Synthesis, spectral and magnetic properties, and crystal structures of copper(II)2-methylthionicotinate adducts with chelating ligands

The synthesis and characterization of [Cu-2(2-MeSnic)(4)(H2O)(2)], [Cu(2MeS nic)(2)(en)], [Cu(en)(2)(H2O)(2)](2-MeSnic)(2) and [Cu-(dien)(H2O)(2)](2-Me Snic)(2) (where 2-MeSnic = 2-methylthionicotinate, en = ethylenediamine, di en = diethylenetriamine) is reported. The characterizations were based on e lemental analysis, infrared, electronic and EPR spectra, and magnetic susce ptibility measurements over a temperature range of 1.9-300 K. The available evidence supports a dimeric structure for [Cu-2(2-MeSnic)(4)(H2O)(2)] and for [Cu(en)(2)(H2O)(2)](2-MeSnic)(2) a tetragonal-bipyramidal environment a bout the copper(II) atom. The other two complexes were studied also by X-ra y analysis. The [Cu(dien)(H2O)(2)(2-MeSnic)(2)] crystallizes in the monocli nic system. The copper(II) atom has a square-pyramidal arrangement, with th ree nitrogen atoms of the tridentate diethylenetriamine and one water molec ule in the base of the pyramid, and the remaining water molecule occupies t he apical position. The copper(II) atom deviates from the basal plane by 0. 1164(5) Angstrom toward the water molecule in the apical position. The copp er(II) atom in [Cu(2-MeSnic),(en)] is coordinated by two symmetry-dependent nitrogen atoms of ethylenediamine and by two pairs of non-equivalently coo rdinated carboxyl oxygen atoms of two symmetry-dependent 2-methylthionicoti nates with Cu-O bond distances of 1.975(2) and 2.564(2) Angstrom, respectiv ely, resulting in a highly distorted tetragonal-bipyramidal coordination. ( C) 2001 Elsevier Science Ltd. All rights reserved.