Vibrational spectrum and photochemistry of phosphaketene HPCO

The vibrational spectra of the simplest phosphaketene HPCO and its isotopologue DPCO in solid Ar-matrices at 12.0 K have been analyzed with the aid of the computations at the CCSD(T)-F12a/cc-pVTZ-F12 level using configuration-selective vibrational configuration interaction (VCI). In addition to the four IR fundamentals, four overtone and ten combination bands have been unambiguously identified. Furthermore, the photochemistry of HPCO in the matrix has been investigated for the first time. Upon UV-light irradiation (365 or 266 nm), CO-elimination occurs by forming the parent phosphinidene HP that can be trapped by NO to yield the elusive phosphinimine-N-oxyl radical HPNO. In contrast, an excimer laser (193 nm) irradiation of HPCO causes additional decomposition to H and PCO with concomitant formation of the long-sought phosphaethyne HOCP.

Automated summary

The vibrational spectra of HPCO and DPCO in solid Ar-matrices at 12.0 K were analyzed using computational methods, revealing the presence of additional bands beyond the IR fundamentals. The photochemistry of HPCO in the matrix was investigated for the first time, showing different decomposition pathways under UV and excimer laser irradiation.