The new oxygen‐bridged geminal Si/P Frustrated Lewis Pair (FLP) tBu2P−O−Si(C2F5)3 (2) is able to reversibly bind carbon dioxide at ambient temperature. We compared its reactivity towards benzil, but‐3‐en‐2‐one, nitriles and phenylacetylene to that of the Al/P FLP tBu2P−O−AlBis2 (Bis=−CH(SiMe3)2) (1). When reacted with benzil, both, 1 and 2, form the 1,2‐addition product, but in the Si/P FLP 2, the second carbonyl function additionally binds to the silicon atom. With but‐3‐en‐2‐one 2 forms the 1,2‐addition product, while 1 binds in 1,4‐position. The reaction with acetonitrile yielded an unexpected etheneimine adduct for both systems, while only 1 reacted with tert‐butylnitrile. With benzonitrile and acrylonitrile, 2 showed reversible addition to the C≡N bond and 1 forms a stable adduct with benzonitrile. Solely 1 shows reactivity towards phenylacetylene affording a mixture of the CH deprotonation adduct tBu2P(H)−O−AlBis2(CCPh) and the FLP −C≡C 1,2‐addition adduct under ring formation. All compounds were characterized by multinuclear NMR spectroscopy, XRD and elemental analysis.

In this contribution, we report on the “free” [P­(C2F5)2F2]− ion and its ligand properties in transition metal complex chemistry. For this purpose, Ag­[P­(C2F5)2F2] was treated with [{(Et2N)3PN}3PNHC­(CH3)3]Cl ([EtP4H]­Cl) to yield [EtP4H]­[P­(C2F5)2F2], featuring a weakly coordinating phosphazenium cation. Due to the weak interaction between the cation and anion, the [P­(C2F5)2F2]− ion meets the so-called pseudo-gas-phase conditions. To determine the Tolman electronic parameter, [EtP4H]­[Ni­(CO)3{P­(C2F5)2F2}] was prepared from [EtP4H]­[P­(C2F5)2F2] and [Ni­(CO)4], facilitating the classification of the P­(C2F5)2F2 moiety as a moderately π-acidic ligand. By treatment of [EtP4H]­[P­(C2F5)2F2] with [AuCl­(tht)], the neutral tetrahydrothiophene ligand was substituted by the phosphoranide ion, yielding [EtP4H]­[AuCl­{P­(C2F5)2F2}]. When Ag­[P­(C2F5)2F2] 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(C2F5)2F2 moiety, as further demonstrated by the reactions of Ag­[P­(C2F5)2F2] with [FeCl­(CO)2Cp], [FeCl­(CO)2Cp*], and [PdCl2(NCMe)2]. Surprisingly, P­(C2F5)2F demonstrated fluorinating abilities toward [FeCl­(CO)2Cp], [FeCl­(CO)2Cp*], [AuCl­(tht)], and [PdCl2(NCMe)2]. Apparently, fluorido transition metal complexes were generated in situ under the formation of P­(C2F5)2Cl. The fluorido iron and palladium complexes transfer their fluoride ions onto P­(C2F5)2F, yielding the respective phosphoranido complexes, featuring the P­(C2F5)2F2 moiety.