Dimerization of mono-ruthenium substituted alpha-Keggin-type tungstosilicate [alpha-SiW11O39RuIII(H2O)](5-) to mu-oxo-bridged dimer in aqueous solution: Synthesis, structure, and redox studies

作者：Sadakane Masahiro^*; Tsukuma Daisuke; Dickman Michael H; Bassil Bassem S; Kortz Ulrich; Capron Mickael; Ueda Wataru

来源：Dalton Transactions, 2007, (26): 2833-2838.

DOI：10.1039/b702813j

We report the dimerization of a mono-ruthenium( III) substituted alpha-Keggin-type tungstosilicate [alpha-SiW11O39RuIII(H2O)](5-) to a mu-oxo-bridged dimer [{alpha-SiW11O39Rum}(2)O] (n-)( m = III, n = 12; m = IV/ III, n = 11; m = IV, n = 10). Single crystal X-ray structure analysis of Rb-10[{alpha-SiW11O39RuIV}(2)O] center dot 9.5H(2)O ( triclinic, P (1) over bar, with a = 12.7650( 6) angstrom, b = 18.9399( 10) angstrom, c = 20.2290( 10) angstrom, alpha = 72.876( 3)degrees, beta = 88.447( 3)degrees, gamma = 80.926( 3)., V = 4614.5( 4) angstrom(3), Z = 2) reveals that two mono-ruthenium substituted tungstosilicate alpha-Keggin units are connected through mu-oxo-bridging Ru-O-Ru bonds. Solution W-183-NMR of [{SiW11O39RuIV}(2)O](10-) resulted in six peaks (- 63, - 92, - 110, - 128, - 132, and - 143 ppm, intensities 2 : 2 : 1 : 2 : 2 : 2) confirming that the mu-oxo bridged dimer structure is maintained in aqueous solution. The dimerization mechanism is presumably initiated by deprotonation of the aqua-ruthenium complex [alpha-SiW11O39RuIII( H2O)](5-) leading to a hydroxy- ruthenium complex [alpha-SiW11O39RuIII(OH)](6-). Dimerization of two hydroxy-ruthenium complexes produces the mu-oxo bridged dimer [{alpha-SiW11O39RuIII}(2)O](12-) and a water molecule. The Ru(III) containing dimer is oxidized by molecular oxygen to produce a mixed valence species [{alpha- SiW11O39RuIV-III}(2)O](11-), and further oxidation results in the Ru( IV) containing [{alpha- SiW11O39RuIV}(2)O](10-).

• 出版日期2007