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231.
Juanxia Kang Yongcheng Wang Jingjing Wu Zhiming Zhu 《International journal of quantum chemistry》2020,120(5):e26109
In order to further explore the detailed reaction mechanism of carbon dioxide activated by [Re(CO)2]+ complex, CCSD(T) methods was performed to determine related potential energy surface (PES). Crossing point is determined by using a partially optimized method. The result shows that larger spin-orbital coupling (155.37 cm−1) and intersystem crossing probabilities in spin-forbidden region causes the electron to spin flip at the minimum energy crossing point and access to the lower singlet PES. Nonadiabatic rate constant k is estimated to be quite rapid, so transition state (1TS1) is rate-controlled steps. In addition, the electronic structure of oxygen-atom transfer process is further analyzed by localized molecular orbital and Mayer bond order. The analysis finds that the form of main bonding orbital is the electron contribution from the p(O) in CO2 to the empty d(Re) orbital. 相似文献
232.
Junjun Wu Lu Gem Gao Zoltan Varga Xuefei Xu Wei Ren Donald G. Truhlar 《Angewandte Chemie (International ed. in English)》2020,59(27):10826-10830
Faced with the contradictory results of two recent experimental studies [Jara‐Toro et al., Angew. Chem. Int. Ed. 2017 , 56, 2166 and Chao et al., Angew. Chem. Int. Ed. 2019 , 58, 5013] of the possible catalytic effect of water vapor on CH3OH + OH reaction, we report calculations that corroborate the conclusion made by Chao et al. and extend the rate constant evaluation down to 200 K. The rate constants of the CH3OH + OH reaction catalyzed by a water molecule are computed as functions of temperature and relative humidity using high‐level electronic structure and kinetics calculations. The Wuhan–Minnesota Scaling (WMS) method is used to provide accurate energetics to benchmark a density functional for direct dynamics. Both high‐frequency and low‐frequency anharmonicities are included. Variational and tunneling effects are treated by canonical variational transition state theory with multidimensional small‐curvature tunneling. And, most significantly, we include multistructural effects in the rate constant calculations. Our calculations show that the catalytic effect of water vapor is not observable at 200–400 K. 相似文献
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Tzu‐Yu Chen Jinfeng Chen Yijie Tang Jiahai Zhou Yisong Guo Wei‐chen Chang 《Angewandte Chemie (International ed. in English)》2020,59(19):7367-7371
N‐alkylisonitrile, a precursor to isonitrile‐containing lipopeptides, is biosynthesized by decarboxylation‐assisted ‐N≡C group (isonitrile) formation by using N‐alkylglycine as the substrate. This reaction is catalyzed by iron(II) and 2‐oxoglutarate (Fe/2OG) dependent enzymes. Distinct from typical oxygenation or halogenation reactions catalyzed by this class of enzymes, installation of the isonitrile group represents a novel reaction type for Fe/2OG enzymes that involves a four‐electron oxidative process. Reported here is a plausible mechanism of three Fe/2OG enzymes, Sav607, ScoE and SfaA, which catalyze isonitrile formation. The X‐ray structures of iron‐loaded ScoE in complex with its substrate and the intermediate, along with biochemical and biophysical data reveal that ‐N≡C bond formation involves two cycles of Fe/2OG enzyme catalysis. The reaction starts with an FeIV‐oxo‐catalyzed hydroxylation. It is likely followed by decarboxylation‐assisted desaturation to complete isonitrile installation. 相似文献
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《Arabian Journal of Chemistry》2020,13(1):227-241
A new type of magnetically-separable nanocatalyst was prepared through the immobilization of phosphomolybdic acid (H3PMo12O40) in 10–30 wt.% on the surface of core-shell zirconia-coated magnetite nanoparticle (nano-Fe3O4@ZrO2). The developed heterogeneous nano-sized acid catalyst named nano-Fe3O4@ZrO2 supported PMA (or n-Fe3O4@ZrO2/PMA) was characterized using several techniques such as FT-IR, XRD, FE-SEM, VSM, EDX, TEM and TGA. The characterization data derived from FT-IR spectroscopy exhibited that H3PMo12O40 species on the support retained their Keggin structures. Additionally, the potentiometric titration with n-butylamine was employed to measure the acidity content of the as-obtained catalyst. Surprisingly, this novel active solid acid catalyst displayed to have a higher number of surface active sites compared to its homogeneous analogues. Besides, the catalytic activity of the catalyst was evaluated in multicomponent reactions (MRCs) for the rapid and efficient one-pot synthesis of 2, 4, 5-trisubstituted and 1, 2, 4, 5-tetrasubstituted imidazoles in high yields and selectivity. The sample of 20 wt.% displayed higher acidity content which led to its enhanced activity in the catalytic transformation. Moreover, the catalyst could be easily reused without deactivation after five runs, which made it a promising catalyst for practical and large-scale applications. This outstanding reusability was ascribed to the strong attachment of PMA molecules on the n-Fe3O4@ZrO2 support material. 相似文献
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