Magneto-structural correlations in a new oxalato-bridged Cu(II) alternating-exchange spin-chain compound

Abstract

A new oxalato-bridged copper(II) compound, Cu(ox)(pyOH)•H 2 O (ox = oxalate, pyOH = 3-hydroxypyridine), has been synthesized and characterized by x-ray diffraction and magnetic susceptibility measurements. The Cu(II) ions are bridged by oxalate molecules with two different arrangements alternating along a chain parallel to the b-axis. To the best of our knowledge, this is the first example of a metal-oxalate chain with such a combination of oxalate bridges. Due to the specific structural properties, the magnetic susceptibility was analysed in the framework of an alternating-exchange spin-chain. From a least-squares fit, an antiferromagnetic coupling constant J 1 = (442 ± 5) K and an alternation parameter α = 0.13 ± 0.06 were derived, which classify Cu(ox)(pyOH)•H 2 O as a strongly dimerized spin-chain compound. It is argued that the strength of the magnetic coupling is mainly determined by the displacement of the Cu(II) ions out of the basal plane of the local Cu environment.

Alternating Ferro/Antiferromagnetic Copper(II) Chain Containing an Unprecedented Triple Formato/Hydroxido/Sulfato Bridge

“…In this kind of system, special attention has been addressed to coordination architectures that include multiatomic bridging ligands (MABLs). Thus, MABLs such as oxalate − azide − or 2,2′-bipyrimidine (bpym) − have been extensively used in magneto-structural studies because of their remarkable ability in mediating magnetic interactions between paramagnetic centers as well as the variety of dimensionalities (from both structural and magnetic points of view) and topologies that they can originate when adopting different coordination modes. Despite the variety of bpym-including ternary systems characterized, those that include carboxylate groups are relatively uncommon.…”

Copper(II) complexes of open-chain thioether ligands terminated by salicylaldimine functionality*This article has a companion paper in this issue (doi: 10.1139/v11-081).

“…There is a larger deviation for angles expected to be close to 180°with the average being 27.65(8)°and the larger being 30.81 (8)°at N(1)-Cu-N(2). These are larger deviations than those in I and arise presumably because of a shorter length of the loop of ligand joining N(1) and N(2) in III compared with I.…”

“…[1][2][3][4][5] Although the nuclearity of complexes being reported continues to rise, 6,7 much that is of fundamental significance can be learned from simple systems, 8 the best representatives of which may well be binuclear copper(II) species. For example, the effects of certain specific types of ligands or atoms bridging between pairs of metal atoms are now well understood, but the list of those bridging atoms or ligands is still comparatively small.…”