Three-electron .sigma. bonding in the radical cation from 1,3,6,8-tetraazatricyclo[4.4.1.13,8]dodecane

Studies on Radical Cations I. Molecular and electronic structure of [3]radialene cation produced by γ‐irradiation in condensed phase

“…l3J']dodecane, for which a D2&omer (electronic symmetry 2B2) competes with a C2v-isomer (electronic symmetry 2B, or 2B2) [37]. Experimentally, however, the C2,-isomer is favoured in condensed phase as it exhibits stronger charge localization, allowing greater solvent-solute interaction [37] [38]. On this basis 10' is clearly favoured over 9+ in condensed media, in line with our spectral assignment given above.…”

“…The situation is reminiscent of that encountered for the radical cation of 1,3,6,8tetraazatricyclo t4.4.1. l3J']dodecane, for which a D2&omer (electronic symmetry 2B2) competes with a C2v-isomer (electronic symmetry 2B, or 2B2) [37]. Experimentally, however, the C2,-isomer is favoured in condensed phase as it exhibits stronger charge localization, allowing greater solvent-solute interaction [37] [38].…”

Structure of Gas Phase Radical Cation of 1,3,6,8-Tetraazatricyclo[4.4.1.13,8] Dodecane Determined from Zero Kinetic Energy Photoelectron Spectroscopy

“…Nelsen and Buschek first recorded the electron spin resonance spectrum of TTD •+ in the condensed phase . Later, based on semiempirical quantum mechanical calculations, Nelsen, et al proposed unequal NCH 2 CH 2 N distances caused by a three-electron σ-bond, similar to the type demonstrated by Alder in some bicyclic diamine radical cations . With more advanced technology, including electron−nuclear double resonance (ENDOR) spectroscopy and a variety of deuterated compounds, the most recent work by Zwier et al concluded that there was a single energy minimum with D 2 d symmetry …”

Towards In‐Plane Delocalized 4N/7e Radical Cations and 4N/6e Dications – One‐/Two‐Electron Oxidation of Proximate‐Parallel Bis(N,N'‐bicyclic)‐bishydrazines

“…Half-caged, rather flexible bis(N,NЈ-bicyclic) bishydrazines (9,10) evolved as the structurally closest synthetically [a] To put the bonding motifs C and D into perspective, through-space (TS) 2N/3e homoconjugation [15,16] and through-bond (TB) intramolecular electron transfer in bis(hydrazyl) radical cations are well documented. [10,17] For the generation of TS 4N/7(6)e cations, urotropin homologues such as the [1 4 .2 2 ] (TTD [18] )/[2 4 .3 2 ]/[3 6 ]adamanzanes [19] seemed promising candidates, since they readily offer conformations with all four n-lobes pointing into the cage. [20] In fact, for the TTD radical cation, a very recent reinvestigation established three-dimensional TS/TB delocalization of seven electrons over four equivalent nitrogen atoms.…”