INTRAMOLECULAR EXCHANGE COUPLING OF ARYLNITRENES BY OXYGEN

Article abstract of DOI:10.1002/poc.610070905

A series of m,n'-diazidodiphenyl ethers (m -1, and also showed a weak dinitrene quintet spectrum with /D/hc/=0.162 cm^-1 having ESR spectral intensity vs temperature dependence (Curie law) consistent with either a high-spin ground state or a very small singlet-quintet gap.Di(3-azidophenyl) ether gave a strong mononitrene peak with /D/hc/=0.996 cm^-1 and a quintet dinitrene ESR spectrum (/D/hc/=0.162 cm^-1) which exhibited non-linear Curie law intensity behavior consistent with the quintet being a thermally populated excited state 40 cal mol^-1 above a singlet ground state.Di(4-azidophenyl) ether gave a strong mononitrene peak with /D/hc/=0.961 cm^-1, but no observable spectrum related to a high-spin open-shell dinitrene.The results are consistent with oxygen being a weak exchange coupling linker in pi-conjugated open-shell molecules.The observed ground-state spin multiplicities are in accord with qualitative superexchange and connectivity models, despite any perturbations due to resonance effects between the oxygen linker and p-nitrene sites.