Potential energy surfaces for low-lying electronic states of SO2

The potential energy surfaces for the nine low-lying electronic states of SO₂ have been constructed by using the multi-reference second order perturbation theory (MRPT2) with the basis set cc-pVTZ. The optimized geometries and the adiabatic excitation energies of these states are in good agreement with experiments and previous calculations. The crossings and avoided crossings displayed in the potential energy surfaces are expounded.     

Properties of alkylbenzimidazoles for CO2 and SO2 capture and comparisons to ionic liquids

To date, few reports have been concerned with the physical properties of the liquid phases of imidazoles and benzimidazoles-potential starting materials for a great number of ionic liquids. Prior research has indicated that alkylimidazole solvents exhibit different, and potentially advantageous physical properties, when compared to corresponding imidazolium-based ionic liquids. Given that even the most fundamental physical properties of alkylimidazole solvents have only recently been reported, there is still a lack of data for other relevant imidazole derivatives, including benzimidazoles. In this work, we have synthesized a series of eight 1-n-alkylbenzimidazoles, with chain lengths ranging from ethyl to dodecyl, all of which exist as neat liquids at ambient temperature. Their densities and viscosities have been determined as functions of both temperature and molecular weight. Alkylbenzimidazoles have been found to exhibit viscosities that are more similar to imidazolium-based ILs than alkylimidazoles, owed to a large contribution to viscosity from the presence of a fused ring system. Solubilities of CO2 and SO2, two species of concern in the emission of coal-fired power generation, were determined for selected alkylbenzimidazoles to understand what effects a fused ring system might have on gas solubility. For both gases, alkylbenzimidazoles were determined to experience physical, non-chemically reactive, interactions. The solubility of CO2 in alkylbenzimidazoles is 10%-30% less than observed for corresponding ILs and alkylimidazoles. 1-butylbenzimidazole was found to readily absorb at least 0.333 gram SO2 per gram at low pressure and ambient temperature, which could be readily desorbed under an N2 flush, a behavior more similar to imidazolium-based ILs than alkylimidazoles. Thus, we find that as solvents for gas separations, benzimidazoles share characteristics with both ILs and alkylimidazoles.     

Multicomponent Reactions Based on SO2 Surrogates: Recent Advances

Compounds containing sulfonyl-derived functional groups have received intensive attention owing to their widespread applications in life science, pharmaceuticals and materials science. To access this type of compounds, the multi-component sulfonylation reactions relying on sulfur dioxide (SO₂) insertion strategy have emerged as novel and attractive approaches in the past decade. The utilization of SO₂ surrogates for SO₂ insertion in the multicomponent reactions (MCRs) have improved reaction flexibility and step economy. Moreover, some advances have been achieved in the challenging but practical asymmetric MCRs for the construction of high value-added chiral sulfones. This review aims to summarize the progress made in the MCRs involving SO₂ surrogates from 2019 to 2022, and point out the potentials and challenges in this field.     

A New Perspective on Li–SO2 Batteries for Rechargeable Systems

Primary Li–SO₂ batteries offer a high energy density in a wide operating temperature range with exceptionally long shelf life and have thus been frequently used in military and aerospace applications. Although these batteries have never been demonstrated as a rechargeable system, herein, we show that the reversible formation of Li₂S₂O₄, the major discharge product of Li–SO₂ battery, is possible with a remarkably smaller charging polarization than that of a Li–O₂ battery without the use of catalysts. The rechargeable Li–SO₂ battery can deliver approximately 5400 mAh g^?1 at 3.1 V, which is slightly higher than the performance of a Li–O₂ battery. In addition, the Li–SO₂ battery can be operated with the aid of a redox mediator, exhibiting an overall polarization of less than 0.3 V, which results in one of the highest energy efficiencies achieved for Li–gas battery systems.     

SO2-4/SnO2催化剂的制备及其对苯硝化反应的催化活性

采用(NH4)2SO4溶液浸渍法制备了一系列SO2-4/SnO2催化剂(Cat-n,n=5,10,15,20),其结构经IR表征.以Cat-10(焙烧温度500℃)催化苯液相硝化反应的研究结果表明,引入SO2-4后催化剂的活性显著增加,硝基苯产率63.8%.     

The potential energy curves of low-lying electronic states of S2O

Potential energy curves (PECs) of the symmetric and asymmetric bent S(2)O molecules are constructed using the configuration-based multireference second order perturbation theory and multireference configuration interaction with single and double excitations. Based on the PECs, the equilibrium structures of the ground state and several low-lying excited states, as well as the vertical and adiabatic transition energies, are obtained. Furthermore, avoided crossings and intersections displayed on the PECs are studied. The dissociation of states for the asymmetric bent S(2)O, especially the predissociative of the excited (~)C1A' state, is also discussed in detail. According to our calculations, the predissociation limit of (~)C1A' is found to be located in the vicinity of 2(6) or 2(5) (reckoning in the zero-point energy revision) S-S stretching vibration level, which is in good agreement with the available experimental data.     

Potential energy surfaces for OsH2

Summary We compute the potential energy surfaces of 12 electronic states of OsH₂ (four quintet, four triplet, and four singlet) arising from⁵ D ground state of the Os atom as well as triplet and singlet excited states using the complete active space multiconfiguration self-consistent field (CAS-MCSCF) followed by multireference configuration interaction (MRCI) and relativistic CI (RCI) calculation which include up to 430,000 configurations. We find that the⁵ D ground state of Os atom does not insert into H₂ while the excited³ F state of Os does. The³ B ₁ ground state of OsH₂ (there are two other nearly degenerate states) in the absence of spin-orbit coupling was found to be 22 kcal/mol more stable than Os(⁵ D)+H₂. The spin-orbit mixing of³ B ₁,³ B ₂,³ A ₂, and¹ A ₁ states was so strong that it induces significant change in bond angles (up to 10°) for OsH₂.Dedicated to Prof. Klaus RuedenbergCamille and Henry Dreyfus Teacher-Scholar     

Potential energy surfaces for BeH2 and BH2

The diatomics-in-molecules method has been used to obtain potential energy surfaces (PES) for the molecules BeH₂ and BH₂. The method is used in a way proposed by Tully [1]. The present paper contains an analysis of some features of PES in the vicinity of their crossing near linear configurations of the molecules.     

Al2（SO4）3／SiO2催化甲醇脱水合成二甲醚

采用浸渍法制备了不同负载量的Al2（SO4）3／SiO2催化剂．使用BET、XRD、FT—IR、异丙醇探针反应、NH3吸附量热和NH3吸附红外等手段对催化剂进行了表征,并测试了其在甲醇脱水合成二甲醚反应中的活性．BET、XRD和FT-IR结果表明,载体SiO2的表面积较高,随着Al2（SO4）3负载量的增加,样品的表面积逐渐降低,当Al2（SO4）3负载量高于20％时,样品表面开始出现晶相Al2（SO4）3．NH3吸附量热和NH3吸附红外结果表明,载体SiO2的酸性很弱,负载了Al2（SO4）3后,样品酸性大大增强,且酸性随着Al2（SO4）3负载量的增加先增强后减弱．样品表面同时存在B酸中心和L酸中心,但以B酸中心为主．Al2（SO4）3负载量为3％的样品的表面酸性最强,因而在甲醇脱水反应中表现出最高的反应活性,533K,甲醇转化率为83．5％,二甲醚选择性100％．     

Rotation–vibration energy levels from recent potential energy surfaces for the ground electronic states of NO2 and H2O

Using recently published potential energy surfaces, rovibrational energy levels are computed for the ground electronic states of H₂O and NO₂, using three‐dimensional discrete variable representation (DVR) algorithms. Calculations are presented for H₂O to demonstrate the accuracy of these algorithms. In the case of NO₂, comparisons with previous calculations are made as a test for the accuracy of the new potential energy surface. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 76: 535–540, 2000     

Theoretical study on potential energy curves and spectroscopy properties of ground and low-lying excited electronic states of BrCl~

The calculations on the potential energy curves and spectroscopic constants of the ground and low-lying excited states of BrCl ,one of the important molecular ions in environment science,have been performed by using the multireference configuration interaction method at high level of theory in quantum chemistry.Through analyses of the effects of the spin-orbit coupling interaction on the elec-tronic structures and spectroscopic properties,the multiconfiguration characteristic of the X2Π ground state and low-lying excited states was established.The spin-orbit coupling splitting energy of the X2 Π ground state was calculated to be 1814 cm-1,close to the experimental value 2070 cm-1.The spin-orbit coupling splitting energy of the 2Π(Ⅱ) exited state was predicted to be 766 cm-1.The transition dipole moments and Frank-Condon factors of the 3/2(Ⅲ)-X3/2 and 1/2(Ⅲ)-1/2(I) transitions were estimated,and the radiative lifetimes of the two transitions were briefly discussed.     

Ab initio calculation of the potential surfaces for low-lying valence electronic states of the C2H radical

The results of an extensive CI treatment for the three lowest-lying electronic states 1² A′, 2² A′ and 1² A″ of C₂H are reported. Two-dimensional C-C stretching/bending potential surfaces for these species are calculated. Electronic dipole and transition moments are computed as a function of the bond angle and the C-C bond length. The results serve as a starting point in a theoretical analysis of the rovibronic structure of the long-wavelength spectra of C₂H.     

Ni(100)表面吸附SO2的密度泛函研究

以原子簇Ni14为模拟表面,采用DFT/B3LYP方法研究了二氧化硫(SO2)分子在Ni(100)表面的吸附构型、能量、电荷及态密度。结果表明,SO2分子通过S原子平铺吸附在Ni(100)的桥位最有利,计算结果与实验相符。电荷密度及态密度分析表明,Ni原子的d轨道与SO2分子的空p轨道之间存在明显的s-p作用和电荷转移,这一作用可能导致SO2分子发生解离。     

配合物Zn(His)SO4·H2O(s)的低温热容和热力学性质

通过精密自动绝热热量计测定了配合物Zn(His)SO4*H2O(s)在78～390K温区的摩尔热容,由热容曲线得到其起始脱水温度328.90K;用最小二乘法拟合得到摩尔热容(Cp,m)对温度(T)的多项式方程,并在此基础上计算了它的各种热力学函数.此外,研究了其在惰性气氛下的热分解过程.     

Potential energy surface and thermochemistry for the direct gas phase reaction of germane and water

Gas phase reaction between germane GeH₄ and water H₂O was investigated at CCSD(T)/[aug-cc-pVTZ-pp for Ge + Lanl2dz for H and O]//MP2/6-31G(d,p) level. Only the hydrogen elimination channels are monitored. Within the energy range of 100 kcal/mol, we located nine equilibrium and six transition states on the potential energy surface (PES) of the Ge–O–H systems. GeH₄ reacts with H₂O exothermically (by 2.37 kcal/mol) without a barrier to form a non-planar complex GeH₄·H₂O which isomerizes to GeH₃OH·H₂ and H₂GeOH₂·H₂ with a barrier of 44.34 kcal/mol and 53.75 kcal/mol respectively. The first step of hydrogen elimination gives two non-planar species, GeH₃OH and H₂GeOH₂ but germinol GeH₃OH is found to be more stable. Further thermal decomposition reactions of GeH₃OH involving hydrogen elimination have been studied extensively using the same method. The final hydrogen elimination step gives HGeOH which can exist in cis and trans forms. As the trans form is more stable, only the trans form is considered on the potential energy surface (PES) of the reaction. The important thermochemical parameters (∆_rE_tot + ZPE), ∆_rH and ∆_rG for the H₂ elimination pathways are predicted accurately.     

活性炭脱除低浓度二氧化硫的研究进展

用活性炭脱除低浓度的二氧化硫是一种经济有效的方法,文章综述了近年来国内外在此方面的研究进展。归纳了反应机理,总结了活性炭的孔道结构、表面化学环境、改性剂、原料气的湿度、温度和原料气的组分对反应的影响,以及失活后的活性炭的再生方法,并对这种脱硫方法的应用前景进行了探讨。     

Potential energy curves and spectral properties for electronic states of F2 and F+2

Potential energy (PE) curves for the Rydberg states of F₂, and for the ground and lowest two electronic states each of symmetry ²Π_g,u, ²Δ_g,u and ²Σ^±_g,u of F⁺₂, have been obtained using modest-sized configuration-interaction calculations. These PE curves have been used to calculate spectroscopic constants for the electronic states and the results agree reasonably well with the limited experimental and theoretical results previously reported. The theoretical PE curves for the Rydberg states of F₂ are found to be strongly perturbed by valence-Rydberg-ionic interactions and these perturbations appear to be responsible for certain features in recently reported electron energy-loss spectra in F₂. The corresponding electronic wavefunctions have been used to calculate the electronic transition moment, as a function of the internuclear distance, for dipole-allowed transitions between the lowest excited electron state of each symmetry and the appropriate ground electronic state. The radiative emission probabilities, natural lifetimes, and absorption oscillator strengths, for each band system, are also reported here. The predicted lifetimes for vibrational levels of the A ²Π_u of electronic state in F⁺₂ vary from 1.3–1.5 μs and agree reasonably well with the single available set of measurements. The predicted radiative lifetimes for the higher electronic states of F⁺₂ are substantially longer and fall into the range 5–100 ms.