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···Ot (Ot: terminal oxygen atom) hydrogen bonds reinforced by weak C−H···Ot 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.