- Optical spectra of protected diamine 10-bond-bridged intervalence radical cations related to N,N,N′,N′-tetraalkylbenzidine
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The optical absorption spectra of the delocalized intervalence radical cations of seven o,o′-linked benzidine derivatives that have the nitrogens protected as 9-(9-aza-bicyclo[3.3.1]nonan-3-one) derivatives are discussed and compared with that of the p-phenylene radical cation. The linking units are CH2, CH2CH2, NMe, S, SO2, and C=O, and we also studied H,H (the unlinked benzidine). The lowest-energy absorption band is assigned as the transition from the antibonding combination of symmetrical N and aromatic orbitals to the antibonding combination of the antisymmetric N and aromatic orbitals using TD-DFT calculations, and a good correlation between the observed transition energies and those calculated using the simple Koopmans theorem-based "neutral in-cation geometry" calculations on the UB3LYP/6-31G* structures is found. The use of the two-state model that equates the electronic interaction through the bridge between the amino groups with half of the lowest transition energy is seriously incorrect for these and other delocalized intervalence compounds. The problem of extracting the electronic interactions that actually are involved from calculated transition energies is discussed.
- Nelsen, Stephen F.,Luo, Yun,Weaver, Michael N.,Lockard, Jenny V.,Zink, Jeffrey I.
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p. 4286 - 4295
(2007/10/03)
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- Substituted dibenzothiophenes
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This disclosure described novel derivatives of dibenzothiophene, dibenzothiophene sulfoxide, dibenzothiophene sulfone, thioxanthene, thioxanthene sulfoxide and thioxanthene sulfone which are active as modulators of the mammalian immune response system.
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- The Insertion and Extrusion of Heterosulfur Bridges. XII. Selectivity and Side Reactions in the Bridging Process
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1-Phenylnaphthalene undergoes sulfur bridging at 500 deg C in the presence of hydrogen sulfide and a heterogeneous catalyst to produce benzonaphthtothiophene (13percent). 3-Methylphenanthrene and 9-formylphenanthrene diethyl acetal (7b) give sulfur bridging to produce phenanthrothiophene, i.e. with loss of the ring substituent.Additionally, 7b hydrogenolyses to 9-methylphenanthrene.With decadeuteriobiphenyl as a substrate, the dibenzothiophhene formed, as well as biphenyl recovered, is largely devoid of deuterium label.Confirmation that benzene and toluene react under sulfur-bridging conditions is presented.
- Klemm, L. H.,Pou, Sovitj,Detlefsen, W. D.,Higgins, Clay,Lawrence, Ross F.
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p. 1293 - 1296
(2007/10/02)
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