Structure of Molecular PNO, Matrix Isolation and ab initio Calculations

Molecular PNO is formed upon photolysis of PN and O3 in an argon matrix. From the IR spectrum its structure can be formulated as {article}{amssymb}{empty}{document}P arrayc---\\[-11pt]---\\[-10pt]1pt---\ N^⊕ 1pt--- O^⊖{document} , since a band at ṽ = 1755 cm−1 can only be assigned to a NO vibration. This structure contradicts chemical intuition, according to which the isomer NPO should be more stable, but is in agreement with the results of quantum chemical calculations, which show that PNO is 22 kJ mol−1 more stable than NPO.