Hydrogen-Bonded Complex of the Parent Phosphinidene

Area of Science:

• Chemical Physics
• Matrix Isolation Spectroscopy
• Computational Chemistry

Background:

• The diatomic molecule phosphinidene (PH) is highly reactive and a parent compound for phosphinidenes.
• Hydrogen bonding interactions involving highly reactive species are not well-understood.
• Characterizing such interactions provides insight into chemical bonding and reactivity.

Purpose of the Study:

• To characterize a rare hydrogen-bonded complex of phosphinidene (PH) with hydrogen chloride (HCl).
• To investigate the reactivity of the PH-HCl complex.
• To understand the role of the phosphorus atom in hydrogen bonding.

Main Methods:

• Photolysis of chlorophosphine (H2PCl) in an argon matrix at 10 K.
• Infrared (IR) spectroscopy for characterization.
• Quantum chemical calculations (UCCSD(T)-F12a/haTZ) for theoretical analysis.
• Photoexcitation experiments to study reactivity.

Main Results:

• A molecular complex of PH and HCl (HP···HCl) was successfully generated and characterized.
• Quantum chemical calculations and IR spectra confirmed the phosphorus atom as a hydrogen bond acceptor.
• The binding energy (D0) of the complex was determined to be -0.6 kcal mol⁻¹.
• The PH-HCl complex exhibits H-Cl bond insertion upon photoexcitation, reforming H2PCl.
• The complex demonstrated instability in the presence of N2 and HCl, forming more stable complexes.

Conclusions:

• The phosphorus atom in phosphinidene (PH) can act as a hydrogen bond acceptor.
• The PH-HCl complex displays unique photochemical reactivity, including bond insertion.
• The stability of the PH-HCl complex is influenced by competing interactions with other molecules.