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.

Insertion of Phosphenium Ions into a Bicyclo[1.1.0]Tetraphosphabutane Iron Complex

“…The fact that one of the signals remains unaffected by the broadening within the whole temperature range, which we tentatively attribute to the Ph 2 P unit in 2a , indicates that, at room temperature, 2a might be the major component and that the Ph 2 P unit is interchanged between the two wingtip phosphorus atoms in a fast process on the NMR time scale. A similar behaviour was observed for [(Cp Ar Ni) 2 (η 3:3 -P 5 R 2 )][GaCl 4 ] (Cp Ar = C 5 (C 6 H 4 -4-Et) 5 , R = iPr and 2,4,6-Me 3 C 6 H 2 ) [ 32 ] as well as for [{Cp‴Fe(CO) 2 } 2 (µ,η 1:1 -P 4 H)] + —the protonated complex of 1 [ 12 ]. According to DFT calculations in 2a , the Ph 2 P unit binds only to one wing-tip phosphorus atom (vide infra).…”

Metal Free Phosphorus Butterfly Compounds

“…After reaction in toluene at −35 °C, the more hindered derivative 33 could be synthesized in 37 % yield using K[Cp Ar ], while the i Pr substituted 32 was found unstable and was isolated only trapping it as a GaCl 3 adduct (Scheme 12). [33] …”

“…Synthesis of 32 and 33. [33] in 37 % yield using K[Cp Ar ], while the iPr substituted was found unstable and was isolated only trapping it as a GaCl 3 adduct (Scheme 12). [33]…”

Cationic Functionalisation by Phosphenium Ion Insertion

“…Examples of the latter are alkylation reactions of [(L)Co(η 3 ‐P 3 )] [15] or [(L)Rh(η 1 :η 2 ‐P 4 R)] [16] (L=MeC(CH 2 PPh 2 ) 3 ). Furthermore, it was shown only recently that derivatives of I can be reacted with highly reduced metal units to yield cationic polyphosphorus compounds [17] . An alternative approach, however, the reactivity of polyphosphorus complexes towards phosphenium cations, has not been investigated so far.…”

“…Inspired by the results obtained on the electrophilic functionalisation of P 4 by the Krossing group (see above), we envisioned the P 4 isolobal polyphosphorus complex [Cp′′′Ni(η 3 ‐P 3 )] ( 1 , Cp′′′=1,2,4‐ t Bu 3 C 5 H 2 ) [11g,e] (Scheme 1) as a suitable starting material for such investigations. Although the recently reported coordinative transformation of derivatives of I is so far limited to P 5 R 2 moieties, [17] our approach would allow for the preparation of yet unknown cyclo ‐P 4 R 2 units. Moreover, if we could demonstrate this reactivity on 1 with success, this approach would potentially open a general way to cationic polyphosphorus ligands of different sizes, as a large variety of polyphosphorus ligand complexes already exists.…”