Assembly of various reduced molybdophosphate-based cadmium complexes by controllable in situ ligand transformation

Two novel reduced molybdophosphate-based cadmium complexes, [Cd(MoO2)(12)(PO4)(2)(HPO4)(2)(H2PO4)(4)(OH)(6)][Cd(H2O)(2)] center dot(H(2)bpp)(2)center dot bpp center dot 7H(2)O (1); [Cd(MoO2)(12)(PO4)(4)(HPO4)(2)(H2PO4)(2)(OH)(6)]{Cd(H2O)(2)[K(H2O)(2)](2)}center dot(H(4)tpc)(H(2)bpp)center dot 11H(2)O (2) (bpp = 1,3-bis-(4-pyridyl)propane, tpc = a, a-1,4-dihydroxye,e,e,e-1,2,4,5-tetra-(4-pyridyl)cyclohexane) have been synthesized by controlling in situ bpp transformation and characterized by IR and single crystal X-ray diffraction. Both compounds 1 and 2 are based on the [P4Mo6O28(OH)(3)](9) ([P4Mo6]) polyoxometalate units, which are further connected into sandwich-type [Cd(P4Mo6)(2)] dimers by cadmium ions. In compound 1, [Cd(P4Mo6)(2)] dimers are linked by cadmium ions to form one dimensional (1D) inorganic chains, which are extended into 2D supramolecular network by bpp/H(2)bpp through hydrogen bonding interactions. In 2, bpp molecules partially in situ transformed to tpc at the presence of Fe3+ ion and pH 4.5, and the [Cd(P4Mo6)(2)] dimers are linked by trinuclear {K2Cd(H2O)(6)} fragments to form 1D inorganic chains. Finally, the 1D chains are connected by H(2)bpp and in situ generated H(4)tpc molecules to construct a 3D supramolecular architecture through hydrogen bonding interactions. The Fe3+ ions and pH play important roles in the in situ ligand transformation, which show great effect on the assembly and structures of the title compounds. The electrochemical properties of compound 2 have been investigated. (C) 2014 Elsevier B.V. All rights reserved.