Assembly of niobium-phosphate cluster and in situ transition-metal-containing derivatives

Abstract

A novel phosphorus incorporated peroxopolyoxoniobate (CN₃H₆)₆H₄[P₄Nb₆(O₂)₆O₂₄]·4H₂O (1) has been successfully synthesized and characterized. Compound 1 possesses a cluster of [P₄Nb₆(O₂)₆O₂₄]¹⁰⁻ and can be viewed as the fusion of two {P₂Nb₃(O₂)₃O₁₄} subunits by corner-sharing of bridging oxygen atoms. Furthermore, by reacting transition metals with the polyanion [P₄Nb₆(O₂)₆O₂₄]¹⁰⁻ formed in situ, we have discovered a series of transition-metal-containing niobium phosphate cluster derivatives, (CN₃H₆)₄H₄[{Cd(H₂O)₄}{P₄Nb₆(O₂)₆O₂₄}]·7H₂O (2), Cs₃H₃{[M(H₂O)_4.5]₂[P₄Nb₆(O₂)₆O₂₄]}·5H₂O [M = Co (3), Ni (4), Zn (5)] and Cs₃H₃[{Cd(H₂O)₄}₂{P₄Nb₆(O₂)₆O₂₄}]·12H₂O (6). Compounds 2–6 are based on the {P₄Nb₆(O₂)₆O₂₄}¹⁰⁻ cluster and 3, 4 and 5 show zero-dimensional constructions whereas 2 and 6 can form 1D chains attributed to the larger radius of Cd²⁺.