The EPR Spectrum of Triplet Mesitylphosphinidene: Reassignment and New Assignment

Low‐temperature UV‐photolysis of mesitylphosphiranes under highly anaerobic conditions leads to the formation of the triplet mesitylphosphinidene (MesP). The recorded X‐band EPR spectrum of triplet MesP and the derived zero‐field splitting parameter D=4.116 cm−1 differ significantly from those reported previously for this intermediate. New magnetic parameters of mesitylphosphinidene are discussed along with the results of DFT calculations. Finally caught: The EPR spectrum of triplet mesitylphosphinidene and zero‐field splitting parameter D from this spectrum differ significantly from those previously reported in the literature. The presence of the doublet‐hyperfine structure in the EPR spectra provides reliable identification of the mesitylphosphinidene molecule in its triplet state.