Solvothermal syntheses and structural characterisation of three isostructural 3D metal-malate coordination polymers:: {[M(C4H4O5)(H2O)]•H2O}n (M = CoII, NiII, CoII/NiII)

Three isostructural coordination polymers with the general formula ([M(C4H4O5)(H2O)](H2O)-H-.)(n) [M = Co-II (1), Ni-II (2) and 1/3Co(II) + 2/3Ni(II) (3), C4H4O5 = Hmal(2-), malate dianion] have been designed and synthesised via solvothermal routes. In these compounds, the malate acts as the unique quinquedentate ligand with all five oxygen atoms participating in the coordination. The M-II ions are interconnected via alpha- and beta-carboxyl groups from the malate ligands to generate zigzag chains and planes which are further linked together by the P-carboxyl groups leading to the 3D open frameworks. Variable temperature magnetic susceptibility measurements indicate the occurrence of antiferromagnetic (1), ferromagnetic (2) and ferrimagnetic (3) interactions between the M-II ions mediated by the skew-skew carboxylate bridges., ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).