Synthesis, crystal structure and magnetic properties of [Cu(mal)(abpt)(H2O)].3/2H2O and [Cu2(sq)(abpt) 2].2H2O (mal = malonate, sq = squarate, abpt = 4-amino-3,5-di-2-pyridyl-4H-1,2,4 triazole)

Two new mixed-ligand complexes of formula [Cu(mal)(abpt)(H2O)].3/2H2O (1) and [Cu2(sq)(abpt)2].2H2O (2) [mal = malonate, abpt = 4-amino-3,5-di-2-pyridyl-4H-1,2,4 triazole and sq = squarate], have been prepared and characterized by X-ray crystal structure determination and magnetic studies. Complex 1 crystallizes in the monoclinic system, space group C2/c, with a = 14.0086(2) Å, b = 10.0980(2) Å, c = 25.630(4) Å; β = 97.5900(10) o, and Z = 8. Complex 2 crystallizes in the triclinic system, space group P-1 with a = 7.5696(15) Å, b = 8.4697(17) Å, c = 11.049(2) Å; β = 93.00(3)o, α = 96.98(3), γ = 90.111(3) and Z = 1. Complex 1 consist of a neutral mononuclear [Cu(mal)(abpt)(H2O)] unit and water molecule of crystallization in a distorted square pyramidal coordination sphere, while complex 2 is viewed as being made up of [Cu(sq)(abpt)2] units with the squarato ligand bridging the two copper(II) cations. Variable temperature magnetic behaviour of the complexes reveals the existence of weak antiferromagnetic interaction for complex 1 and weak ferromagnetic intrachain interaction for complex 2.