Ligand Influences on the Structures of Molybdenum Oxide Networks

• Published in: Inorganic chemistry Vol. 39; no. 19; pp. 4311 - 4317
• Main Authors: Hagrman, Pamela J, LaDuca, Robert L, Koo, H.-J, Rarig, Randy, Haushalter, Robert C, Whangbo, Myung-Hwan, Zubieta, Jon
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 18.09.2000
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic000496l

The influence of organonitrogen ligands on the network structure of molybdenum oxides was examined by preparing three new molybdenum oxide phases [MoO3(4,4‘-bpy)0.5] (MOXI-8), [H x MoO3(4,4‘-bpy)0.5] (MOXI-9), and [MoO3(triazole)0.5] (MOXI-32). The structure of [MoO3(4,4‘-bpy)0.5] consists of layers of corner-sharing MoO5N octahedra, buttressed by bridging 4,4‘-bipyridyl ligands into a three-dimensional covalently bonded organic−inorganic composite material. Partial reduction of [MoO3(4,4‘-bpy)0.5] yields the mixed-valence material [H x MoO3(4,4‘-bpy)0.5] (x ≈ 0.5). The most apparent structural change upon reduction is found in the Mo−ligand bond lengths of the MoO5N octahedra, which exhibit the usual (2 + 2 + 2) pattern in [MoO3(4,4‘-bpy)0.5] and a more regular (5 + 1) pattern in [H x MoO3(4,4‘-bpy)0.5]. Substitution of triazole for 4,4‘-bipyridine yields [MoO3(triazole)0.5], which retains the layer motif of corner-sharing MoO5N octahedra but with distinct sinusoidal ruffling in contrast to planar layers of [MoO3(4,4‘-bpy)0.5] and [H x MoO3(4,4‘-bpy)0.5]. The folding reflects the ligand constraints imposed by the triazole ligand that bridges adjacent Mo sites within a layer. MOXI-8, C5H4NMoO3:  monoclinic P21/c, a = 7.5727(6) Å, b = 7.3675(7) Å, c = 22.433(3) Å, β = 90.396(8)°, Z = 8. MOXI-9, C5H4.5NMoO3:  monoclinic I2/m, a = 5.2644(4) Å, b = 5.2642(4) Å, c = 22.730(2) Å, β = 90.035(1)°, Z = 4. MOXI-32, C2H3N3Mo2O6:  orthorhombic Pbcm, a = 3.9289(5) Å, b = 13.850(2) Å, c = 13.366(2) Å, Z = 4.