Synthesis and structural and magnetic characterization of discrete phenolate and imidazolate bridged Gd(III)-M(II) [M = Cu, Ni] dinuclear complexes

Three dinuclear complexes formed by the reaction of Gd(hfa)(3) (hfa is hexa fluoroacetylacetonate) with Schiff base complexes of Cu(II) and Ni(II) have been synthesized and characterized. The crystal structures of the complexe s [Gd(hfa)(3)M(prpen)] {M = Cu(II (1)), Ni(II) (2)} are reported. (H(2)prpe n is the Schiff base derived from the condensation of 2 equiv. of 2-hydroxy propiophenone and 1 equiv. of ethylenediamine.) Both 1 and 2 are discrete d inuclear complexes consisting of an eight coordinate Cd atom which is bridg ed to four coordinate M(II) via both phenolate oxygen atoms of the prpen li gand. The crystal structure shows there is no tendency toward dimerization between adjacent Cu(II) Schiff base units in 1. Cryomagnetic measurements s how a ferromagnetic interaction between Gd(III) and Cu(II) in 1 as predicte d by theory with J = 1.91 cm (- 1). The reaction of Gd(hfa), with Ni(L) (H2 L is the Schiff base derived from the condensation of 1 equiv. each of 5-ch lorobenzophenone, 1,2-diaminobenzene, and 5-methyl-4-imidazolecarboxaldehyd e) produced Gd(hfa),Ni(L) (3) in which imidazolate is available to bridge G d(III) and Ni(II). (C) 2001 Elsevier Science B.V. All rights reserved.