Trilacunary A-beta-Keggin tungstogermanates and -silicates functionalized with phenyltin(IV) electrophiles

摘要

The first organic derivative of a beta-Keggin tungstogermanate, the monomeric Keggin anion [{(C6H5)Sn(OH)}(3)(A-beta-GeW9O34)](4-) (1), was the only species isolated from the reaction of (C6H5)SnCl3 with Na-10[A-beta-GeW9O34] in water, whereas the Si-analogue [{(C6H5)Sn(OH)}(3)(A-beta-SiW9O34)](4-) (2) and two dimeric tungstosilicates, the unprecedented species [{(C6H5)Sn(A-beta-H3SiW9Sn2O37)}(2)O-2](8-) (3) and the known sandwich-type polyanion [{(C6H5)Sn(OH)}(3)(A-beta-H3SiW9O34)(2)](8-) (4), were isolated starting from [A-beta-SiW9O34](10-). The novel polyanion 3 can be described as the product of a double Sn-C hydrolysis followed by condensation of two subunits of 2 through double Sn-O-Sn bridge formation. Solid-state characterization has been carried out by infrared spectroscopy, thermogravimetry and single-crystal X-ray diffraction, representing the first structural analysis for 4. A full solution multinuclear NMR (H-1, C-13, Sn-117, and W-183) and solid-state Sn-117 CP-MAS NMR study enabled full characterization of 1. A weak 1-dimensional polyanion association through (Sn) O-H center dot center dot center dot O-t hydrogen contacts involving one of the protonated bridging O atoms of the (C6H5)(3)Sn3O12 corner-shared triad is observed for 1 by X-ray diffraction, resulting in a local C-s pseudosymmetry for the Sn centers detected by solid-state Sn-117 NMR spectroscopy.