m-Phenylenedicarbene and m-Phenylenedinitrene Compounds Having Quintet Ground States

Higuchi¹, in his theoretical studies on hydrocarbons having high spin multiplicities, has suggested that compounds such as m-phenylenedlcarbene (I) and some of its substituted derivatives, e. g. m-phenylene-bis-phenylcarbene (II) should have ground states with four unpaired electrons, namely a quintet state. Recently, the zero-field (esr) splitting parameters (D and E) have been determined for I², II² and for m-phenylenedinitrene (III)². The results of the esr spectra are in agreement with quintet electronic ground states for these molecules^2,3.