Reactivity\nStudy of the Bis(phosphine)-Stabilized\nAntimony(I) Cation

The 5,6-Bis(diisopropylphosphino)acenaphthene <b>L</b>-stabilized\nSb(I) cationic compound [LSb][OTf] (OTf = CF<sub>3</sub>SO<sub>3</sub>) <b>1</b> possessing two lone pairs of electrons on the Sb(I)\ncenter showed nucleophilic behavior toward methyl trifluoromethanesulfonate\nforming the oxidized product [LSbMe][OTf]<sub>2</sub> <b>2</b> (OTf = CF<sub>3</sub>SO<sub>3</sub>). Reaction of compound <b>1</b> with Lewis acids such as GaCl<sub>3</sub> and AlBr<sub>3</sub> led to changes in the counteranions only giving products [LSb][GaCl<sub>4</sub>] <b>3</b> and [LSb][SbBr<sub>4</sub>] <b>4</b>, respectively. A metathesis reaction was observed when compound <b>1</b> was reacted with PI<sub>3</sub>. The Sb(I) cation in <b>1</b> underwent the metathesis reaction with the P(I) cation,\nforming the more stable product [LP][OTf] <b>5</b>. The Sb(I)\ncenter in <b>1</b> was completely oxidized to Sb(V) by reacting\nwith two equivalents of <i>o</i>-chloranil to give the Bis(phosphine)-stabilized\nBis(perchloro catecholato)stibonium cation [L(O<sub>2</sub>C<sub>6</sub>Cl<sub>4</sub>)<sub>2</sub>Sb][OTf] <b>6</b>. Both compounds <b>1</b> and <b>6</b> were employed as proof-of-concept Lewis\nacid catalysts for the hydrosilylation of <i>p</i>-methyl\nbenzaldehyde. All the compounds were characterized using single-crystal\nX-ray diffraction analysis, multinuclear nuclear magnetic resonance\nspectroscopy, mass spectrometry, and absorbance spectroscopy. Density\nfunctional theory calculations were performed on the relevant compounds.