A He(I) ultraviolet photoelectron spectroscopic and computational study of the electronic structure of phenyl and pyridinyl diazoketones and diazoesters

The He(I) photoelectron spectra of five phenyl and pyridinyl diazoketones and diazoesters 2a, 2b, 3, 4a, and 4b have been recorded and their structures and orbital energies have been calculated by ab initio methods. Diazoesters 3, 4a, and 4b show a π-π orbital interaction between a π orbital of the aromatic ring and πCN of the diazo moiety which causes a dependence of orbital energies on the CCCN torsional angle. Diazoketones 1, 2a, and 2b …