title: Limits of delocalization in through-conjugated dinitrenes: aromatization or bond formation?
abstract: [reaction: see text] Dinitrenes 4 and 5 both can form quinonoidal structures by conjugative bond formation. However, ESR spectroscopy detects a thermally populated, excited-state, triplet quinonoidal structure only for 4, with a zero-field splitting of |D/hc| = 0.0822 cm(-)(1), |E/hc| congruent with 0.0 cm(-)(1). The tendency to maintain aromaticity in the additional ring of 5 favors a dinitrene structure (with one less formal pi-bond) over a quinonoidal structure. The thermally populated quintet state of 5 has a zero-field splitting of |D/hc| = 0.287 cm(-)(1), |E/hc| <or= 0.002 cm(-)(1).
authors.affiliation: Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA.
authors.forename: Paul R
authors.initials: PR
authors.lastname: Serwinski
authors.forename: Paul M
authors.initials: PM
authors.lastname: Lahti