Hydrothermal Chemistry of Oxomolybdenum-1,4-Carboxyphenylphosphonates in the Presence of M(II)-Organonitrogen Building Blocks (M(II) = Co, Ni, and Cu).

Hydrothermal methods were used to prepare a series of materials of the M(II)-L′/MoxOy/H2O3PC6H4CO2H family, where M(II) = Co, Ni, or Cu and L′ = 2,2′-bipyridine (bpy), o-phenanthroline (phen), or 2,2′:6,2′′-terpyridine (terpy). The common {Mo5O15(O3PR)2}4− cluster provided a building block for the one-dimensional (1D) structure of [{Cu(bpy)(H2O)}3{O2CC6H4PO3}2Mo5O15]·4.5H2O (1·4.5H2O). While the pentamolybdate cluster was observed for [Co(terpy)2][Mo5O14(OH){HO2CC6H4PO3}2]·5.25H2O (5·5.25H2O) and [Ni(phen)2(H2O)2][Ni(phen)2Mo5O15{HO2CC6H4PO3}2]·2H2O (6·2H2O), the clusters are present as discrete molecular anions. In contrast, the 1D structure of [Cu(bpy){O3PC6H4CO2H}Mo2O6] (2) exhibits a {Mo2O6}n2n+ chain, decorated with phosphonate and {Cu(phen)}2+ groups. The three-dimensional (3D) structure of [{Cu(phen)}2Mo2O5{O3PC6H4CO2}2]·H2O (3·H2O) is constructed from {Mo2O5}2+ binuclear units, linked into chains through bridging {Cu(phen)}2+ groups; the chains are in turn connected through the dipodal carboxyphenylphosphonate ligands to produce the overall 3D connectivity. Fluoride incorporation in [Cu(bpy){O3PC6H4CO2}MoO2F] (4) results in mononuclear {MoO5F} octahedra linked through {Cu(bpy)}2+ units and the organophosphonate ligand into a chain. The molecular structure of the second polyoxofluoromolybdate species [Co(bpy)3]2[Mo12F4O34(H2O)4{O3PC6H4CO2H}2]·4H2O (7·4H2O) consists of discrete {Co(bpy)3}2+ cations and [Mo12F4O34(H2O)4{O3PC6H4CO2H}2]4− anionic clusters. The unique dodecamolybdate unit of 7 consists of two {Mo6F2O17(H2O)2(O3PR)2}2− subunits fused through two bridging oxo-groups.