# Double E─H Bond Activation of Ammonia and Water by Cyclic Gallaphosphene L(OCP)GaPGaL

## TL;DR

A cyclic gallaphosphene compound activates ammonia and water bonds at room temperature, forming new heterocycles with protonated phosphorus atoms.

## Contribution

A new reaction mechanism for E─H bond activation using a cyclic gallaphosphene compound is demonstrated.

## Key findings

- Cyclic gallaphosphene reacts with ammonia and water to form protonated heterocycles.
- The reaction involves polar Ga─P bonds and an electrophilic carbon center in the PCO unit.
- Quantum calculations confirm bimolecular processes involving additional ammonia molecules.

## Abstract

Cyclic gallaphosphene L(PCO)GaPGaL 1 (L = HC[C(Me)NAr]2; Ar = 2,6‐i‐Pr2‐C6H3) selectively reacts with NH3 and H2O at ambient temperature with twofold N─H and O─H bond activation and formation of compounds LGa(μ‐PH)(μ‐NHC(O)PH)GaL 2 and LGa(μ‐PH)(μ‐OC(O)PH)GaL 3. Both nucleophilic P atoms of 1 are protonated in these reactions, while the electrophilic carbon atom of the bridging PCO unit binds to the remaining NH group / O atom. The formation of heterocycles 2 and 3, which were characterized by heteronuclear NMR (1H, 13C{1H}, 31P{1H}) and IR spectroscopy, elemental analysis, and single‐crystal X‐ray diffraction (sc‐XRD), is only possible due to a beneficial interplay between the polar Ga─P double bond and the electrophilic nature of the C center in the bridging PCO unit. The reaction mechanism and energetics of the NH3 reaction was investigated in detail by quantum chemical calculations, which also highlight the importance of bimolecular reaction processes with the involvement of an additional NH3 molecule.

Cyclic gallaphosphene 1 undergoes a twofold E─H bond activation with ammonia and water via a beneficial interplay between the polar “GaPGa” unit and the electrophilic nature of the C center in the bridging PCO unit, yielding six‐membered heterocycles 2 and 3, in which both nucleophilic phosphorus atoms are protonated.