Hydrothermal synthesis and characterization of one dimensional chain structures of monolacunary Keggin polyoxoanions substituted with copper

Abstract

Two novel polymeric polyoxometallates constructed from transition metal substituted heteropolytungstates, [(4,4′bpyH2)2(4,4′bpyH)][PCuW11O39]·H2O (1), and [(4,4′bpyH2)(pyH)3][PCuW11O39]·2H2O (2), (4,4′bpy=4,4′bipyridine, py=pyridine) have been synthesized under hydrothermal conditions and characterized by IR, TGA, single crystal X-ray diffraction and magnetic measurements. The product formation showed a high sensitivity toward experimental factors including pH and stirring. Compounds 1 crystallizes in the monoclinic space group P2(1)/n with a=13.503(3)Å, b=26.726(5)Å, c=15.168(3)Å, β=99.61(3)° and Z=4. The second compound also crystallizes in space group P2(1)/n, but with a=13.519(3)Å, b=20.431(4)Å, c=18.655(4)Å, β=96.52(3)° and Z=4. Compound 1 exhibits a zigzag chain structure, while compound 2 exhibits a straight chain structure. Compound 2 is the first example of a polyoxometallate containing 1D chains of transition-metal-substituted heteropolytungstate designed with two significantly different organic units as the countercations. The Cu2+ ions in 1 exhibit paramagnetic behavior.