Metal‐Free N−H Bond Activation by Phospha‐Wittig Reagents**

Abstract

N-containing molecules are mostly derived from ammonia (NH 3 ). Ammonia activation has been demonstrated for single transition metal centers as well as for low-valent main group species. Phosphinidenes, mono-valent phosphorus species, can be stabilized by phosphines, giving so-called phosphanylidenephosphoranes of the type RP(PR' 3 ). We demonstrate the facile, metal-free NH 3 activation using ArP(PMe 3 ), affording for the first time isolable secondary aminophosphines ArP(H)NH 2 . DFT studies reveal that two molecules of NH 3 act in concert to facilitate an NH 3 for PMe 3 exchange. Furthermore, H 2 NR and HNR 2 activation is demonstrated.

Modulating the reactivity of phosphanylidenephosphoranes towards water with Lewis acids

“…51 Such condensation was also observed for the respective secondary aminophosphanes RP(H)NH 2 (R = Mes*, Mes Ter) upon crystallization. 30 In 2:Mes* , the PO atom distance is in good agreement with phosphine oxides and measures 147.50(45) pm.…”

“…51 Such condensation was also observed for the respective secondary aminophosphanes RP (H)NH 2 (R = Mes*, Mes Ter) upon crystallization. 30 In 2:Mes*, the PvO atom distance is in good agreement with phosphine oxides and measures 147.50 (45) pm. Until two recent reports described the isolation of the stable primary phosphine oxides FcCH 2 P(O)H 2 52 (Fc = ferrocenyl) and (9-hydroxyadamant-4-yl)P(O)H 2 , 39 primary phosphine oxides were generated in situ or proved to be unstable.…”

“…The metal free NH-bond activation of a series of amines including NH 3 was realized at ambient temperature. 30 This was a remarkable finding as NH 3 -activation remains a challenge in transition metal chemistry due to the possible formation of unreactive Werner-type complexes. 31 However, another under-explored potential appears to be the bond activation chemistry of phosphanylidene-σ 4 -phosphoranes through their nucleophilic, yet weakly basic character.…”

Dual Reactivity of a Geometrically Constrained Phosphenium Cation

“…In this respect, it is worth mentioning that the opposite reaction in which phosphinidenes (P I ) activate NH 3 , producing new aminophosphines (P III ), was recently reported. [34] We next proceeded to study the reactivity of [1 + ][OTf] with Et 3 SiH and HBpin. Noteworthy, in contrast to activation of MeOÀ H and Et 2 NÀ H with a protic hydrogen, in Et 3 SiÀ H and HÀ Bpin the hydrogen is hydridic and therefore a possibility for a different activation path was expected.…”

Deoxygenation of chalcogen oxides EO2 (E = S, Se) with phosphaWittig reagents

“…47 These reagents can be used as "masked" phosphinidenes, showing phosphinidenoid reactivity upon PMe3 release. We have demonstrated the facile NH- 48 as well as OH-bond 49 activation at the P(I) center as well as the cleavage of the terminal C(sp 2 )−H bonds of NHOs to give P-substituted NHOs. 50 Utilizing phospha-and arsa-Wittig reagents as pnictinidene transfer reagents, phospha-as well as arsaalumenes 51 -compounds showing E 13 -E 15 multiple bonding 52 -could be generated in the reaction with (Cp*Al)4 (Scheme 2).…”