Utilization of a Tris(carbene)borate Ligand for Umpolung Reactivity of a Nucleophilic Tin(II) Cation Salt

Abstract

We show that a tris(carbene)borate (TCB) ligand, namely [PhB( t BuIm) 3 ] − ([PhB( t BuIm) 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-( t BuIm) 3 ] − makes the cationic tin atom electron-rich, σ-donating yet slightly πaccepting, which allows for the ensuing facile oxidation with o-chloranil and S 8 as well as coordination with coinage metals. The former oxidations give the Sn(IV) cation salts, while the latter reactions produce the metal complexes. The electronic structures of these species are thoroughly probed by quantum chemical computations. These results uncover an added role for TCB ligands in isolating unprecedented p-block species.

Activation of the GaI Cation for Bond Activation: from Oxidative Additions into C−Cl and H−P Bonds to Reversible Insertion into P4

“…The surprisingly high stability of the formed Ga−Ga bonds impeded the activation of small molecules such as white phosphorous in a previous study [15] . Umpolung of the reactivity of a Sn II cation by a tris(carbene)borate ligand has also been previously reported by Liu [17] …”

“…[15] Umpolung of the reactivity of a Sn II cation by a tris(carbene)borate ligand has also been previously reported by Liu. [17] Intriguingly, although the reductive elimination of H 2 at Ga III H 2 + was already shown to give a low-valent gallium cation, the oxidative insertion of a monomeric Ga(I) cation into element-element bonds has not yet been reported. Notably, a preliminary study reported the reduction of HÀ P and ClÀ P bonds in [HÀ PPh 3 ] + [Al(OR F ) 4 ] À and ClÀ PPh 2 respectively.…”

Ligand-enforced geometric constraints and associated reactivity in p-block compounds

“…140 Another Sn( ii ) complex supported by a tridentate pincer ligand, 41 , was reported by Liu. 141 This cationic tin center displays unusual nucleophilicity due to the strong donating nature of the ligand which features three carbene donors, enabling coordination complexes with gold and silver. As there are lone pairs in the germanium and tin centres discussed here, the geometry does not experience a significant distortion from that expected by VSEPR theory.…”