Two hexa-TM-containing (TM = Co2+ and Ni2+) {P2W12}-based trimeric tungstophosphates

• Published in: Dalton transactions : an international journal of inorganic chemistry 2010-01, Vol.39 (16), p.3884-3889
• Main Authors: Yao, Shuang, Zhang, Zhiming, Li, Yangguang, Wang, Enbo
• Format: Article
• Language: English
• Subjects: Cobalt - chemistry; Crystallography, X-Ray; Molecular Conformation; Nickel - chemistry; Phosphates - chemistry; Polymers - chemistry; Transition Elements; Tungsten - chemistry
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/b921261b

Reactions of hexavacant polyoxotungstates [H(2)P(2)W(12)O(48)](12-) ({P(2)W(12)}) with transition-metal (TM), and alkali-metal ions lead to the isolation of two hexa-TM-containing polyoxotungstates Na(15)[Na(3) subset {M(H(2)O)(4)}(6){WO(H(2)O)}(3)(P(2)W(12)O(48))(3)].xH(2)O (M = Co(2+), x = 109 for 1; M = Ni(2+), x = 110 for 2). Single-crystal X-ray diffraction analysis revealed that compounds 1 and 2 both crystallized in the orthorhombic system, space group Cmcm, with lattice constants a = 21.353(3) A, b = 32.114(3) A, c = 33.848(4) A, for 1; a = 21.643(6) A, b = 31.870(6) A, c = 33.861(7) A for 2. Polyoxoanions [Na(3) subset {M(H(2)O)(4)}(6){WO(H(2)O)}(3)(P(2)W(12)O(48))(3)](15-) in 1 and 2 exhibit a crown-type structure composed of a [{WO(H(2)O)}(3)(P(2)W(12)O(48))(3)](18-) (abbreviated as {P(6)W(39)}) shell encapsulating six TM ions and three Na(+) cations. Polyoxoanions 1 and 2 represent the first hexa-TM-containing {P(2)W(12)}-based trimeric POMs, which offer new examples with the potentially aqua-ligand-induced capability of "trapping" metal ions in the {P(6)W(39)} shell. Electrocatalytic studies show that compounds 1 and 2 display electrocatalytic activity to reduce nitrite.