Arsenium cations

Electron deficient coordinatively unsaturated thiaarsoli-dinium cations (50) and (51) have also been isolated. These carbenic arsenium cations have been prepared by the combination of the appropriate chlorodithiaarsolidine complex and a Lewis acid such as AICI3 or GaCb that function as a halide abstractor. The reaction can be carried out in CH2CI2 as the solvent (Scheme 2). 

A monomeric arsenium cation with 67t electrons (60) has been isolated by a metal exchange reaction according to equation (37). ... 

The reaction depicted in equation (37) proceeds with the oxidation of germanium from the 2+ to the 4+ state. The metrical parameters in (60) are in agreement with a localized electron distribution within the five-membered ring, which contrasts the view of aromatic 6 r-stabilization that was invoked for the IOjt electrons arsenium cation (49). 

Only one monocyclic derivative of this ring system, the 2-chloro-l,3-diethyl-l,3,2-diazarsinane (261) has been described in the literature, formed by reaction of N,N -diethyl-l,3-diaminopropane with ASCI3. In trifluoromethanesulfonic acid the cyclic arsenium cations (262) are formed (Equation (45)) <92HAC157>. 

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