Cationic Functionalisation by Phosphenium Ion Insertion

The reaction of [Cp′′′Ni(η 3 ‐P 3 )] ( 1 ) with in situ generated phosphenium ions [RR′P] + yields the unprecedented polyphosphorus cations of the type [Cp′′′Ni(η 3 ‐P 4 R 2 )][X] (R=Ph ( 2 a ), Mes ( 2 b ), Cy ( 2 c ), 2,2′‐biphen ( 2 d ), Me ( 2 e ); [X] − =[OTf] − , [SbF 6 ] − , [GaCl 4 ] − , [BAr F ] − , [TEF] − ) and [Cp′′′Ni(η 3 ‐P 4 RCl)][TEF] (R=Ph ( 2 f ), t Bu ( 2 g )). In the reaction of 1 with [Br 2 P] + , an analogous compound is observed only as an intermediate and the final product is an unexpected dinuclear complex [{Cp′′′Ni} 2 (μ,η 3 :η 1 :η 1 ‐P 4 Br 3 )][TEF] ( 3 a ). A similar product [{Cp′′′Ni} 2 (μ,η 3 :η 1 :η 1 ‐P 4 (2,2′‐biphen)Cl)][GaCl 4 ] ( 3 b ) is obtained, when 2 d [GaCl 4 ] is kept in solution for prolonged times. Although the central structural motif of 2 a – g consists of a “butterfly‐like” folded P 4 ring attached to a {Cp′′′Ni} fragment, the structures of 3 a and 3 b exhibit a unique asymmetrically substituted and distorted P 4 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 .