Cationic Functionalisation by Phosphenium Ion Insertion.

Abstract

The reaction of [Cp′′′Ni(η3‐P3)] (1) with in situ generated phosphenium ions [RR′P]+ yields the unprecedented polyphosphorus cations of the type [Cp′′′Ni(η3‐P4R2)][X] (R=Ph (2 a), Mes (2 b), Cy (2 c), 2,2′‐biphen (2 d), Me (2 e); [X]−=[OTf]−, [SbF6]−, [GaCl4]−, [BArF]−, [TEF]−) and [Cp′′′Ni(η3‐P4RCl)][TEF] (R=Ph (2 f), tBu (2 g)). In the reaction of 1 with [Br2P]+, an analogous compound is observed only as an intermediate and the final product is an unexpected dinuclear complex [{Cp′′′Ni}2(μ,η3:η1:η1‐P4Br3)][TEF] (3 a). A similar product [{Cp′′′Ni}2(μ,η3:η1:η1‐P4(2,2′‐biphen)Cl)][GaCl4] (3 b) is obtained, when 2 d[GaCl4] is kept in solution for prolonged times. Although the central structural motif of 2 a–g consists of a “butterfly‐like” folded P4 ring attached to a {Cp′′′Ni} fragment, the structures of 3 a and 3 b exhibit a unique asymmetrically substituted and distorted P4 chain stabilised by two {Cp′′′Ni} fragments. Additional DFT calculations shed light on the reaction pathway for the formation of 2 a–2 g and the bonding situation in 3 a.