A set of d-polarization functions for pseudo-potential basis sets of the main group elements AlBi and f-type polarization functions for Zn, Cd, Hg

Höllwarth, A.; Böhme, Marlis; Dapprich, Stefan; Ehlers, Andreas W.; Gobbi, A.; Jonas, Volker; Köhler, Klaus; Stegmann, Ralf; Veldkamp, Achim; Frenking, Gernot

doi:10.1016/0009-2614(93)89068-s

Cited by 908 publications

(765 citation statements)

References 6 publications

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“…The 6-31G(d) basis set was used for C, H, O, and N atoms; the LANL2DZ basis set together with the associated effective core potential (ECP) was utilized for Si and Y atoms [54]. One d-polarization function (exponent of 0.284) was augmented for the basis set of Si atoms [55]. Such a computational strategy has been widely used for the study of transition metal-containing systems [56][57][58][59][60][61].…”

Section: Computational Detailsmentioning

confidence: 99%

Computational Studies on the Selective Polymerization of Lactide Catalyzed by Bifunctional Yttrium NHC Catalyst

et al. 2017

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Abstract:A theoretical investigation of the ring-opening polymerization (ROP) mechanism of rac-lactide (LA) with an yttrium complex featuring a N-heterocyclic carbine (NHC) tethered moiety is reported. It was found that the carbonyl of lactide is attacked by N(SiMe 3 ) 2 group rather than NHC species at the chain initiation step. The polymerization selectivity was further investigated via two consecutive insertions of lactide monomer molecules. The insertion of the second monomer in different assembly modes indicated that the steric interactions between the last enchained monomer unit and the incoming monomer together with the repulsion between the incoming monomer and the ligand framework are the primary factors determining the stereoselectivity. The interaction energy between the monomer and the metal center could also play an important role in the stereocontrol.

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Section: Computational Detailsmentioning

confidence: 99%

Computational Studies on the Selective Polymerization of Lactide Catalyzed by Bifunctional Yttrium NHC Catalyst

et al. 2017

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“…For the spectator hydrogen atoms, we used a smaller splitvalence 3-21G 26 basis set. The valence basis set for the tin atom was augmented with a set of five d polarization functions, with an exponential coefficient of 0.180 27 Figure 1) were characterized as minima or transition state through harmonic vibrational frequency calculations. The calculated harmonic frequencies were also used to compute the entropy contribution to the energy variation.…”

Section: Methods Of Calculationmentioning

confidence: 99%

On the cis -> trans isomerization of the square-planar [Pt(Cl)(SnCl3)(PH3)2] compound: ab initio gas phase reaction mechanism and solvent effects using continuum models

Rocha¹,

Almeida²

2000

J. Braz. Chem. Soc.

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A isomerização cis → trans do composto quadrático plano d 8 [Pt(Cl)(SnCl 3 )(PH 3 ) 2 ] foi investigada utilizando-se o nível ab initio de cálculo MP4(SDQ)//MP2. As estruturas otimizadas, localizadas na superfície de energia potencial em fase gasosa, indicam que esta reação se processa através de um estado de transição quase-tetraédrico. A influência dos efeitos eletrônicos dos ligantes no mecanismo da reação foi investigada utilizando-se o método de Análise de Decomposição de Carga (CDA), o qual forneceu suporte para a compreensão do forte efeito trans do ligante SnCl 3 . O efeito devido ao solvente na energia de reação em fase gasosa foi avaliado utilizando-se os modelos contínuos SCRF e IPCM. Em ambos os casos um aumento na barreira de energia para o processo foi observado, sendo que a estabilidade termodinâmica dos isômeros cis e trans foi alterada pela solvatação.The cis → trans isomerization of the d 8 square planar [Pt(Cl)(SnCl 3 )(PH 3 ) 2 ] compound was investigated at the MP4(SDQ)//MP2 level of theory. The optimized structures located on the gasphase potential energy surface indicate that this reaction proceeds through a quasi-tetrahedral transition state. The influence of electronic effects of the ligands on the reaction mechanism was investigated with the Charge Decomposition Analysis (CDA) method, which gave support to understand the strong trans effect of the SnCl 3 ligand. The solvent effect on the gas phase energy reaction was evaluated using the SCRF and IPCM continuum models. In both cases, an increase on the energy barrier for the process was observed and, the thermodynamical stability of the cis and trans isomers was changed upon solvation.

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“…在优化构型的基础上 , 采用 M06/GEN1 方法和 SMD [31] 模型计算各化合物的液相单点能量(GEN1: 6-311＋＋G*/ for C, H, O, N, P and Si; SDD for Ir), (氯苯与 Brookhart 实验中使用的 5-氘代氯苯极性相同, 因此采用氯苯作为溶剂). 对 Ir 添加极化函数 [ζ(f)＝0.938] [32,33] . 本文中所有的能量均为气相自由能校正和液相单点能之和.…”

Section: 运用 M06unclassified

Hydride Source in Ethers Hydrosilylation Reaction Catalyzed by Brookhart's Ir(Ⅲ) Pincer Complex

张琦¹,

刘奥²,

于海珠³

et al. 2018

Acta Chim. Sinica

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The hydrosilylative reduction with silane is a popular defunctionalization strategy to convert biomass into chemicals and energies because of the mild reaction conditions. Among these, the reduction of C-O bond is particularly important because of its application in sugar biomass reduction. The (C 6 F 5 ) 3 B/silane catalytic system has been frequently used in the reduction of C-O bonds in the past years. However, Brookhart et al. reported alkyl ethers reduction by using Ir(III) pincer catalyst and reductant HSiEt 3 . This work provides a novel hydrosilylation catalyst for C-O reduction and an effective method for sugar biomass deoxygenation. According to the previous mechanistic proposals on similar Ir catalysed hydrosilylation reactions, the iridium dihydride complex, iridium silyl hydride complex, silane adduct iridium complex and iridium silyl trihydride complex might possibly act as the hydride source. We carried out the theoretical study on Brookhart's Ir(III) Pincer Complex/HSiEt 3 catalyzed hydrosilylation reaction of EtOEt yielding ethane and EtOSiEt 3 . The density functional theory (DFT) calculations in our study indicate that the iridium dihydride complex is the best hydride source. Our calculation result is consistent well with experimental observations in Brookhart's experiment. For example, the phenomenon that adding iridium dihydride complex into the reaction system increases the reaction rate is understandable because the complex is involved in the rate-determining step. From the Distortion/Interaction analysis, we found that hydride transfer steps on the other three possible hydride sources are disfavoured by the HSiEt 3 /-SiEt 3 group (derived from HSiEt 3 ) bonded with Ir center. The iridium silyl hydride complex is unfavourable because the Ir-H bond is strengthened and the pincer ligand is distorted. For the silane adduct iridium complex, the coordination of HSiEt 3 destabilizes iridium complex intermediate for entropy increases and trans effect, and destabilizes the related transition state by damaging its pincer ligand. Further, the corresponding hydride transfer transition state from iridium silyl trihydride is highly unstable and Si-H bond always reform automatically. What's more important, the moderate bond dissociation energy of Ir-hydride, small steric hindrance and the promotion effect of SiEt 3 group coordination with ether all facilitate the hydride transfer on the iridium dihydride complex.

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A set of d-polarization functions for pseudo-potential basis sets of the main group elements AlBi and f-type polarization functions for Zn, Cd, Hg

Cited by 908 publications

References 6 publications

Computational Studies on the Selective Polymerization of Lactide Catalyzed by Bifunctional Yttrium NHC Catalyst

Computational Studies on the Selective Polymerization of Lactide Catalyzed by Bifunctional Yttrium NHC Catalyst

On the cis -> trans isomerization of the square-planar [Pt(Cl)(SnCl3)(PH3)2] compound: ab initio gas phase reaction mechanism and solvent effects using continuum models

Hydride Source in Ethers Hydrosilylation Reaction Catalyzed by Brookhart's Ir(Ⅲ) Pincer Complex

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