(Dimethylaminomethyliden)-phenylarsan, ein acyclisches Alkylidenarsan (Acyl- und Alkylidenarsane ; 5)

Abstract

In the absence of a catalyst phenyl-bis(trimethylsilyl)arsine reacts only very slowly with excess dimethylformamide (4) to give (dimethylaminomethylidene)-phenylarsine and hexamethyldisiloxane. In the presence of small amounts of solid sodium hydroxide, however, the reaction is already finished after four days at + 20° C. Similarly, lithium phenyltrimethylsilylarsenide · DME, which can easily be obtained from 1 a and methyllithium in 1,2·dimethoxyethane (DME), and dimethylformamide also form the alkylidenearsine (8a) and lithium trimethylsilanoIate. The NMR spectra of 3a show the rotation of the dimethylamino group to be hindered with a barrier of about 63 kJ · mol-1.