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161.
Lynch WB Bechtel HA Steeves AH Curley JJ Field RW 《The Journal of chemical physics》2007,126(24):244307
The A1A" state of isocyanogen, CNCN, is observed using photofragment fluorescence excitation spectroscopy in a room temperature cell and in a molecular beam. The spectra are highly congested, but progressions that correspond to the Franck-Condon active C-N-C bending vibration in the excited state are evident. Linewidth measurements indicate that the excited state lifetime is <10 ps. These measurements are consistent with previous ab initio calculations, which predicted a bent excited state with a short lifetime due to predissociation. Although we do not believe that we have observed the origin band of the electronic transition, we place an upper limit of 42,523 cm(-1) on the energy of the excited state zero point level. 相似文献
162.
Jeong SD Hong SJ Park KJ Ham S Sessler JL Lynch V Lee CH 《The Journal of organic chemistry》2007,72(16):6232-6240
New core-modified, meso-alkylidenyl porphyrinoids bearing multiple exocyclic double bonds were synthesized and characterized. The synthesis was accomplished using a typical "3 + 1"-type condensation approach. Stable exocyclic tautomers bearing double bonds at the meso positions, as well the corresponding endocyclic tautomers, were isolated in the case of both thiabenziporphyrin and thiapyriporphyrin products prepared in the course of this study. On the other hand, only the exocyclic tautomer was isolated in the case of the congeneric oxapyriporphyrin and oxabenziporphyrin. Expanded analogues of the exocyclic forms of oxabenziporphyrin and thiabenziporphyrin were also isolated as minor products. A single-crystal X-ray diffraction analysis of the expanded thiabenziporphyrin (20) revealed that all four pyrrole rings displayed an inverted geometry, presumably reflecting the strong hydrogen-bonding extant between the pyrrole N-H proton and the carbonyl group of the malonate moiety in the solid state. On the other hand, the expanded oxabenziporphyrin (14) was found to possess a severely distorted geometry with only one pyrrole ring being inverted. Careful analysis of the structure revealed that the solid-state geometry of the expanded macrocycles correlates well with the internal angle defined by the 2- and 5 substituents and the centers of the furan (14) or thiophene (20) subunits. 相似文献
163.
Hwang-Hsing Chen Jesse A. May Vincent M. Lynch 《Journal of heterocyclic chemistry》1999,36(1):249-256
A series of the title compounds were prepared for evaluation as inhibitors of carbonic anhydrase II. Oxidation of 5-substituted thieno[2,3-b]thiophene-2-sulfonamides provided the first examples of thiophene[2,3-b]thiophene-2-sulfonarnide 6,6-dioxides. These cyclic vinyl sulfones readily underwent addi tion to give predominately that 4,5-cis addition product. 相似文献
164.
Daniel E. Lynch Tim Dougall Graham Smith Karl A. Byriel Colin H. L. Kennard 《Journal of chemical crystallography》1999,29(1):67-73
3-Amino-1,2,4-triazolium (3-AT) 5-nitrofuran-2-carboxylate has been prepared and its x-ray crystal structure reported (a = 12.363(3) Å, b = 12.5720(10) Å, c = 12.8550(10) Å, Pbca, orthorhombic, Z = 8, and D
c = 1.604 mg m–3). The solid-state packing of this organic acid-base salt consists of a three-dimensional hydrogen-bonded network which exhibits a cage-like repeat unit involving both the N(2)–H and N(4)–H sites of 3-AT. A review of five such structures reveals that in all cases the carboxylate groups interact with either of these sites [and the N(31)H2] and form a R
2
2(8) graph set interaction. Analysis of all 3-AT complexes which form this interaction reveals that the hydrogen-bonding distances between the non-hydrogen atoms are not equal [av. 2.712(5) Å and 2.897(5) Å], with the shorter distance being the interaction between the heterocyclic nitrogen and the corresponding carboxylate oxygen. Furthermore, a review of the interactive modes of all 3-AT adducts has been undertaken. 相似文献
165.
Manifestations of pronounced shell effects are discovered when non-axial octupole deformations are added to a harmonic oscillator
model. The degeneracies of the quantum spectra are in good agreement with the corresponding main periodic orbits and winding
number ratios which are found by classical analysis.
Pis’ma Zh. éksp. Teor. Fiz. 69, No. 8, 525–530 (25 April 1999)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
166.
167.
Daniel E. Lynch Ian McClenaghan 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(11):o641-o643
Two chemical isomers of 3‐nitrobenzotrifluoride, namely 1‐(4‐chlorophenylsulfanyl)‐2‐nitro‐4‐(trifluoromethyl)benzene, C13H7ClF3NO2S, (I), and 1‐(4‐chlorophenylsulfanyl)‐4‐nitro‐2‐(trifluoromethyl)benzene, C13H7ClF3NO2S, (II), have been prepared and their crystal structures determined with the specific purpose of forming a cocrystal of the two. The two compounds display a similar conformation, with dihedral angles between the benzene rings of 83.1 (1) and 76.2 (1)°, respectively, but (I) packs in P while (II) packs in P21/c, with C—H⋯O interactions. No cocrystal could be formed, and it is suggested that the C—H⋯O associations in (II) prevent intermolecular mixing and promote phase separation. 相似文献
168.
169.
170.
Michael P. Doyle Doina G. Ene Chad S. Peterson Vince Lynch 《Angewandte Chemie (International ed. in English)》1999,38(5):700-702
The intramolecular addition of a diazo ester group to a triple bond in the presence of chiral dirhodium(II ) carboxamidate catalysts gives macrocyclic lactones with a fused cycloproprene ring [Eq. (a)]. This efficient reaction is characterized by high enantiocontrol (up to 98% ee) and chemoselectivity. 相似文献