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 [CpArFe(µ-Br)]2 (CpAr = 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[CpAr] and [P5R2][GaCl4]. Cationic complexes [CpArCo(η4-P5R2)][GaCl4] (2-R[GaCl4]) and [(CpArNi)2(η3:3-P5R2)][GaCl4] (3-R[GaCl4], R = iPr and Cy) are obtained from [P5R2][GaCl4] and [CpArM(µ-Br)]2 (M = Co, 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] (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.