Free Difluorobis(pentafluoroethyl)phosphoranide Ion and Its Ligand Properties.

In this contribution, we report on the "free" [P(C 2 F 5 ) 2 F 2 ] - ion and its ligand properties in transition metal complex chemistry. For this purpose, Ag[P(C 2 F 5 ) 2 F 2 ] was treated with [{(Et 2 N) 3 P═N} 3 P═NHC(CH 3 ) 3 ]Cl ([EtP 4 H]Cl) to yield [EtP 4 H][P(C 2 F 5 ) 2 F 2 ], featuring a weakly coordinating phosphazenium cation. Due to the weak interaction between the cation and anion, the [P(C 2 F 5 ) 2 F 2 ] - ion meets the so-called pseudo-gas-phase conditions. To determine the Tolman electronic parameter, [EtP 4 H][Ni(CO) 3 {P(C 2 F 5 ) 2 F 2 }] was prepared from [EtP 4 H][P(C 2 F 5 ) 2 F 2 ] and [Ni(CO) 4 ], facilitating the classification of the P(C 2 F 5 ) 2 F 2 moiety as a moderately π-acidic ligand. By treatment of [EtP 4 H][P(C 2 F 5 ) 2 F 2 ] with [AuCl(tht)], the neutral tetrahydrothiophene ligand was substituted by the phosphoranide ion, yielding [EtP 4 H][AuCl{P(C 2 F 5 ) 2 F 2 }]. When Ag[P(C 2 F 5 ) 2 F 2 ] was treated with [AuCl(tht)], on the other hand, the chloride was substituted. Transmetalation reactions of this type proved to be an efficient transfer method of the P(C 2 F 5 ) 2 F 2 moiety, as further demonstrated by the reactions of Ag[P(C 2 F 5 ) 2 F 2 ] with [FeCl(CO) 2 Cp], [FeCl(CO) 2 Cp*], and [PdCl 2 (NCMe) 2 ]. Surprisingly, P(C 2 F 5 ) 2 F demonstrated fluorinating abilities toward [FeCl(CO) 2 Cp], [FeCl(CO) 2 Cp*], [AuCl(tht)], and [PdCl 2 (NCMe) 2 ]. Apparently, fluorido transition metal complexes were generated in situ under the formation of P(C 2 F 5 ) 2 Cl. The fluorido iron and palladium complexes transfer their fluoride ions onto P(C 2 F 5 ) 2 F, yielding the respective phosphoranido complexes, featuring the P(C 2 F 5 ) 2 F 2 moiety.