Gallaphosphene L(Cl)GaPGaL: A novel phosphinidene transfer reagent

Gallaphosphene L(Cl)GaPGaL 1 (L=HC[C(Me)N(Ar)]2; Ar=2,6‐iPr2C6H3) reacts with N‐heterocyclic carbenes RNHC (RNHC=[CMeN(R)]2C; R=Me, iPr) to RNHC‐coordinated phosphinidenes RNHC→PGa(Cl)L (R=Me 2 a, iPr 2 b) and with isonitriles RNC (R=iPr, Cy) to 1,3‐phosphaazaallenes L(Cl)GaP=C=N−R (R=iPr 3 a, Cy 3 b), respectively. Quantum chemical calculations reveal that 2 a/2 b possess two localized lone pair of electrons, whereas 3 a/3 b only show one localized lone pair as was reported for gallaphosphene 1. 2 b reacts with 2.5 equivalents of a borane (THF ⋅ BH3) to the NHC‐stabilized phosphinidene‐borane complex [iPrNHC→P(BH2)]2(BH3)3 4 with concomitant formation of LGa(H)Cl 5. 2–5 are characterized by heteronuclear (1H, 13C{1H}, 31P{1H}) NMR and IR spectroscopy, elemental analysis, and single crystal X‐ray diffraction (sc‐XRD). Gallaphosphene 1 serves as a phosphinidene transfer reagent in reactions with RNHCs and isonitriles, to give RNHC‐coordinated phosphinidenes 2 and 1,3‐phosphaazaallenes 3, respectively. NHC‐coordinated phosphinidene 2 b reacted with THF ⋅ BH3 with selective B−H bond activation to the unique NHC‐stabilized borane complex 4.