Hydrogen-Bonded π Complexes between Phosphaethyne and Hydrogen Chloride

Abstract

The highly labile complexes between phosphaethyne (HCP) and hydrogen chloride (HCl) with 1:1 and 1:2 stoichiometries have been generated in Ar and N 2 matrices at 10 K through laser photolysis of the molecular precursors 1-chlorophosphaethene (CH 2 PCl) and dichloromethylphosphine (CH 3 PCl 2 ), respectively. The IR spectrum of the 1:1 complex suggests the preference of a single "T-shaped" structure in which HCl acts as the hydrogen donor that interacts with the electron-rich C�P triple bond. In contrast, three isomeric structures for the 1:2 complex bearing a core structure of the "T-shaped" 1:1 complex are present in the matrix. The spectroscopic identification of these rare HCP πelectron complexes is supported by D-isotope labeling and the quantum chemical calculations at the CCSD(T)-F12a/cc-pVTZ-F12 level of theory.

Hydrogen‐Bonded Complex of the Parent Phosphinidene

“…No IR bands for the two free monomers were observed in the spectrum, suggesting the qualitative conversion of H 2 PCl to HP⋅⋅⋅HCl in the matrix under the irradiation conditions. The observed red‐shift for the H−Cl stretching mode (ν(HCl)) in HP⋅⋅⋅HCl (Δν(HCl)=−101.5 cm −1 ) is comparable to those found for the other HCl complexes with HCCH (Δν(HCl)=−124 cm −1 ) [29] and HCP (Δν(HCl)=−122.8 cm −1 ), [30] in which HCl acts as a hydrogen bond donor. Therefore, it is very likely that HCl also serves as the hydrogen bond donor to the phosphorus atom in the HP⋅⋅⋅HCl complex.…”