The Bis-Phenyltin-Substituted, Lone-Pair-Containing Tungstoarsenate [(C₆H₅Sn)₂As₂W₁₉O₆₇(H₂O)]^8-

The bis-phenyltin-substituted, lone-pair-containing tungstoarsenate [(C6H5Sn)2As2W19O67(H2O)]8- (1) has been synthesized and characterized by multinuclear NMR, IR, and elemental analysis. Single-crystal X-ray analysis was carried out on (NH4)7Na[(C6H5Sn)2As2W19O67(H2O)]·17.5H2O (NH4−1), which crystallizes in the monoclinic system, space group P21/c, with a = 18.3127(17) Å, b = 24.403(2) Å, c = 22.965(2) Å, β = 106.223(2)°, and Z = 4. Polyanion 1 consists of two B-α-(AsIIIW9O33) Keggin moieties linked via a WO(H2O) fragment and two SnC6H5 groups leading to a sandwich-type structure with nominal C2v symmetry. Polyanion 1 is stable in solution as indicated by the expected 6-line pattern (4:4:4:4:2:1) in 183W NMR and the expected 119Sn, 13C, and 1H NMR spectra. Synthesis of 1 was accomplished by reaction of C6H5SnCl3 and K14[As2W19O67(H2O)] in a 2:1 molar ratio in aqueous acidic medium (pH 2). In the solid-state structure of NH4−1, neighboring polyanions are weakly bound via W−O−Na bonds leading to chains which interact with each other via the phenyl rings resulting in a 2-D assembly.