Transition metal-induced self-assembly of small molybdenum clusters

Abstract

The first-row transition metals (TMs) are applied to induce the assembly of small molybdenum clusters (SMCs) in the molybdenum/TM/phosphate system, and eight SMC-based compounds are synthesized: [(V₂O₂)(H₂PMo₈V₄O₄₀)]·2(en)·12H₂O (1), [CrMo₆O₁₈(OH)₆]·1.5(H₂en)·5H₂O (2), [MnMo₁₂O₂₄(OH)₆(HPO₄)₂(PO₄)₆]·7(H₂en)·6H₂O (3), {[Co(H₂O)]₂[CoMo₁₂O₂₄(OH)₆(H₂PO₄)₂(PO₄)₆]}·4(H₂en)·4H₂O (4), [Ni₅(H₂O)₂₂(Mo₂O₄)₈(HPO₄)₂₀(PO₄)₆]·32H₂O (5), Cu₂(en)₄(Mo₈O₂₆) (6), [Cu(en)₂Mo₅O₁₅(HPO₄)₂]·(H₂en)·2H₂O (7) and {Zn₂[Na(H₂O)₂][NaMo₁₂O₂₄(OH)₆(H₂PO₄)₆(PO₄)₂]}·5(en)·11H₂O (8) (en = ethylenediamine). Six kinds of SMCs as molecular building blocks have been observed within these eight compounds, namely, Mo₂V, Mo₄, Mo₅, Mo₆¹, Mo₆² and Mo₈. In present reaction system, these TMs not only induce the assembly of SMCs, but also regulate the dimensionality of these compounds, ranging from discrete 0D to infinite 1D, 2D and 3D frameworks. Moreover, the electrochemical properties of compounds 1–8 are also investigated.