Syntheses, Structures And Properties Of Zinc Complexes Based On Vanadate/Molybdate Anions

The assembly of metal complexes by using oxometalates as ligands has currently provoked significant temporary interest.In this paper,eight zinc crystals were prepared by means of hydrothermal techniques on the basis of vanadium/molybdenium oxide anions,and they were determined structurally by X-ray single crystal diffraction and characterized by elemental analysis,IR and TG-DTA.1.Two zinc complexes based on tetrahedral {VO₄}^3- anions,[Zn₃V₂O₈(H₂O)₄] (1) and[Zn₂VO₄(OH)](2),were isolated.They exhibit particularly interesting 3D structures containing 1D Zn-O-Zn helical chains as well as ten-membered ring channels,and 2D layers constructed from unusual Zn₄O₃OH cubanes,respectively. {VO₄}^3- anions could act as a multidentate ligand for the design and formation of various open-framework structures.2.Two conformational isomers of ribbon-like zinc complexes bridged by tetrahedral {MoO₄}^2- anions,[Zn(dpa)MoO₄](3) and[Zn(dpa)MoO₄]·0.5H₂O (4·0.5H₂O)(dpa=2,2'-dipyridylamine) were synthesized.In 3 and 4,the ribbon-like chains are connected into a 2D network via the hydrogen-bonding interaction.For 4,the hydrogen-bonding interactions between the crystal water molecules and the terminal O atoms of {MoO₄} tetrahedra exist between the interlayers.They play an important role not only in constructing the 3D architecture,but also in the conformational stability.3.[Zn(dpa)V₂O₆](5) and(6) are two complexes based on infinate 1D {VO₃}_n^n- chains.While the {VO₃}_n^n- chain of 5 exhibits a sinusoidal profile with {Zn(dpa)}²⁺ fragments spanning the adjacent troughs and crests to form a 1D ribbon-like structure.The {VO₃}_n^n- chains of 6 are bridged through {Zn(dpa)}²⁺ fragments to form 2D layers and exhibit single left and right {VO₃}_n^n-helicates in adjacent oxide layers alternately.Their structural characterizations demonstrate the conformational and coordinative diversity of {VO₃}_n^n- chains.4.Complexes[Zn(dpa)V₃O_8.5](7) and[Zn(bpy)Mo₃O₁₀](8) exhibit 2D Structures and they both contain ladder-like clusters in the anions.Complex 7 is based on infinite 2D {V₃O_8.5}^2- layers which consist of ladder-like chains of edge sharing {VO₅} square pyramids bridged through {V₂O₇} fragments.And complex 8 is based on infinite 1D {Mo₃O₁₀}^2- chains that consist of ladder-like chains of edge sharing {VO₅} and {VO₆} polyhedra corner-shared with {VO₄} tetrehedra on the two sides.The Zn centers possess hexahedral and octahedral geometries respectively.