POLYOXOMETALATE DERIVATIVES WITH MULTIPLE ORGANIC GROUPS .2. SYNTHESIS AND STRUCTURES OF TRIS(ORGANOTIN) ALPHA,BETA-KEGGIN TUNGSTOSILICATES

Eight tris(organotin)-substituted Keggin tungstosilicate heteropolyani ons have been synthesized and characterized by elemental analysis, inf rared and Mossbauer spectroscopy, multinuclear NMR, and X-ray crystall ography. The new anions contain alpha- or beta-SiW9O3410- moieties and are of two structural types, [(RSn)(3)(SiW9O37)](7-) (R, isomer: Ph, alpha-, 1; n-Bu, alpha-, 2; Ph, beta-, 3; n-Bu, beta-, 4) and [(RSnOH) (3)(SiW9O34)(2)](14-) (Ph, alpha-, 5; n-Bu, alpha-, 6; Ph, beta-, 7; n -Bu, beta-, 8). Crystals of Cs4H3[(PhSn)(3)(SiW9O37)]. 8H(2)O (anion 3 ) are monoclinic, space group C2/c, with lattice constants a = 48.91(2 ) Angstrom, b = 12.111(3) Angstrom, c = 20.334(9) Angstrom, beta = 102 .30 degrees, and Z = 8. The anion has nominal C-3v symmetry and has a structure with three comer-shared WO6 octahedra of the beta-Keggin ani on replaced by three PhSnO(5) groups. Crystals of Cs9H5[(BuSnOH)(3)(Si W9O34)(2)]. 36H(2)O (anion 6) are tetragonal, space group P (4) over b ar 2(1)m, with lattice constants a = b = 29.005(4) Angstrom, c 13.412( 4) Angstrom, and Z = 4. The anion has the anticipated D-3h symmetry an d contains three BuSnOH groups sandwiched between A,alpha-SiW9O3410- a nions.