From Sn(II) to Sn(IV): Enhancing Lewis Acidity Via Oxidation.

We demonstrate the increased Lewis acidity on going from Sn(II) to Sn(IV) by oxidizing Tp Me2 SnOTf (OTf = SO 3 CF 3 ) to Tp Me2 SnF(OTf) 2 . Replacement of the fluoride ion in Tp Me2 SnF(OTf) 2 by a triflate, resulting in Tp Me2 Sn(OTf) 3 further enhances the Lewis acidity at tin. 119 Sn NMR spectroscopy, modified Gutmann-Beckett test, computational analysis, and catalytic phosphine oxide deoxygenation support the claims.