Phenyltin-Substituted 9-Tungstogermanate and Comparison with Its Tungstosilicate Analogue

Reaction of (C₆H₅)SnCl₃ with Na₁₀[A-α-GeW₉O₃₄] in water results in the monomeric, trisubstituted Keggin species [{(C₆H₅)Sn(OH)}₃(A-α-GeW₉O₃₄)]⁴⁻ (1), constituting the first organotin derivative of a trilacunary Keggin tungstogermanate. Polyanion 1 could be obtained as two different cesium salts depending on the applied isolation strategy: Cs₃Na[{(C₆H₅)Sn(OH)}₃(A-α-GeW₉O₃₄)]·9H₂O (CsNa-1) and Cs₃[{(C₆H₅)Sn(OH)}₃(A-α-HGeW₉O₃₄)]·8H₂O (Cs-H1). The monomeric phenyltin-containing tungstosilicate [{(C₆H₅)Sn(OH)}₃(A-α-SiW₉O₃₄)]⁴⁻ (2) and the dimeric, sandwich-type derivative [{(C₆H₅)Sn(OH)}₃(A-α-H₃SiW₉O₃₄)₂]⁸⁻ (3) have also been isolated as the cesium salts Cs₃Na[{(C₆H₅)Sn(OH)}₃(A-α-SiW₉O₃₄)]·9H₂O (CsNa-2), Cs₄[{(C₆H₅)Sn(OH)}₃(A-α-SiW₉O₃₄)]·13H₂O (Cs-2), and Cs₈[{(C₆H₅)Sn(OH)}₃(A-α-H₃SiW₉O₃₄)₂]·23H₂O (Cs-3), respectively. We have investigated in detail the similarities and differences in the reactivity of (C₆H₅)Sn³⁺ with [A-α-GeW₉O₃₄]¹⁰⁻ vs [A-α-SiW₉O₃₄]¹⁰⁻. All five compounds have been characterized in the solid state by means of elemental analysis, infrared spectroscopy, thermogravimetry, and single-crystal X-ray diffraction, representing the first structural analysis for polyanions 1−3. A full solution characterization of 1 by multinuclear NMR spectroscopy (¹H, ¹³C, ¹¹⁹Sn, and ¹⁸³W) has also been performed. The monomeric polyanions 1 and 2 are closely associated in the solid state through (Sn)O−H···O_t (O_t: terminal oxygen atom) hydrogen bonds reinforced by weak C−H···O_t contacts to form 2-dimensional (CsNa-1 and CsNa-2) or 1-dimensional (Cs-H1) arrangements, and also dimeric entities (Cs-2) depending on the network of intermolecular interactions.