Reactivity of organic azo-compounds. X. NMR study on azo-hydrazone tautomeric equilibrium in hydroxyazo-compounds

Spin distributions and geometries of the radical cations of sesquinorbornenes and other polycyclic tetraalkylethenes

“…Spin Delocalization in the Radical Cations of Tetraalkyl-Substituted Ethenes. The question of how effective the large polycyclic groups are at delocalizing -spin population in radical cations can be addressed semiquantitatively by employing the method of Fessenden and Schuler36 and Fischer.37 For alkyl-substituted neutral -radicals, these authors have suggested the use of the We first apply eq 2 and 3 to the radical cations of tetramethylethene (18) and hexamethylbenzene (19), which have two and six equivalent carbon -centers, respectively. By setting o(H[Me]) = 1.72 mT38 for 18*+ ( 0* = */2) and 0.645 mT39 for 19,+ (po' = '/6), four equations are obtained, two for each radical cation.…”

“…Also dealt with in the present paper are the radical cations of other ethenes substituted by polycyclic alkyl groups, such as those of adamantylideneadamantane (5),14,15 isopropylideneadamantane (6),16 sesquihomoadamantene (7),17 and 1,2-dimethylhomoadamantene (8). 18 As in the case of 5*+, the low-lying "orbital hole" in the ethene -system of 1*+, 2,+, 4,+ (central double bond), and 6,+-8*+ should partially be filled by a transfer of electrons from the -orbitals (13) (a) Paquette, L. A; Künzer, H.; Green, K. E. J. Am.…”

“…Lozenges with regression line G are from ref 46 [18, EtMeC=CMe2, «-PrMeC=CMe2, /-PrMeC= CMe2, «-BuMeC=CMe2, Z-EtMeC=CMeEt, £-EtMeC=CMeEt, £-EtMeC=CMe-«-Pr, Et2C=CMe2, «-BuEtC=CMe2, Et2C=CMeEt, Et2C=CEt2]. Circles with regression line BH are from ref 45a [23, isopropylidinecyclopentane, bicyclo[5.3.0]dec-l,7-ene, 3-methyltricyclo-[6.2.1,02,7]undec-2,7-ene, 4,5-dipropyl-oct-4-ene] and ref 45b[5,18,22, Zand £-2,3,4,5-tetramethylhex-3-ene]. Squares are from ref 45a[1, 2] and the triangle is from ref 45b[21].…”