title: Electron delocalization in the radical cation of 1,3,6,8-tetraazatricyclo[4.4.1.1(3,8)]dodecane, a 4-nitrogen-7-electron system.
abstract: The radical cation of 1,3,6,8-tetraazatricyclo [4.4.1.1(3,8)]dodecane (TTD) has been studied using magnetic resonance and optical spectroscopic methods and computational techniques. With the help of deuterated isotopomers, assignments of EPR and resonance Raman spectra could be unequivocally established. The results demonstrate that the radical cation has D(2d) symmetry, and instantaneous electron delocalization over the four equivalent nitrogen atoms occurs. This extensive delocalization in a completely saturated system is a unique feature of the TTD radical cation. The spectroscopy of TTD, in contrast to that of simpler diamines such as 1,4-diaza[2.2.2]bicyclooctane, simultaneously reveals the consequences of orbital interactions through space and through bonds. The relationship between nitrogen pyramidalization and hyperfine coupling constants in nitrogen-centered radical cations with a number of different bonding arrangements is reviewed.
authors.affiliation: Institute of Molecular Chemistry, University of Amsterdam, Nieuwe Achtergracht 129, NL-1018 WS Amsterdam, The Netherlands.
authors.forename: Jurriaan M
authors.initials: JM
authors.lastname: Zwier
authors.forename: Albert M
authors.initials: AM
authors.lastname: Brouwer
authors.forename: Tamás
authors.initials: T
authors.lastname: Keszthelyi
authors.forename: Gurusamy
authors.initials: G
authors.lastname: Balakrishnan
authors.forename: Jesper F
authors.initials: JF
authors.lastname: Offersgaard
authors.forename: Robert
authors.initials: R
authors.lastname: Wilbrandt
authors.forename: Frédérique
authors.initials: F
authors.lastname: Barbosa
authors.forename: Urs
authors.initials: U
authors.lastname: Buser
authors.forename: Jérôme
authors.initials: J
authors.lastname: Amaudrut
authors.forename: Georg
authors.initials: G
authors.lastname: Gescheidt
authors.forename: Stephen F
authors.initials: SF
authors.lastname: Nelsen
authors.forename: Charles D
authors.initials: CD
authors.lastname: Little