Synthesis, crystal structure, spectroscopic and magnetic properties of an unprecedented three-dimensional Cu-II coordination compound of 1,2-bis(1,2,4-triazol-4-yl)ethane

A novel three-dimensional copper(II) compound of the formula [Cu-3(btre)(5) (H2O)(2)](ClO4)(6). H2O (btre = 1,2-bis(1,2,4-triazol-4-yl)ethane) has been synthesized. The structure has been solved at 150 K by single-crystal X-ra y analysis. The compound [C30H44Cu3N30O2. 6(ClO4). H2O] crystallizes in the triclinic space group P1 bar with a = 12.488(1), b = 13.195(1), c = 19.756 (2) Angstrom, alpha = 78.959(8), beta = 84.553(8), gamma = 63.869(7)degrees , V = 2868.4(5) Angstrom(3), Z = 2 (trinuclear Cu-II units), 6484 reflectio ns [I > 4 sigma(I)], R-F = 0.0581, wR(2) = 0.1214. The structure of this co ordination polymer consists of a three-dimensional net work built up from l inear trinuclear Cu-II cations of formula [Cu-3(btre)(5)(H2O)(2)](6+). This crystallographically independent unit comprises a linear array of three Cu -II ions linked by triple N1,N2-1,2,4-triazole bridges, yielding Cu1-Cu2 3. 893(1) Angstrom and Cu2-Cu3 = 3.889(1) Angstrom. These linear trinuclear Cu -II units are Linked by various pathways involving tridentate and tetradent ate bridging btre Ligands, which yields an unprecedented three-dimensional network. The Cu-II ions are weakly antiferromagnetically coupled with J = - 1.01(2) cm(-1) (based on the Hamiltonian: 1-1 = J[S-Cu1. S-Cu2 + S-Cu2. S-C u3] using the expression for the molar magnetic susceptibility S = 1/2 of a linear trinuclear system). The nature and the magnitude of the antiferroma gnetic exchange have been discussed on the basis of the structural features .