Trimeric, cyclic dimethyltin-containing tungstophosphate [{(Sn(CH3)2)(Sn(CH3)2O)(A-PW9O34)}3]21

The trimeric, cyclic dimethyltin-containing tungstophophate [{(Sn(CH3)(2))(Sn(CH3)(2)O)(A-PW9O34)}(3)](21) (1) has been synthesized in aqueous acidic medium and characterized by IR, elemental analysis, electrochemistry, and FT-ICR MS. Single-crystal X-ray analysis was carried out on Cs12Na9[{(Sn(CH3)(2))(Sn(CH3)(2)O)(A-PW9O34)}(3)]center dot 20H(2)O (1a), which crystallizes in the trigonal system, space group R3, with a = b = 29.7445(7) angstrom, c = 15.5915(7) angstrom and Z = 3. Polyanion 1 is composed of three trilacunary (A-PW9O34) Keggin fragments that are linked on one side via three isolated dimethyltin groups and on the other side by a (Sn-3(CH3)(6)O-3) unit and three cesium ions, resulting in a cyclic assembly with C (3v) symmetry. The discrete molecular, hybrid organic-inorganic 1 was synthesized by reaction of (CH3)(2)SnCl2 with Na-9[A-PW9O34] in 0.5 M sodium acetate buffer (pH 4.8). Comparison of several characteristics of the cyclic voltammograms of 1 and (A-PW9O34)(9), including the potential location of their reduction peaks, the difference in their current intensities and their qualitative relative electron transfer speeds, supports the conclusion that the solid-state structure of 1 is retained in solution. The presence of (PW9O34)-based species in solutions of 1 was also confirmed by FT-ICR mass spectrometry.