Syntheses, crystal structures and magnetic properties of two dicopper(II) complexes and a zigzag 1-D Cu(II) complex of a bidentate pyridyl-pyrazole ligand

Two new dinuclear copper compounds, [Cu-2(pypz)(2)(N-3)(2)(NO3)(2)](1) and [Cu-2(PYPz)(2)(OH)(2)(NO3)(2)](2), and one 1-D polymeric Cu(II) complex, [Cu(pypz)(dca)(3)](n) (3) ['pypz' = (3,5dimethyl-1-(2'-pyridyl)pyrazole) and dca = (dicyanamide)], have been synthesized and characterized crystallographically and spectroscopically. Complex 1 is pseudo-octahedral, adjacent Cu atoms are connected by a pair of mu(1,1) azido groups and the structure is stabilized by pi-pi interactions between two pyridyl moieties from two different neighboring complex molecules. Complexes 2 and 3 are square pyramidal. The hydroxo bridged complex 2 is further stabilized through H-bonding. The 1-D polymeric chain of 3 is bridged by an end-to-end dicyanamide bridge and it propagates along the crystallographic b axis, whilst the polymer chains are stacked one upon another along the crystallographic c axis. Low temperature magnetic measurement shows that complexes 1 and 2 are ferromagnetic (J values are 30.81 and 14.79 cm(-1), respectively), whereas due to larger Cu-Cu distances, complex 3 shows weak ferromagnetism. (C) 2010 Elsevier Ltd. All rights reserved.