Mixed valence tungsten oxides with a tunnel structure, P 4W 4 nO 12 n+8 : A nonintegral member P 4W 10O 38 ( n = 2.5)
The mixed-valence oxide P 4W 10O 38, which can be considered as the nonintegral member n = 2.5 of the series P 4W 4 nO 12 n+8 , crystallizes in the monoclinic system with unit-cell dimensions a = 6.5656(25), b = 5.2850(15), c = 20.573(15) Å, β = 96.18(4)°, and space group P2 1. The crystal structure was solved by conventional Patterson and Fourier techniques using 2339 counter-measured reflections that obeyed the condition I > 3 σ( I) and refined to an R factor of 0.074 ( Rw = 0.077). Basically, the framework of the structure built up from ReO 3-type slabs connected through PO 4 tetrahedra looks like that of P 4W 8O 32 previously described. Unlike P 4W 8O 32, two successive ReO 3-type slabs have a different width corresponding to two and three WO 6 octahedra so that the structure can be considered as an intergrowth of the integral members n = 2 and n = 3 of the series P 4W 4 nO 12 n+8 .