We investigate the transition-state (TS) region of the potential energy surface (PES) of the reaction tBu3P + H2 + B(C6F5)3 → tBu3P-H(+) + (-)H-B(C6F5)3 and the dynamics of the TS passage at room temperature. Owing to the conformational inertia of the phosphane⋅⋅⋅borane pocket involving heavy tBu3P and B(C6F5)3 species and features of the PES E(P⋅⋅⋅H, B⋅⋅⋅H | B⋅⋅⋅P) as a function of P⋅⋅⋅H, B⋅⋅⋅H, and B⋅⋅⋅P distances, a typical reactive scenario for this reaction is a trajectory that is trapped in the TS region for a period of time (about 350 fs on average across all calculated trajectories) in a quasi-bound state (scattering resonance). The relationship between the timescale of the TS passage and the effective conformational inertia of the phosphane⋅⋅⋅borane pocket leads to a prediction that isotopically heavier Lewis base/Lewis acid pairs and normal counterparts could give measurably different reaction rates. Herein, the predicted quasi-bound state could be verified in molecular collision experiments involving femtosecond spectroscopy.
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http://dx.doi.org/10.1002/cphc.201402450 | DOI Listing |
Chem Commun (Camb)
May 2023
Institute of Drug Discovery Technology, Ningbo University, Ningbo 315211, Zhejiang, China.
Reactions of (BuOCN) with FLPs are examined. B(CF) interacts with the carbonyl oxygen atoms inducing loss of CHCMe; however, in the presence of basic donors, the protons are intercepted affording the salts [Hbase] [((CF)BOCN)] (base = BuP 1, NCHPh2, HNCHMe3). In contrast, in the presence of (-Tol)P, a proton transfers to the diazo-N atom affording (-Tol)PN(COBu)NHB(CF)4.
View Article and Find Full Text PDFPhys Chem Chem Phys
June 2021
School of Environment and Safety Engineering, North University of China, Taiyuan, 030051, P. R. China.
Sterically hindered frustrated Lewis pairs (FLPs) have the ability to activate hydrogen molecules, and their reactivity is strongly determined by the geometric parameters of the Lewis acids and bases. A recent experimental study showed that ionic liquids (ILs) could largely improve the effective configuration of FLPs. However, the detailed mechanistic profile is still unclear.
View Article and Find Full Text PDFInorg Chem
June 2019
Departamento de Química Orgánica I and Centro de Innovación en Química Avanzada, Facultad de Ciencias Químicas , Universidad Complutense de Madrid , Madrid 28040 , Spain.
The role of carbones (CL; L = phosphines vs carbenes) as Lewis bases in dihydrogen (H) activation reactions in the presence of the Lewis acid B(CF) has been computationally explored by means of density functional theory calculations. To this end, the interaction between H and the [carbone···B(CF)] pair along the reaction coordinate has been quantitatively analyzed in detail and compared to the parent [ BuP···B(CF)] frustrated Lewis pair. In addition, the influence on the reactivity of both the nature of the central E atom and the surrounding ligands in ylidones (EL) has also been considered.
View Article and Find Full Text PDFJ Phys Chem A
September 2018
Department of Organic Chemistry , Stockholm University, Stockholm 10691 , Sweden.
Knowing that the Papai's electron transfer (ET) and the Grimme's electric field (EF) models draw attention to somewhat different physical aspects, we are going to systematically (re)examine interactions in the transition states (TSs) of the heterolytic H-cleavage by the Frustrated Lewis Pairs (FLPs). Our main vehicle is the quantitative energy decomposition analysis (EDA), a powerful method for elucidation of interactions, plus the analysis of molecular orbitals (MOs). Herein, the Lewis acid (LA) is B(CF) and the Lewis bases (LBs) are tBuP, ( o-CHMe)P, 2,6-lutidine, 2,4,6-lutidine, MeN═C(Ph)Me imine, MeN(H)-C(H)PhMe amine, THF, 1,4-dioxane, and acetone.
View Article and Find Full Text PDFChem Sci
April 2017
Department of Chemistry , University of Toronto, 80 St. George St. , Toronto , Ontario M5S 3H6 , Canada . Email:
A microfluidic strategy has been used for the time- and labour-efficient evaluation of the relative efficiency and thermodynamic parameters of CO binding by three Lewis acid/base combinations, where efficiency is based on the amount of CO taken up per binding unit in solution. Neither BuP nor B(CF) were independently effective at CO capture, and the combination of the imidazolin-2-ylidenamino-substituted phosphine (NIPr)P and B(CF) was equally ineffective. Nonetheless, an archetypal frustrated Lewis pair (FLP) comprised of BuP and B(CF) was shown to bind CO more efficiently than either the FLP derived from tetramethylpiperidine (TMP) and B(CF) or the highly basic phosphine (NIPr)P.
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