A Nucleophilic Tin(II) Cation Salt

We show that one of the tris(carbene)borate (TCB) ligands, namely [PhB(tBuIm)3]- ([PhB(tBuIm)3]- = phenyltris(3-tert-butylimidazol-2-ylidene)borato), is capable of stabilizing an unprecedented nucleophilic Sn(II) cation salt. Unlike known Sn(II) cations, the strong electron-donating ability of [PhB(tBuIm)3]- makes the cationic tin atom electron-rich, σ-donating yet slightly π-accepting, which allows for the ensuing facile oxidation with o-chloranil and S8 as well as coordination with coinage metals. The former oxidations give rare Sn(IV) cation salts, while the latter reactions produce novel metal complexes. The electronic structures of these species are thoroughly probed by quantum chemical computations. These results unravel an added role for TCB ligands in isolating unprecedented p-block species.