B(C6F5)3‐Catalyzed Selective Chlorination of Hydrosilanes

The chlorination of Si−H bonds often requires stoichiometric amounts of metal salts in conjunction with hazardous reagents, such as tin chlorides, Cl₂, and CCl₄. The catalytic chlorination of silanes often involves the use of expensive transition‐metal catalysts. By a new simple, selective, and highly efficient catalytic metal‐free method for the chlorination of Si−H bonds, mono‐, di‐, and trihydrosilanes were selectively chlorinated in the presence of a catalytic amount of B(C₆F₅)₃ or Et₂O⋅B(C₆F₅)₃ and HCl with the release of H₂ as a by‐product. The hydrides in di‐ and trihydrosilanes could be selectively chlorinated by HCl in a stepwise manner when Et₂O⋅B(C₆F₅)₃ was used as the catalyst. A mechanism is proposed for these catalytic chlorination reactions on the basis of competition experiments and density functional theory (DFT) calculations.     

The Arene‐Stabilized η5‐Pentamethylcyclopentadienyl Arsenic Dication [(η5‐Cp*)As(toluene)]2+

Double chloride abstraction of Cp*AsCl₂ gives the dicationic arsenic species [(η⁵‐Cp*)As(tol)][B(C₆F₅)₄]₂ ( 2 ) (tol=toluene). This species is shown to exhibit Lewis super acidity by the Gutmann–Beckett test and by fluoride abstraction from [NBu₄][SbF₆]. Species 2 participates in the FLP activation of THF affording [(η²‐Cp*)AsO(CH₂)₄(THF)][B(C₆F₅)₄]₂ ( 5 ). The reaction of 2 with PMe₃ or dppe generates [(Me₃P)₂As][B(C₆F₅)₄] ( 6 ) and [(σ‐Cp*)PMe₃][B(C₆F₅)₄] ( 7 ), or [(dppe)As][B(C₆F₅)₄] ( 8 ) and [(dppe)(σ‐Cp*)₂][B(C₆F₅)₄]₂ ( 9 ), respectively, through a facile cleavage of C?As bonds, thus showcasing unusual reactivity of this unique As‐containing compound.