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

Abstract

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.

Synthesis and Structures of s- and p-Block Metal Complexes Containing Sterically Demanding Pentaarylcyclopentadienyl Substituents

“…The As1–C2 and As1–C5 bond distances in the Cp*AsX 2 complexes are slightly shorter compared to those in 17 ; hence the bonding nature of the Cp* substituents was described as “pseudo η 3 ”. Very recently, the solid-state structures of Cp*-substituted arsenic mono- [(η 2 -Cp*)­AsCl]­[B­(C 6 F 5 ) 4 ] and dication [(η 5 -Cp*)­As­(tol)]­[B­(C 6 F 5 ) 4 ] 2 were reported by Stephan et al, whereas Krossing et al previously reported on [(η 2 -Cp*)­AsCl]­[ClAl­(OC­{CF 3 } 3 ) 3 ] and Jutzi et al structurally characterized the arsenocene cation [(Cp*) 2 ­As] + , respectively. The [(η 5 -Cp*)­As­(tol)] dication represents the only structurally characterized arsenic compound containing an η 5 -coordinated Cp* substituent complexes, to date.…”