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

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) (H 2 O) 2 Cl} 2 ][{Cu(phen)(H 2 O)} 2 {Cu(phen) (H 2 O)Cl} 2 {Cu 2 As 2 W 19 O 67 (H 2 O)] (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)(H 2 O) 3 }CoAs 2 W 20 O 67 (H 2 O) 3 ] (2a) and 2,2’-bipyridine[Na 3 RbCo(2,2-bipy) 3 ][CoAs 2 W 20 O 67 (H 2 O) 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.