Investigations into the Engineering of Inorganic/Organic Solids: Hydrothermal Synthesis and Structure Characterization of One-Dimensional Molybdenum Oxide Polymers

Hydrothermal synthesis of molybdenum (VI) oxide polymers has been investigated in the presence of various organic structure-directing units. From strong acidic media, chain- and layer-structured inclusion compounds based on molybdenum oxide, MoO-2 and MoO-3 were obtained. The most favorable structure-directing units are 1,2-ethylenediamine (1,2-EDA) for MoO-2, and piperizine (PIP) for MoO-3. Zn 2+ -piperizine leads to successful synthesis of both MoO-2 and MoO-3, however, Zn 2+ no longer remains in final products. Crystal data: MoO-2, (Mo 6 O 20 ) 4− · 2(1,2-C 2 N 2 H 10 ) 2+ , monoclinic space group P2 1 /n (No. 14), a =8.092(2) , b =14.485(3) , c =8.922(2) , β=98.20(3)°, Z=2 and MoO-3, (Mo 5 O 16 ) 2− · (C 4 N 2 H 12 ) 2+ , monoclinic space group C2/c (No. 15), a =23.324(4) , b =5.6070(10) , c =14.380(3) , β =115.980(10)°, Z=2. The structure of MoO-2 is built up from infinite puckered chains of (Mo 6 O 20 ) units stretching along bia-axis. Protonated 1,2-EDA cations occupy the interstrand regions. In MoO-3, the (Mo 5 O 16 ) sheets run parallel to bibc-plane and stacked along bia-axis in biABAB… order with piperazinium ions sandwiched in the interlamellar space. In both compounds, molybdenum atoms are linked up by sharing corners and edges. They locate in the center of distorted octahedra with 1-, 2- and 3-coordinated oxygen ligands. The syntheses of MoO-2 and MoO-3 reflect the power of the hydrothermal technique for assembly of inorganic/organic compounds. It highlights an excellent approach towards material engineering.