Hydrothermal Synthesis And Crystal Structure And Properties Of Transition-metal Molybdenum Selenite

Inorganic open-framework materials have been receiving extensive attention not only because of structural variety, but also potential applications in many fields such as atalysis, adsorption, magnetic, optical materials and ion exchange. Metal selenites can adopt many unusual structures due to the presence of the stereochemically active lone-pair electrons. The asymmetric coordination polyhedron adopted by Se^â…£ atom may result in noncentrosymmetric structures with consequent interesting physical properties, such as nonlinear optical second-harmonic generation (SHG). Based on the systematic investigation on the literature in inorganic open-framework materials research, we adopted hydrothermal synthesis to obtain three novel containing-molybdenum(â…¥) mixed-transition metal selenite oxides.Among the three mixed-transition metal selenite oxides, the structures of compounds, {MnSeMoO₆(H₂O)}_∞and {Zn₂SeMoO₇)_∞(1-2) have been determined by single crystal X-ray diffraction, they feature a 3D framework structures. The coordination mode of Mo atom is different in (1-2). In compound 1, the Mo atoms are octahedrally coordinated by six oxygen atoms, whereas Mo atoms in (2) tetrahedrally coordinated by four oxygen atoms. The structure of compound (3) has not been determined because of unproper crystal size. It has similar IR spectra to those of(1)and(2).In conpound (4) 2D Cu -O layers linked by {Cu(2)₂O₈} forming 3D Cu-O-Cu framework. The selenium atoms are grafted onto the 3D Cu-O-Cu framework, resulting in 12-ring channels with a dimension of 10.364(27)×8.589(2) into a three-dimensional inorganic polymer.Conpound h-MoO₃·1/3H2O (5) was accidently obtained in our attempting to synthesize X-Se-Mo-O quaternary compounds。The structure of compound (5) is based on double chains of MoO₆ octahedra bonded together with oxygen atom into a three-dimensional frameworks and porous molybdenum trioxide, in which two kinds of 1D tunnel exist. The one tunnel consists of hexagonal 12-member-ring defined by twelve {MoO₆} octahedra, where the free water molecules were located. The other consists of 3-member-ring defined by three {MoO₆} octahedra. Additionally, IR and Raman apectra were employed to compare its structure with the known similar compounds.Besides X-Se-Mo-O system, we have attempted to research X-Sb-Mo-O system and lead to a new polyoxometalate compound, K₆[Mo₄Sb₆(OH)₁₂O₂₄]·6H₂O 6. X-ray structural analysis shows that the polyanion {Mo₄Sb₆(OH)₁₂O₂₄}^6-has a S4 molecular symmetry and built of an unusual {Sb₆O₁₆(OH)₁₂} framework capped with four segregated {MoO₂} groups. Additionally, its IR, UV-vis and electrochemistry behaviour have been studied.