Novel copper complexes based on the thiocyanate bridge - Synthesis, X-ray studies and magnetic properties

Three novel compounds {[Cu(bpzm)(SCN)][Cu(bpzm)(MeOH)][Cu(SCN)(4)]}(n) (1a), {[Cu(2)(bpzm)(2)(mu-SCN) (SCN)(3)]}(n) (1b) and [Cu(2)(mu-SCN)(2)(SCN)(2)(dPa)(2)] (2) have been obtained in one-step self-assembly reaction of copper dichloride, a suitable N-N ligand (bis(pyrazol-1-yl)methane and 2,2'-dipyridylamine) and ammonium thiocyanate. For the reaction involving bis(pyrazol-1-yl)methane, an unprecedented in situ reduction of some Cu(II) ions to Cu(I) has been observed. The compound {[Cu(bpzm)(SCN)][Cu(bpzm) (MeOH)][Cu(SCN)(4)]}(n) (1a) belongs to a relatively scarce group of mixed-valence Cu(II)/Cu(I) coordination polymers with interesting polymeric architecture. It creates infinite two-dimensional structure consisting of layers extending along crystallographic plane (001), in which the cations [Cu(II)(bpzm)(SCN)](+) and [Cu(II)(bpzm)(MeOH)](2+) are connected by ions [Cu(I)(SCN)(4)](3-) through single end-to-end thiocyanato bridges. Structure 1b consists two crystallographically independent chains. The chain A has a zig-zag form and extends along the crystallographic direction [001], whereas the second chain is linear and runs along the crystallographic direction [010]. The structure 2 consists of dinuclear [Cu(2)(dpa)(2)(mu-SCN)(2) (SCN)(2)] units. Variable-temperature magnetic susceptibility measurements show very weak antiferromagnetic interactions between the paramagnetic centres Cu(II) centers inside the crystal lattices of three novel compounds. (C) 2010 Elsevier Ltd. All rights reserved.