Synthesis, Crystal Structure, And Characterization Of Transition-Metal Complexes Based On Oxomolybdate Building Blocks

There has been a great interest in assembly of transition-metal complex based on polyoxometalate blocks owing to not only containing a abundant structural chemistry, but also combining properties of polyoxometalates and complexes. On the basis of molecular design and assembly, eight novel complexes based on oxomolybdate building blocks, which are bridged by transition metal ions or transition metal complexes, have been successfully synthesized in aqueous (or mixed solvent).(1) NH₄[Ag₂(H₂O)₂{Cr(OH)₆Mo₆O₁8}]·2H₂O(2) (NH₄)₃[Ag{Cr(OH)₆Mo₆O₁8}][Ag₂(H₂O)₂{Cr(OH)₆Mo₆O₁8}]·10H₂O(3) (NH₄)₃[Ag{Fe(OH)₆Mo₆O₁8}][Ag₂(H₂O)₂{Fe(OH)₆Mo₆O₁8}]·11H₂O(4) Cu(H₂O)(Hdpa)MoO₄·H₂OThey were determined structurally by single-crystal x-ray diffraction and characterized by elemental analysis, IR spectroscopy and thermogravimetric analysis.Complexes 1-3 have been assembled by usingβ-Anderson clusters as building blocks and silver(I) ions as bridging ligand to yield 2D network. In 1, four adjacent Anderson anions were linked through two {AgO6} octahedra via terminal and bridge oxygen atoms, and the two {AgO6} octahedra are edge-shared to from the binuclear unit. The adjacent sheets exhibit an interesting three-dimensional supramolecular architecture via hydrogen bonding interactions. However, in 2 and 3, there are two different linked modes. One is four adjacent Anderson anions were linked through one {AgO6} octahedron via terminal oxygen atoms along the b-axis, and the other is that four adjacent anderson anions were linked through two {AgO6} octahedra via terminal oxygen atoms along the b-axis, and the two {AgO6} octahedra are edge-shared. The two different connectivities are arranged alternately along the c-axis to form a 2D network.A novel 1D zigzag chain-like complex 4 has been synthesized. It is built up from the bidentate {MoO4}2? building blocks bridged through the {Cu(H2O) (Hdpa)}2+ units. The chains extend along the c-axis and are arranged alternately with two opposite orientations along the b-axis. The adjacent chains are stably packed together and exhibit an interesting three-dimensional supramolecular architecture via hydrogen bonding interactions. The metal center possesses a square pyramids.In addition, three simple transition-metal complexes, [CoCl₂(C₂4H₂0N₂)₂] (5), [ZnCl₂(C₂4H₂0N₂)₂] (6) and [Ni(Hdpa)₂(dca)₂] (7), have been synthesized in a mixture of methanol and water. In 5 and 6, two nitrogen atoms and two chlorine atoms complete the metal center MII (M=Co, Zn) coordination, showing a distorted tetrahedral geometry, respectively. Because of the large volume of the 2-[N-(triphenylmethy) imino] pyridyl ligand, the formation of a four-coordinate complex is more possible rather than six-coordinate one. In 7, six nitrogen atoms complete the metal center Ni coordination, showing an octahedral geometry.