Inorganic Chemistry, Vol.45, No.11, 4313-4315, 2006
Synthesis, characterization, and crystal structures of two novel high-nuclear nickel-substituted dimeric polyoxometalates
Two novel high-nuclear Ni-substituted polyoxometalates Na9K[Ni-7( OH)(4)(H2O)(CO3)(2)(HCO3)(A-alpha-SiW9O34)(beta-SiW10O37)] center dot 5H(3)O center dot 18H(2)O ( 1) and K6Na4[{N(i)6(H2O)(4)(mu(2)-H2O)(4)(mu(3)-OH)(2)}(x-SiW9O34)(2)] center dot 17.5H(2)O (2) have been obtained by reaction of K-8[gamma-SiW10O36] with NiCl2 center dot 2H(2)O in basic conditions. Compounds 1 and 2 all represent the first polyoxometalates substituted by seven and six Ni centers, respectively. Also, compound 1 exhibits a novel asymmetric dimeric structure, composed of [A-alpha-SiW9O34](10-) and [beta-SiW10O37](10)- units linked by a Ni-7 cluster and three carbonates, which exhibit tri- and bidentate coordination modes in 1.