P–P condensation reactions in the coordination sphere of cobalt give access to unique organyl-substituted pentaphosphido complexes.

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.

[LCRP((PhP)2C2H4)][OTf] (4 a,b[OTf]) and [LCiPrP(PPh2)2][OTf] (5 b[OTf]) were prepared from the reaction of imidazoliumyl‐substituted dipyrazolylphosphane triflate salts [LCRP(pyr)2][OTf] (3 a,b[OTf]; a: R=Me, b=iPr; LCR=1,3‐dialkyl‐4,5‐dimethylimidazol‐2‐yl; pyr=3,5‐dimethylpyrazol‐1‐yl) with the secondary phosphanes PhP(H)C2H4P(H)Ph) and Ph2PH. A stepwise double P−N/P−P bond metathesis to catena‐tetraphosphane‐2,3‐diium triflate salt [(Ph2P)2(LCMeP)2][OTf]2 (7 a[OTf]2) is observed when reacting 3 a[OTf] with diphosphane P2Ph4. The coordination ability of 5 b[OTf] was probed with selected coinage metal salts [Cu(CH3CN)4]OTf, AgOTf and AuCl(tht) (tht=tetrahydrothiophene). For AuCl(tht), the helical complex [{(Ph2PPLCiPr)Au}4][OTf]4 (9[OTf]4) was unexpectedly formed as a result of a chloride‐induced P−P bond cleavage. The weakly coordinating triflate anion enables the formation of the expected copper(I) and silver(I) complexes [(5 b)M(CH3CN)3][OTf]2 (M=Cu, Ag) (10[OTf]2, 11[OTf]2).

A ternary Ni2Si2P8 cluster compound is formed selectively by thermolysis of a well-defined nickel complex. This reaction illustrates a potentially useful strategy for the preparation of heteroatom-doped transition metal-phosphide clusters.