The vibration-rotation spectra of C-13 monosubstituted acetylene, (CCH2)-C-12-C-13, have been recorded in the region between 450 and 3200 cm(-1) with an effective resolution ranging from 0.004 to 0.006 cm(-1). A total of about 5300 rovibrational transitions have been assigned to 53 bands involving the bending states up to nu(t) = nu(4) + nu(5) = 4, allowing the characterization of the ground state and of 30 vibrationally excited states. All the bands involving states up to nu(t) = 3 have been analyzed simultaneously by adopting a model Hamiltonian which takes into account the vibration and rotation l-type resonances. The derived spectroscopic parameters reproduce the transition wavenumbers with a RMS value of the order of the experimental uncertainty. Using the same model larger discrepancies between observed and calculated values have been obtained for transitions involving states with nu(t) = 4. These could be satisfactorily reproduced by only adopting, in addition to the previously determined parameters which were constrained in the analysis, a set of effective constants for each vibrational manifold. (C) 2002 Elsevier Science (USA).
The vibration-rotation spectra of C-13 monosubstituted acetylene, (CCH2)-C-12-C-13, have been recorded in the region between 450 and 3200 cm(-1) with an effective resolution ranging from 0.004 to 0.006 cm(-1). A total of about 5300 rovibrational transitions have been assigned to 53 bands involving the bending states up to nu(t) = nu(4) + nu(5) = 4, allowing the characterization of the ground state and of 30 vibrationally excited states. All the bands involving states up to nu(t) = 3 have been analyzed simultaneously by adopting a model Hamiltonian which takes into account the vibration and rotation l-type resonances. The derived spectroscopic parameters reproduce the transition wavenumbers with a RMS value of the order of the experimental uncertainty. Using the same model larger discrepancies between observed and calculated values have been obtained for transitions involving states with nu(t) = 4. These could be satisfactorily reproduced by only adopting, in addition to the previously determined parameters which were constrained in the analysis, a set of effective constants for each vibrational manifold. (C) 2002 Elsevier Science (USA).
Isotopic probes for ruthenium-catalyzed olefin metathesis
作者:Justin A. M. Lummiss、Adrian G. G. Botti、Deryn E. Fogg
DOI:10.1039/c4cy01118j
日期:——
13C-labelled Grubbs catalysts, RuCl2(L)(PCy3)(13CHR) (R = H, Ph), pinpoint the fate of the methylidene (benzylidene) moiety during metathesis and deactivation.
Diazomethane umpolung atop anthracene: an electrophilic methylene transfer reagent
作者:Maximilian Joost、Wesley J. Transue、Christopher C. Cummins
DOI:10.1039/c7sc04506a
日期:——
exhibit dangerous heat or shock sensitivity. Effective umpolung of the diazomethane unit imbues 1 with electrophilicity at the methylene carbon center. Its reactivity with nucleophiles such as H2CPPh3 and N-heterocyclic carbenes is exploited for CC bond formation with elimination of dinitrogen and anthracene. Similarly, 1 is demonstrated to deliver methylene to a nucleophilic singlet d2 transition metal
将重氮甲烷的末端氮原子正式加成到蒽的 9,10 位会产生 H 2 CN 2 A(1,A = C 14 H 10或蒽)。该腙的合成是由 Carpino 的肼 H 2 N 2 A通过多聚甲醛处理合成的。已发现化合物1是一种易于处理的固体,不会表现出危险的热或冲击敏感性。重氮甲烷单元的有效 umpolung在亚甲基碳中心赋予1亲电性。它与亲核试剂如 H 2 CPPh的反应性3和N-杂环卡宾被开发用于CC键的形成,同时消除了二氮和蒽。类似地, 1被证明可以将亚甲基传递到亲核单线态 d 2过渡金属中心 W(ODipp) 4 ( 2 ),从而产生稳定的亚甲基配合物 [ 2 CH 2 ]。这种行为与 Wittig 试剂 H 2 CPPh 3的行为形成对比,后者是一种更传统的布朗斯台德碱性亚甲基源,在暴露于2时形成亚甲基盐 [MePPh 3 ][ 2 CH]。
Metal alkoxides. Models for metal oxides. 18. Structure, bonding and dynamic behavior of bis(.eta.2-ethylene)hexakis(neopentoxy)ditungsten. Studies of the reversible addition of carbon-carbon double bonds to a tungsten-tungsten triple bond
作者:Stephanie T. Chacon、Malcolm H. Chisholm、Odile Eisenstein、John C. Huffman
DOI:10.1021/ja00048a022
日期:1992.10
Hydrocarbon solutions of W 2 (OCH 2 -t-Bu), and ethylene (≥2 equiv) react at 0 o C to yield W 2 (OCH 2 -t-Bu) 6 (η 2 -C 2 H 4 ) 2 , 1, which has been characterized by NMR studies and a single-crystal X-ray diffraction study. Crystal data for 1 at -155 o C: a=11.754 (4) A, b=31.405 (14) A, c=11.274 (4) A, β=104.96 (2) o and space group P2 1 /c.
W 2 (OCH 2 -t-Bu) 和乙烯 (≥2 当量) 的烃溶液在 0 o C 反应生成 W 2 (OCH 2 -t-Bu) 6 (η 2 -C 2 H 4 ) 2 , 1,已通过核磁共振研究和单晶 X 射线衍射研究表征。1 在 -155 o C 的晶体数据:a=11.754 (4) A,b=31.405 (14) A,c=11.274 (4) A,β=104.96 (2) o 和空间群 P2 1 /c。
Evaluation of the Catalytic Relevance of the CO‐Bound States of V‐Nitrogenase
作者:Chi Chung Lee、Jarett Wilcoxen、Caleb J. Hiller、R. David Britt、Yilin Hu
DOI:10.1002/anie.201800189
日期:2018.3.19
Binding and activation of CO by nitrogenase is a topic of interest because CO is isoelectronic to N2, the physiological substrate of this enzyme. The catalyticrelevance of one‐ and multi‐CO‐boundstates (the lo‐CO and hi‐COstates) of V‐nitrogenase to C−C coupling and N2 reduction was examined. Enzymatic and spectroscopic studies demonstrate that the multiple CO moieties in the hi‐CO state cannot be coupled
Cracking of (5-13C)-n-nonane with quartz wool, silica-alumina and type Y zeolite
作者:Thomas J. Weeks、Irwin R. Ladd、Anthony P. Bolton
DOI:10.1039/f19807600084
日期:——
The cracking mechanism of (5-13C)-n-nonane has been studied over quartzwool, silica—alumina and a typeYzeolite. The products observed at a reaction temperature of 510°C over quartzwool agree reasonably well with the currently accepted mechanism of free radical cracking. Reaction with silica—alumina at 500°C and zeolite at 230°C results in a 13C labelled product distribution which agrees with neither