CRYSTAL-STRUCTURE AND MAGNETIC-SUSCEPTIBILITY OF COPPER(II) CHLORIDE TETRAMETHYLSULFOXIDE [CUCL2(TMSO)] AND COPPER(II) CHLORIDE MONODIMETHYLSULFOXIDE [CUCL2(DMSO)] - FERROMAGNETIC SPIN-1/2 HEISENBERG LINEAR-CHAINS

The crystal structures of the title compounds [C4H8SO (TMSO), C2H6SO (DMSO)] have been determined. The TMSO salt is orthorhombic [space group Pbca, a=13.844(10), b=6.418(12), and c=17.480(16) while the DMSO salt is monoclinic [space group P21c, a=7.774(1), b=13.557(3), c=6.475(1) and β=103.83(1) °]. Each contain linear chains of Cu ions with three bridging ligands (2 C1, 1 O) between each pair of Cu ions. The bridging Cu-L-Cu angles are ∼ 87 ° for the symmetrical bridges and ∼ 80° for the asymmetrical bridges. In each salt, the copper coordination geometry is severely distorted from octahedral with four short Cu-ligand bonds (three chlorine and one oxygen) and two long Cu-ligand bonds (one chlorine and one oxygen). Adjacent chains are well isolated from each other by the sulfoxide groups in one direction, but short sulfur-sulfur contacts occur between adjacent chains in the other direction. The susceptibility of the salts has been measured between 2.0 and 300 K on a PAR vibrating-sample magnetometer and on a Faraday balance. The high-temperature data show positive deviation from Curie behavior, indicative of ferromagnetic coupling. However, considerable magnetic interactions between chains exist and the χT vs T plots show maxima at low temperature. The data have been analyzed with several one-dimensional models. The best fit is obtained with an Heisenberg linear chain with ferromagnetic interaction (Jk=39°K, TMSO; Jk=45°K, DMSO) with a mean-field correction for the antiferromagnetic interchain interactions (ZJ′k=-1.6°K, TMSO; ZJ′k=-4.0°K, DMSO). Thus, the relevant ratio defining the ideality of the system, JJ′, is ∼ 50 for the TMSO salt and ∼ 25 for the DMSO salt. © 1979 The American Physical Society.