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991.
Infrared spectral results at elevated carbon monoxide pressures suggest that rhodiumdicarbonyl halides and carbon monoxide exist in an equilibrium with the corresponding rhodiumtricarbonyl halides. 相似文献
992.
Donald L. Thompson 《Chemical physics letters》1978,55(3):424-427
The Br + Br2 atom-exchange reaction has been studied using quasiclassical trajectories and a semi-empirical potential-energy surface with shallow, long-range wells. The computed reaction rate coefficient is in good agreement with experiment. The computed reaction activation energy is ? 1 kcal/mole. 相似文献
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General conclusions relating pairwise tallies with positional (e.g., plurality, antiplurality (“vote-for-two”)) election outcomes were previously known only for the Borda Count. While it has been known since the eighteenth century that the Borda and Condorcet winners need not agree, it had not been known, for instance, in which settings the Condorcet and plurality winners can disagree, or must agree. Results of this type are developed here for all three-alternative positional rules. These relationships are based on an easily used method that connects pairwise tallies with admissible positional outcomes; e.g., a special case provides the first necessary and sufficient conditions ensuring that the Condorcet winner is the plurality winner; another case identifies when there must be a profile whereby each candidate is the “winner” with some positional rule. 相似文献
996.
Donald C. Dittmer Bhalchandra H. Patwardhan Edward J. Parker 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-2):79-80
Abstract Simple alkyl substituted thietes are liquids which decompose at room temperature presumably via electrocyclic ring opening to give polymeric material. 相似文献
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999.
Trung Le Hao Nguyen Lisa M. Perez Donald J. Darensbourg Marcetta Y. Darensbourg 《Angewandte Chemie (International ed. in English)》2020,59(9):3645-3649
With the goal of generating anionic analogues to MN2S2 ? Mn(CO)3Br we introduced metallodithiolate ligands, MN2S22? prepared from the Cys‐X‐Cys biomimetic, ema4? ligand (ema=N,N′‐ethylenebis(mercaptoacetamide); M=NiII, [VIV≡O]2+ and FeIII) to Mn(CO)5Br. An unexpected, remarkably stable dimanganese product, (H2N2(CH2C=O(μ‐S))2)[Mn(CO)3]2 resulted from loss of M originally residing in the N2S24? pocket, replaced by protonation at the amido nitrogens, generating H2ema2?. Accordingly, the ema ligand has switched its coordination mode from an N2S24? cavity holding a single metal, to a binucleating H2ema2? with bridging sulfurs and carboxamide oxygens within Mn‐μ‐S‐CH2‐C‐O, 5‐membered rings. In situ metal‐templating by zinc ions gives quantitative yields of the Mn2 product. By computational studies we compared the conformations of “linear” ema4? to ema4? frozen in the “tight‐loop” around single metals, and to the “looser” fold possible for H2ema2? that is the optimal arrangement for binucleation. XRD molecular structures show extensive H‐bonding at the amido‐nitrogen protons in the solid state. 相似文献
1000.
Although oxidative folding of disulfide-rich proteins is often sluggish, this process can be significantly enhanced by targeted replacement of cysteines with selenocysteines. In this study, we examined the effects of a selenosulfide and native versus nonnative diselenides on the folding rates and mechanism of bovine pancreatic trypsin inhibitor. Our results show that such sulfur-to-selenium substitutions alter the distribution of key folding intermediates and enhance their rates of interconversion in a context-dependent manner. 相似文献