Electronic structure of PH₂⁻ containing complexes as photoelectron spectroscopy candidates

Phosphine is attracting interest due to the role it plays in extraterrestrial and interplanetary atmospheric environments. Phosphorus hydride anion and neutral van der Waals complexes with CH₄, C₂H₄, HCCH, CO₂, H₂S and NH₃ have been investigated as potential targets for photoelectron spectroscopy using a combination of DSD-PBEP86-D3BJ optimised geometries, W2w energies and Franck–Condon simulations. All anion complexes exhibit hydrogen-bonding interactions and while complexes with CH₄ are weakly bound, showing minimal perturbation upon complexation. All other solvating molecules studied yield sufficient energetic or vibrational structural differences to be differentiable in photoelectron spectra. Most notably, PH₂⁻⋯CO₂ undergoes barrierless nucleophilic addition to form the phosphino formate anion (PH₂COO⁻) and is proposed as one such potential atmospheric sink.