Functionalization of Pentaphosphorus Cations by Complexation

Abstract

The chemistry of polyphosphorus cations has rapidly developed in recent years, but their coordination behavior has remained mostly unexplored. Herein, we describe the reactivity of [P5R2]+ cations with cyclopentadienyl metal complexes. The reaction of [CpArFe(μ-Br)]2 (CpAr=C5(C6H4-4-Et)5) with [P5R2][GaCl4] (R=iPr and 2,4,6-Me3C6H2 (Mes)) afforded bicyclo[1.1.0]pentaphosphanes (1-R, R=iPr and Mes), showing an unsymmetric “butterfly” structure. The same products 1-R were formed from K[CpAr] and [P5R2][GaCl4]. The cationic complexes [CpArCo(η4-P5R2)][GaCl4] (2-R[GaCl4], R=iPr and Cy) and [(CpArNi)2(η3:3-P5R2)][GaCl4] (3-R[GaCl4]) were obtained from [P5R2][GaCl4] and [CpArM(μ-Br)]2 (M=Co and Ni) as well as by using low-valent “CpArMI” sources. Anion metathesis of 2-R[GaCl4] and 3-R[GaCl4] was achieved with Na[BArF24]. The P5 framework of the resulting salts 2-R[BArF24] can be further functionalized with nucleophiles. Thus reactions with [Et4N]X (X=CN and Cl) give unprecedented cyano- and chloro-functionalized complexes, while organo-functionalization was achieved with CyMgCl.