Steric and Electronic Effects on the Heterolytic H(2)-Splitting by Phosphine-Boranes R(3)B/PR ‘(3) (R = C(6)F(5), Ph; R ‘ = C(6)H(2)Me(3), tBu, Ph, C(6)F(5), Me, H): A Computational Study

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	Steric and Electronic Effects on the Heterolytic H(2)-Splitting by Phosphine-Boranes R(3)B/PR ‘(3) (R = C(6)F(5), Ph; R ‘ = C(6)H(2)Me(3), tBu, Ph, C(6)F(5), Me, H): A Computational Study
	Gao, SL ; Wu, W ; Mo, YR
刊名	http://dx.doi.org/10.1002/qua.22901
	2011-11-15
关键词	FRUSTRATED LEWIS PAIRS UNCONVENTIONAL HYDROGEN-BONDS ENERGY DECOMPOSITION ANALYSIS FREE CATALYTIC-HYDROGENATION ACID-BASE COMPLEXES PROTON-TRANSFER METAL-FREE GAS-PHASE AB-INITIO HYDRIDE AFFINITIES
英文摘要	Natural Science Foundation of China [20533020, 20873106]; The steric and electronic effects exerted by the substituents R/R' on the heterolytic H-2-splitting by phosphine-boranes R3B/PR'(3) [R = C6F5 (1), Ph (2); R' = C6H2Me3 (a), tBu (b), Ph (c), C6F5 (d), Me (e), H (f)] have been studied by performing quantum mechanical density functional theory and RI-MP2 calculations. Energy decomposition analyses based on the block-localized wavefunction method show that the nature of the interaction between R3B and PR'(3) is strongly dependent on the B-P distance. With short B-P distances (similar to 2.1 angstrom), the strength of Lewis pairs results from the balance among various energy terms, and both strong and weak dative bonds can be found in this group. However, at long B-P distances (>4.0 angstrom), the correlation and dispersion energy (Delta E-corr) dominates. In other words, the van der Waals (vdW) interaction rules these weakly bound complexes. No ion-pair structures of 1f and 2c-2f can be located as they instantly converge to vdW complexes R3B center dot center dot center dot H-2 center dot center dot center dot PR'(3). We thus propose a model, which predicts that when the sum (E-hp) of the hydride affinity (HA) of BR3 and the proton affinity (PA) of PR'(3) is higher than 340.0 kcal/mol, the ion-pair [R3BH-][HPR'(+)(3)] can be observed, whereas with E-hp below this value, the ion pair would instantly undergo the combination of proton and hydride with the release of H-2. The overall reaction energies (1a-1e and 2a-2b) can be best described by a fitting equation with HA(BR3), PA(PR'(3)), and the binding energy Delta E-b(BR3/PR'(3)) as predictor variables: Delta E-R([R3BH-][HPR'(+)(3)]) = -0.779HA(BR3) - 0.695PA(PR'(3)) - 1.331 Delta E-b(zpe,cp) (BR3/PR'(3)) + 245.3 kcal/mol. The fitting equation provides quantitative insights into the steric and electronic effects on the thermodynamic aspects of the heterolytic H-2-splitting reactions. The electronic effects are reflected by HA(BR3) and PA(PR'(3)), and Delta E-b can be significantly influenced by the steric overcrowding. (C) 2010 Wiley Periodicals, Inc. Int J Quantum Chem 111: 3761-3775, 2011
语种	英语
内容类型	期刊论文
源URL	[http://dspace.xmu.edu.cn/handle/2288/61511]
专题	化学化工－已发表论文
推荐引用方式 GB/T 7714	Gao, SL,Wu, W,Mo, YR. Steric and Electronic Effects on the Heterolytic H(2)-Splitting by Phosphine-Boranes R(3)B/PR ‘(3) (R = C(6)F(5), Ph; R ‘ = C(6)H(2)Me(3), tBu, Ph, C(6)F(5), Me, H): A Computational Study[J]. http://dx.doi.org/10.1002/qua.22901,2011.
APA	Gao, SL,Wu, W,&Mo, YR.(2011).Steric and Electronic Effects on the Heterolytic H(2)-Splitting by Phosphine-Boranes R(3)B/PR ‘(3) (R = C(6)F(5), Ph; R ‘ = C(6)H(2)Me(3), tBu, Ph, C(6)F(5), Me, H): A Computational Study.http://dx.doi.org/10.1002/qua.22901.
MLA	Gao, SL,et al."Steric and Electronic Effects on the Heterolytic H(2)-Splitting by Phosphine-Boranes R(3)B/PR ‘(3) (R = C(6)F(5), Ph; R ‘ = C(6)H(2)Me(3), tBu, Ph, C(6)F(5), Me, H): A Computational Study".http://dx.doi.org/10.1002/qua.22901 (2011).