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 new thiocyanato-bridged copper(II) complexes with 2,2′-biimidazole (H2bim) or 2-(2′-pyridyl)imidazole) (pyim) as coligands, {[Cu(H2bim)2][Cu(H2bim)(NCS)2(SCN)0.6667(NO3)0.3333]2} · 2H2O (1), [Cu(H2bim)(NCS)2]n (2) and [Cu(pyim)(NCS)2]n (3) are reported. Complex 1 contains centrosymmetric trinuclear species where central [Cu(2)(H2biim)2]2+ cations and peripheral [Cu(1)(H2biim)(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 H2bim 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) Å (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 Hˆ=-J(Sˆ1·Sˆ2+Sˆ2·Sˆ3) (1) and H = −J∑i  (Sˆi·Sˆi+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.

Single- (1 and 2) and double- (3) end-to-end thiocyanato-bridged copper(II) complexes are present in the trinuclear {[Cu(H2bim)2][Cu(H2bim)(NCS)2(SCN)0.6667(NO3)0.3333]2} · 2H2O (1) and chain [Cu(H2bim)(NCS)2]n (2) and [Cu(pyim)(NCS)2]n (3) compounds where weak intramolecular (1) and intrachain (2 and 3) antiferromagnetic interactions occur.Figure optionsDownload as PowerPoint slide