Tin-Centered Radical and Cation: Stable and Free

The first stable stannyl radical (tBu2MeSi)3Sn• (1) has been synthesized by the reaction of tBu2MeSiNa with SnCl2−dioxane in diethyl ether. The X-ray crystal structure and electron paramagnetic resonance (EPR) data of this radical show that 1 has a planar geometry, being a π-radical in both the solid and the liquid states. One-electron oxidation of 1 with Ph3C+·B(C6F5)4- in benzene quantitatively produced the corresponding cation (tBu2MeSi)3Sn+·B(C6F5)4- (2), representing the stable free stannylium ion that has been fully characterized by X-ray analysis and NMR data. Being free, 2 features a record downfield shifted resonance for stannylium ions:  +2653 ppm.