The Arene‐Stabilized η 5 ‐Pentamethylcyclopentadienyl Arsenic Dication [(η 5 ‐Cp*)As(toluene)] 2+

Double chloride abstraction of Cp*AsCl 2 gives the dicationic arsenic species [(η 5 ‐Cp*)As(tol)][B(C 6 F 5 ) 4 ] 2 ( 2 ) (tol=toluene). This species is shown to exhibit Lewis super acidity by the Gutmann–Beckett test and by fluoride abstraction from [NBu 4 ][SbF 6 ]. Species 2 participates in the FLP activation of THF affording [(η 2 ‐Cp*)AsO(CH 2 ) 4 (THF)][B(C 6 F 5 ) 4 ] 2 ( 5 ). The reaction of 2 with PMe 3 or dppe generates [(Me 3 P) 2 As][B(C 6 F 5 ) 4 ] ( 6 ) and [(σ‐Cp*)PMe 3 ][B(C 6 F 5 ) 4 ] ( 7 ), or [(dppe)As][B(C 6 F 5 ) 4 ] ( 8 ) and [(dppe)(σ‐Cp*) 2 ][B(C 6 F 5 ) 4 ] 2 ( 9 ), respectively, through a facile cleavage of C−As bonds, thus showcasing unusual reactivity of this unique As‐containing compound.