Syntheses, structures and magnetic properties of five coordination polymers derived via in situ metal–ligand reactions of 2-phenyl-malonic acid

Four new coordination polymers, namely [Co3(4,4′-bpy)4(pa)4](NO3)2(4,4′-bpy)(H2O)3.5 (1), [Co(4,4′-bpy)(pa)2(H2O)2](paH)2 (2), [Zn3(4,4′-bpy)4(pa)4](NO3)2(paH)(H2O)2.5 (3), [Cu(4,4′-bpy)0.5(ba)2] (4), as well as one known compound [Cu(pyz)0.5(ba)2] (5) (4,4′-bpy=4,4′-bipyridine; paH=phenylacetic acid; baH=benzoic acid; pyz=pyrazine) have been hydrothermally prepared via metal ion-dependent in situ metal–ligand redox reactions of 2-phenyl-malonic acid (2-phmalH2). Among them, 1, 2 and 3 contain paH and pa as the decarboxylated products of 2-phmalH2, while 4 and 5 contain the redox product baH instead of paH. This results show that the decarboxylation occurs easily to 2-phmalH2 under hydrothermal condition, while an in situ metal/ligand redox reaction undergoes in the presence of copper(II) ion. Compound 1 bearing well isolated, carboxylate-bridged linear trimeric Co3II subunits shows intracluster antiferromagnetic interaction (J=−9 K) and no long-range magnetic ordering down to 2 K.