排序方式: 共有59条查询结果,搜索用时 15 毫秒
31.
32.
33.
Fernando Pirani David Cappelletti Stefano Falcinelli Diego Cesario Francesca Nunzi Leonardo Belpassi Francesco Tarantelli 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(13):4239-4243
Molecular‐beam scattering experiments and theoretical calculations prove the nature, strength, and selectivity of the halogen bonds (XB) in the interaction of halogen molecules with the series of noble gas (Ng) atoms. The XB, accompanied by charge transfer from the Ng to the halogen, is shown to take place in, and measurably stabilize, the collinear conformation of the adducts, which thus becomes (in contrast to what happens for other Ng‐molecule systems) approximately as bound as the T‐shaped form. It is also shown how and why XB is inhibited when the halogen molecule is in the 3Πu excited state. A general potential formulation fitting the experimental observables, based on few physically essential parameters, is proposed to describe the interaction accurately and is validated by ab initio computations. 相似文献
34.
Jan Wilhelm Joost VandeVondele Vladimir V. Rybkin 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(12):3930-3933
The structure of the hydrated electron is a matter of debate as it evades direct experimental observation owing to the short life time and low concentrations of the species. Herein, the first molecular dynamics simulation of the bulk hydrated electron based on correlated wave‐function theory provides conclusive evidence in favor of a persistent tetrahedral cavity made up by four water molecules, and against the existence of stable non‐cavity structures. Such a cavity is formed within less than a picosecond after the addition of an excess electron to neat liquid water, with less regular cavities appearing as intermediates. The cavities are bound together by weak H?H bonds, the number of which correlates well with the number of coordinated water molecules, each type of cavity leaving a distinct spectroscopic signature. Simulations predict regions of negative spin density and a gyration radius that are both in agreement with experimental data. 相似文献
35.
Valerio Rizzi Daniela Polino Emilia Sicilia Nino Russo Michele Parrinello 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(12):4016-4020
The discovery of effective hydrogen storage materials is fundamental for the progress of a clean energy economy. Ammonia borane (H3BNH3, AB) has attracted great interest as a promising candidate but the reaction path that leads from its solid phase to hydrogen release is not yet fully understood. To address the need for insights in the atomistic details of such a complex solid state process, in this work we use ab‐initio molecular dynamics and metadynamics to study the early stages of AB dehydrogenation. We show that the formation of ammonia diborane (H3NBH2(μ‐H)BH3) leads to the release of NH4+, which in turn triggers an autocatalytic H2 production cycle. Our calculations provide a model for how complex solid state reactions can be theoretically investigated and rely upon the presence of multiple ammonia borane molecules, as substantiated by standard quantum‐mechanical simulations on a cluster. 相似文献
36.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(44):14026-14029
Quantum chemistry is a useful tool in modern approaches to drug and material design, but only when the adopted model reflects a correct physical picture. Paradigmatic is the case of cis ‐diaminodichloroplatinum(II), cis ‐[Pt(NH3)2Cl2], for which the correct simulation of the structural and vibrational properties measured experimentally still remains an open question. By using this molecule as a proof of concept, it is shown that state‐of‐the‐art quantum chemical calculations and a simple model, capturing the basic physical flavors, a cis ‐[Pt(NH3)2Cl2] dimer, can provide the accuracy required for interpretative purposes. The present outcomes have fundamental implications for benchmark studies aiming at assessing the accuracy of a given computational protocol. 相似文献
37.
Camilla Calabrese Weixing Li Giacomo Prampolini Luca Evangelisti Iciar Uriarte Ivo Cacelli Sonia Melandri Emilio J. Cocinero 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(25):8525-8530
Rotational spectra of several difluoromethane–water adducts have been observed using two broadband chirped‐pulse Fourier‐transform microwave (CP‐FTMW) spectrometers. The experimental structures of (CH2F2)???(H2O)2, (CH2F2)2???(H2O), (CH2F2)???(H2O)3, and (CH2F2)2???(H2O)2 were unambiguously identified with the aid of 18 isotopic substituted species. A subtle competition between hydrogen, halogen, and carbon bonds is observed and a detailed analysis was performed on the complex network of non‐covalent interactions which stabilize each cluster. The study shows that the combination of stabilizing contact networks is able to reinforce the interaction strength through a cooperative effect, which can lead to large stable oligomers. 相似文献
38.
39.
40.