = -2.3 cm(-1) (uniformly-spaced linear chain of local spin S = 1/2). This value is compared to those of related mono- and di-chloro-brid ged copper(II) polymers and the available magneto-structural data are discu ssed in the framework of a simple orbital model. (C) 1999 Elsevier Science S.A. All rights reserved.