Three 1-D molybdenum(V) phosphates with copper/nickel coordination cations

Abstract

Three 1-D reduced molybdenum(V) phosphates, [Ni(OH)2][Na2(H2O)3]2{Ni[(MoO2)6(OH)3(HPO4)3(PO4)]2} · 2C6H14N2 · 2H3O · 5H2O (1), [Ni(H2O)2][K(H2O)5]2{Ni[(MoO2)6(OH)3(HPO4)3(PO4)]2} · 2C6H14N2 · 2H3O · 4H2O (2), and [Cu(H2O)2][Na(H2O)5]2{Cu[(MoO2)6(OH)3(HPO4)3(PO4)]2} · 2C6H14N2 · 2H3O · 4H2O (3), have been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. The crystallographic analysis reveals that 1 is based on {Ni[Mo6O12(OH)3(HPO4)3(PO4)]2} clusters connected through {[Ni(OH)2][Na2(H2O)3]2} pentanuclear mixed-metal cluster units to yield unusual 1-D chains along the c-axis, which further form 3-D supramolecular networks via hydrogen-bonding. Compounds 2 and 3 are heterogeneous isostructural compounds. Both are built from M[Mo6P4]2 (M = Ni or Cu) blocks as the structural motif combined with [MO4(H2O)2] (M = Ni or Cu) octahedra to form 1-D chains, where M[Mo6P4]2 (M = Ni or Cu) is bonded by [M′(H2O)5] (M′ = K or Na). Furthermore, bulk carbon paste electrode modified with 1 (1-CPE) displays good electrocatalytic activity toward reduction of nitrite or bromate.