Functionalization of Pentaphosphorus Cations via Complexation

The reactivity of pentaphosphorus cations [P₅R₂]⁺ (R = Cy, iPr, Mes) cations with cyclopentadienyliron, -cobalt and -nickel complexes has been investigated. Reaction of [Cp^ArFe(µ-Br)]₂ (Cp^Ar = C₅(C₆H₄-4-Et)₅) with [P₅R₂][GaCl₄] (R = iPr and 2,4,6-Me₃C₆H₂ (Mes)) affords bicyclo[1.1.0]pentaphosphanes (1-R, R = iPr, Mes), showing an unsymmetrical “butterfly” structure. The same products 1-R are formed from K[Cp^Ar] and [P₅R₂][GaCl₄]. Cationic complexes [Cp^ArCo(η⁴-P₅R₂)][GaCl₄] (2-R[GaCl₄]) and [(Cp^ArNi)₂(η^3:3-P₅R₂)][GaCl₄] (3-R[GaCl₄], R = iPr and Cy) are obtained from [P₅R₂][GaCl₄] and [Cp^ArM(µ-Br)]₂ (M = Co, Ni) as well as by using low valent “CpArM^I’’ sources. Anion metathesis of 2-R[GaCl₄] and 3-R[GaCl₄] was achieved with Na[BArF₂₄] (BArF₂₄ = tetrakis[3,5-bis(trifluoromethyl)phenyl]borate). The P₅ framework of the resulting salts 2-R[BArF₂₄] can be further functionalized with nucleophiles. Thus, reaction with [Et₄N]X (X = CN, Cl) gives unprecedented chloride and cyano-functionalized complexes, while organo-functionalization was achieved with CyMgCl.