Metal oxide-organic frameworks (MOOFs), a new series of coordination hybrids constructed from molybdenum(VI) oxide and bitopic 1,2,4-triazole linkers.

A series of molybdenum(VI) oxide-organic solids were prepared by hydrothermal reactions employing N-donor tectons, which combine two 1,2,4-triazol-4-yl sites separated by representative aliphatic spacers (ethylene, tr(2)eth; 1,3-propylene, tr(2)pr; trans-1,4-cyclohexanediyl, tr(2)cy; diamondoid 1,3-adamantanediyl, tr(2)ad; 1,6- and 4,9-diamantanediyls, 1,6-tr(2)dia and 4,9-tr(2)dia) and heterofunctional 5-[4-(1,2,4-triazol-4-yl)phenyl]tetrazole (trtz). In all the compounds the 1,2,4-triazol-4-yl group acts as a short-distance N(1),N(2)-bridge between two Mo ions (Mo-N 2.36-2.50 A). The 3D framework structure is based upon pseudo-4(1) helices ([Mo(4)O(12)(tr(2)eth)(2)] 1, [Mo(2)O(6)(tr(2)cy)] 3) or sinusoidal chains ([Mo(2)O(6)(tr(2)pr)] 2, [Mo(2)O(6)(tr(2)ad)].6H(2)O 4, [Mo(2)O(6)(4,9-tr(2)dia)].0.5H(2)O 5) of vertex-sharing MoO(4)N(2) octahedra, while the bitopic organic ligands manifest a dual role as connectors for two adjacent octahedra and as links between separate 1D inorganic subtopologies. For linear, lengthy tectons tr(2)cy and 4,9-tr(2)dia two identical frameworks interpenetrate. In [MoO(3)(trtz)] 7, the 4(1) helices aggregate into 3D tetragonal framework (five-fold interpenetrated) by hydrogen bonding between the tetrazole groups. The 2D structure of [Mo(4)O(12)(1,6-tr(2)dia)].2H(2)O 6 is influenced by the very bulky aliphatic portion of the ligands, which connect chains of edge-shared octahedra MoO(5)N (Mo-N 2.346(2), 2.456(2) A).