Preparation, crystal structures and magnetic properties of three thiocyanato-bridged copper(II) complexes with 2,2′-biimidazole or 2-(2′-pyridyl)imidazole as terminal ligands

The synthesis, crystal structures and variable temperature magnetic investigation of three Flew thiocyanato-bridged copper(II) complexes with 2,2'-biimidazole (H(2)bim) or 2-(2'-pyridyl)imidazole) (pyim) as coligands, {[Cu(H(2)bim)(2)][Cu(H(2)bim)(NCS)(2)(SCN)(0.6667)(NO3)(0.3333)](2)} center dot 2H(2)O (1), [Cu(H(2)bim)(NCS)(2)](n), (2) and [Cu(pyim)(NCS)(2)](n) (3) are reported. Complex 1 contains centrosymmetric trinuclear species where central [Cu(2)(H(2)biim)(2)](2+), cations and peripheral [Cu(1)(H(2)biim)(NCS)(2)(SCN)](-) anions are linked through single end-to-end thiocyanato bridges. Complexes 2 and 3 are made up of neutral zigzag chains of copper(II) ions linked by single (2) and double (3) end-to-end thiocyanato bridges. A bidentate H(2)bim ligand (2) or pyim (3) and a terminal N-thiocyanate group (2) complete the coordination spheres around each copper atom. The values of the intramolecular (1) and intrachain (2 and 3) copper-copper separations are 5.6143(5) (1), 5.6744(3) (2) and 6.0797(11) angstrom (3). Magnetic susceptibility measurements for 1-3 in the temperature range 1.9-295 K show the occurrence of weak intramolecular (1) and intrachain (2 and 3) antiferromagnetic interactions [J = -0.10 (1), -0.24 (2) and -0.03 cm(-1) (3), the Hamiltonians used being H = -J(S-1 - S-2 + S-2 + S-3) (1) and H = -J Sigma(i)(S-i - S-i (1)) (2 and 3)]. The magnitude and nature of these magnetic interactions are discussed in the light of the respective structures and they are compared with those reported for related systems. (C) 2009 Elsevier Ltd. All rights reserved.