Synthesis and structures of two novel one-dimensional mixed-valence iron molybdophosphate matrices

Abstract

Two composite solids consisting of one-dimensional mixed-valence iron and molybdenum phosphates with metal complexes, [(C₁₀H₈N₂)₃Fe^II]₃Fe^II₂Fe^III₂Mo^V₂₄(H₂PO₄)₈(HPO₄)₄(PO₄)₄O₄₈(OH)₁₂(H₂O)₄·12H₂O (1) and [(C₁₀H₈N₂)₃Fe^II]₂Fe^IIFe^IIIMo^V₁₂(H₂PO₄)₂(H_2 − xPO₄)(H_1 + xPO₄)(HPO₄)₂(PO₄)₂O₂₄(OH)₆(H₂O)₂ ·9H₂O (x = 0–1) (2), in which the one-dimensional inorganic anions are constructed of alternating [Fe^II(P₈Mo₁₂)] units and Fe^III ions, were synthesized by hydrothermal reaction of MoO₃, H₃PO₄, Fe₂(C₂O₄)₃·5H₂O, 2,2′-bipyridine, H₂C₂O₄ ·2H₂O and H₂O, and characterized by elemental analysis and single-crystal X-ray diffraction. Though the non-hydrogen atomic ratios among Mo, Fe, P, O in the anionic chains are the same, the protonation of the PO₄ groups is different in 1 and 2, with the result that the anionic chains carry different charges and subsequently give rise to different numbers of Fe^II(2,2′-bipyridine)₃ per {Fe^III₂[Fe^II₂(P₁₆Mo^V₂₄)]} unit.