Abstract
In contrast to the well-known phosphorus(III) donor systems, comparatively few cases are known in which P(III) displays acceptor properties, cf., e.g.1,2. Adducts of the type X3P ← Nu (Nu = nucleophilel are of special Interest as models of nucleophilic substitution reactions at P(III), and have been isolated, in some cases3. Compound 1. reported in 1966 4, probably constitutes the first case of an in-tramolecular complex involving P(III) as acceptor.