Cationic Functionalisation by Phosphenium Ion Insertion.

The reaction of [Cp'''Ni(η -P )] (1) with in situ generated phosphenium ions [RR'P] yields the unprecedented polyphosphorus cations of the type [Cp'''Ni(η -P R )][X] (R=Ph (2 a), Mes (2 b), Cy (2 c), 2,2'-biphen (2 d), Me (2 e); [X] =[OTf] , [SbF ] , [GaCl ] , [BAr ] , [TEF] ) and [Cp'''Ni(η -P RCl)][TEF] (R=Ph (2 f), tBu (2 g)). In the reaction of 1 with [Br P] , an analogous compound is observed only as an intermediate and the final product is an unexpected dinuclear complex [{Cp'''Ni} (μ,η :η :η -P Br )][TEF] (3 a). A similar product [{Cp'''Ni} (μ,η :η :η -P (2,2'-biphen)Cl)][GaCl ] (3 b) is obtained, when 2 d[GaCl ] is kept in solution for prolonged times. Although the central structural motif of 2 a-g consists of a "butterfly-like" folded P ring attached to a {Cp'''Ni} fragment, the structures of 3 a and 3 b exhibit a unique asymmetrically substituted and distorted P 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.