Synthesis and characterization of nanoclusters: Inorganic-organic hybrid copper and cobalt containing arsenotungstates(III) with lone pair on heteroatom incorporating bidentate N-donating ligands

Abstract

Three inorganic-organic hybrid nanoclusters of copper and cobalt containing arsenotungstates with lone pair on heteroatom have been synthesized under mild reactions conditions. All the compounds have been characterized by single crystal X-ray diffraction, Fourier transform infrared, UV/visible spectroscopy, thermogravimetric and field emission scanning electron microscopic (FE-SEM) analysis. The compound [NaRb{Cu(phen) (H₂O)₂Cl}₂][{Cu(phen)(H₂O)}₂{Cu(phen) (H₂O)Cl}₂{Cu₂As₂W₁₉O₆₇(H₂O)] (1a) is a sandwiched type arsenotungstate with two copper atoms in square planar environment in the belt region. The polyanion-1 is decorated by four copper phenanthroline complexes through a terminal oxygen atom of the polyanion. In addition, two other cobalt containing inorganic-organic hybrid lone pair containing arsenotungstates(III) with 1,10-phenanthroline [NaRbCo(phen)₃][{Co(phen)(H₂O)₃}CoAs₂W₂₀O₆₇(H₂O)₃] (2a) and 2,2’-bipyridine[Na₃RbCo(2,2-bipy)₃][CoAs₂W₂₀O₆₇(H₂O)₃] (3a) has also been synthesized under mild conditions. The polyanion (2) is a mono cobalt substituted sandwiched type structure that is decorated by a cobalt phenanthroline complex attached to the polyanion through a terminal oxygen atom. Meanwhile the other complex (3) is also a monocobalt substituted sandwiched type structure which contains a cobalt 2,2’-bipyridine complex in the cationic part. Polyanion-1 shows intermolecular π-π stacking interaction between the phenanthroline ligand in the cationic part and one that is attached directly to the polyanion. The compounds are also characterized by FE-SEM analysis and the compound 3a shows ultra- smooth cuboids with grain size in the range of 1 to several micrometer though some very small irregular particles with the size of a few micrometer were also observed.