Abstract

The hybrid organo-inorganic compounds [Cu 4(bipy) 4V 4O 11(PO 4) 2]nH 2O (n ∼ 5) (1), [Cu 2(phen) 2(PO 4)(H 2PO 4) 2(VO 2) · 2H 2O] (2) and [Cu 2(phen) 2(O 3PCH 2PO 3)(V 2O 5) (H 2O)]H 2O (3) which present different bridging forms of the phosphate/phosphonate group, show different bulk magnetic properties. We herein analyze the magnetic behaviour of these compounds in terms of their structural parameters. We also report a theoretical study for compound (1) assuming four different magnetic exchange pathways between the copper centres present in the tetranuclear unit. For compound (1) the following J values were obtained J 1 = +3.29; J 2 = -0.63; J 3 = -2.23; J 4 = -46.14 cm -1. Compound (2) presents a Curie-Weiss behaviour in the whole range of temperature (3-300 K), and compound (3) shows a maximum for the magnetic susceptibility at 64 K, typical for antiferromagnetic interactions. These data where fitted using a model previously reported in the literature, assuming two different magnetic exchange pathways between the four copper(II) centres, with J 1 = -30.0 and J 2 = -8.5 cm -1. © 2006 Elsevier Ltd. All rights reserved.