Synthesis and Characterization of <i>N</i>,<i>N</i>′‑Bismesityl Phenanthrene-9,10-diimine and Imine–Nitrone

The sterically bulky compounds N,N′-bismesityl phenanthrene-9,10-diimine [1] and imine–nitrone [2] were synthesized. To the best of our knowledge, this is the first report of the synthesis of a bulky steric imine–nitrone accessed from the secondary ketimine using urea hydrogen peroxide over methyltrioxorhenium catalyst. Purified compounds were characterized using 1H and 13C NMR, high-resolution mass spectrometry, and infrared spectrometry. We report the first crystal structure of compound 1. Detailed IR bands of compounds 1 and 2 were assigned by comparing experimentally measured spectra to individually animated modes of quantum mechanically computed spectra. We believe these compounds may be of use as bidentate ligands in the synthesis of novel organometallic compounds. The asymmetric N and O coordination sites of compound 2 might impart interesting electronic effects to organometallic compounds compared to the symmetric N,N′-coordination sites of compound 1.