Structural Retention of Decatungstates upon Photoreduction

The crystal structures of oxidized and photoreduced decatungstates are compared. Three specimens of decatungstate complexes were prepared in mixed solvents of H2O–CH3CN and were characterized by X-ray diffraction. Unit cell parameters are as follows: (C6H16N)4[W10O32]·2CH3CN; DECA Mr=2841.4, monoclinic, P21⁄n, a=14.617(2), b=17.783(3), c=11.755(2) A, β=100.27(2)°, V=3006.5(9) A3, Z=2; (C6H16N)4[H1.5W10O32]·8H2O; RED1 Mr=2905.4, monoclinic, P21⁄n, a=15.902(3), b=12.233(2), c=15.673(4) A, β=93.76(2)°, V=3042(1), A3 Z=2; Na4[H1.8W10O32]·14H2O; RED2 Mr=2696.7, monoclinic, C2⁄m, a=16.123(5), b=12.636(3), c=12.168(4) A, β=117.40(2)°, V=2202(1) A3, Z=2; There is no obvious change in the anion frame among the three decatungstate complexes. Photoreduced decatungstates may coordinate protons which neutralize excess charge injected into anions. It is concluded that the structure of W10O32 is not largely altered up to two-electron reduction.