1
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Kalita P, Medhi B, Singh HK, Bhattacharyya HP, Gupt N, Sarma M. Perturbing π-clouds with Substituents to Study the Effects on Reaction Dynamics of gauche-1,3-Butadiene to Bicyclobutane Electrocyclization. Chemphyschem 2023; 24:e202200727. [PMID: 36281900 DOI: 10.1002/cphc.202200727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Revised: 10/23/2022] [Indexed: 02/03/2023]
Abstract
The conical intersection (CI) governs the ultra-fast relaxation of excited states in a radiationless manner and are observed mainly in photochemical processes. In the current work, we investigated the effects of substituents on the reaction dynamics for the conversion of gauche-1,3-butadiene to bicyclobutane via photochemical electrocyclization. We incorporated both electron withdrawing (-F) and donating (-CH3 ) groups in the conjugated system. In our study, we optimized the minimum energy conical intersection (MECI) geometries using the multi-configurational state-averaged CASSCF approach, whereas, to study the ground state reaction pathways for the substituted derivatives, dispersion corrected, B3LYP-D3 functional was used. The non-adiabatic surface hopping molecular dynamics simulations were performed to observe the behaviour of electronic states involved throughout the photoconversion process. The results obtained from the multi-reference second-order perturbation correction of energy at the XMS-CASPT2 level of theory, topography analysis, and non-adiabatic dynamics suggest that the -CH3 substituted derivatives can undergo faster thermal conversion to the product in the ground state with a smaller activation energy barrier compared to -F substituted derivative. Our study also reveals that the GBUT to BIBUT conversion follows both conrotatory and disrotatory pathways, whereas, on substitution with -F or -CH3 , the conversion proceeds via the conrotatory pathway.
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Affiliation(s)
- Papu Kalita
- Department of Chemistry, Indian Institute of Technology Guwahati, Assam, 781039, Indian
| | - Biman Medhi
- Department of Chemistry, Indian Institute of Technology Guwahati, Assam, 781039, Indian
| | - Haobam Kisan Singh
- Department of Chemistry, Indian Institute of Technology Guwahati, Assam, 781039, Indian
| | | | - Nikhil Gupt
- Department of Chemistry, Indian Institute of Technology Guwahati, Assam, 781039, Indian.,Current Address: Indian Institute of Technology Kanpur, Uttar Pradesh, 208016, Indian
| | - Manabendra Sarma
- Department of Chemistry, Indian Institute of Technology Guwahati, Assam, 781039, Indian
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2
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Unexpected formation of 2-methyl-1H-naphtho [2, 3-d] imidazole via decarboxylation governed mechanistic pathway. Chem Phys 2023. [DOI: 10.1016/j.chemphys.2022.111735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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3
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Nunes CM, Roque JP, Doddipatla S, Wood SA, McMahon RJ, Fausto R. Simultaneous Tunneling Control in Conformer-Specific Reactions. J Am Chem Soc 2022; 144:20866-20874. [PMID: 36321916 PMCID: PMC9776521 DOI: 10.1021/jacs.2c09026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We present here a new example of chemical reactivity governed by quantum tunneling, which also highlights the limitations of the classical theories. The syn and anti conformers of a triplet 2-formylphenylnitrene, generated in a nitrogen matrix, were found to spontaneously rearrange to the corresponding 2,1-benzisoxazole and imino-ketene, respectively. The kinetics of both transformations were measured at 10 and 20 K and found to be temperature-independent, providing clear evidence of concomitant tunneling reactions (heavy-atom and H-atom). Computations confirm the existence of these tunneling reaction pathways. Although the energy barrier between the nitrene conformers is lower than any of the observed reactions, no conformational interconversion was observed. These results demonstrate an unprecedented case of simultaneous tunneling control in conformer-specific reactions of the same chemical species. The product outcome is impossible to be rationalized by the conventional kinetic or thermodynamic control.
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Affiliation(s)
- Cláudio M. Nunes
- University
of Coimbra, CQC-IMS, Department of Chemistry, 3004-535 Coimbra, Portugal,
| | - José P.
L. Roque
- University
of Coimbra, CQC-IMS, Department of Chemistry, 3004-535 Coimbra, Portugal
| | - Srinivas Doddipatla
- University
of Coimbra, CQC-IMS, Department of Chemistry, 3004-535 Coimbra, Portugal
| | - Samuel A. Wood
- Department
of Chemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706-1322, United States
| | - Robert J. McMahon
- Department
of Chemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706-1322, United States
| | - Rui Fausto
- University
of Coimbra, CQC-IMS, Department of Chemistry, 3004-535 Coimbra, Portugal
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4
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Chakraborty B, Jha R, Kar S, Chattaraj PK. Controlling Tunneling Oscillation and Quantum Localization in an Asymmetric Double-Well Potential: A Bohmian Perspective. J Phys Chem A 2022; 126:4834-4847. [PMID: 35834735 DOI: 10.1021/acs.jpca.2c03049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The roles of spatial symmetry and strength of external time-dependent perturbation on the dynamics of a quantum particle, initially localized in one of the wells of an asymmetric double-well potential are studied using the recently developed techniques incorporating quantum theory of motion and time-dependent Fourier grid Hamiltonian methods. The model used here includes a mimic of the related experimental situations which is considered as a perturbation to the static double-well potential. Analysis of localized and delocalized phase space structures and corresponding time-profile of tunneling probability reveal the recipe toward controlling the tunneling oscillations by modulating the parameters of applied perturbation. A study on a stochastic pulsating potential also reveals the root to the quantum localization, even in moderate field strength.
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Affiliation(s)
- Bhrigu Chakraborty
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Ruchi Jha
- Advanced Technology Development Centre, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Susmita Kar
- Department of Chemistry, Scottish Church College, Kolkata 700006, India
| | - Pratim Kumar Chattaraj
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
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5
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Greer EM, Siev V, Segal A, Greer A, Doubleday C. Computational Evidence for Tunneling and a Hidden Intermediate in the Biosynthesis of Tetrahydrocannabinol. J Am Chem Soc 2022; 144:7646-7656. [PMID: 35451301 DOI: 10.1021/jacs.1c11981] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Quantum tunneling is computed for a reaction sequence that models the conversion of the ortho-quinone methide of cannabigerolic acid 1 to the decarboxylated product (-)-trans-Δ9-tetrahydrocannabinol (THC, 3). This calculation is the first to evaluate multidimensional tunneling in this sequence. Computations were carried out with POLYRATE and GAUSSRATE using B3LYP/6-31G(d,p) to examine the mechanism of THC 3 formation. The pentyl chain on THC 3 and its precursors were replaced with a methyl group to compute tunneling contributions to the rates of four separate steps: (i) initial Diels-Alder reaction of the quinone methide with the trisubstituted alkene end-group of the geranyl 1Z-CH3 to give 2Z-CH3, (ii) acid-catalyzed keto-enol tautomerization, which converts 2rZ-CH3 to 4rZ-CH3, (iii) carboxyl rotamerization converting 4rZ-CH3 to 4E-CH3, and (iv) decarboxylation that converts 4E-CH3 to 3-CH3. Tunneling contributions to the rate constants of steps (i)-(iv) are between 19 and 76% at 293 K. In step (ii), nonuniform changes in the zero-point vibrational energy along the reaction path created a shallow minimum in the 0 K free energy. It is a hidden intermediate because it is not a minimum on the potential energy surface and is detectable only when zero-point energy is taken into account along the reaction path. Predicted kinetic isotope effects would be experimentally observable at temperatures that are convenient to use. This is particularly relevant in the decarboxylation stage of the reaction sequence and has important implications because of its role in THC 3 formation.
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Affiliation(s)
- Edyta M Greer
- Department of Natural Sciences, Baruch College of the City University of New York, 17 Lexington Avenue, New York, New York 10010, United States
| | - Victor Siev
- Department of Natural Sciences, Baruch College of the City University of New York, 17 Lexington Avenue, New York, New York 10010, United States
| | - Ayelet Segal
- Department of Natural Sciences, Baruch College of the City University of New York, 17 Lexington Avenue, New York, New York 10010, United States
| | - Alexander Greer
- Department of Chemistry and Graduate Center, Brooklyn College of the City University of New York, 2900 Bedford Avenue, Brooklyn, New York 11210, United States.,PhD Program in Chemistry, The Graduate Center of the City University of New York, New York, New York 10016, United States
| | - Charles Doubleday
- Department of Chemistry, Columbia University, 3000 Broadway, MC 3142, New York, New York 10027, United States
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6
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Bettens T, Eeckhoudt J, Hoffmann M, Alonso M, Geerlings P, Dreuw A, De Proft F. Designing Force Probes Based on Reversible 6π-Electrocyclizations in Polyenes Using Quantum Chemical Calculations. J Org Chem 2021; 86:7477-7489. [PMID: 33988028 DOI: 10.1021/acs.joc.1c00482] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The conjugated π-system in polyenes can be interrupted by electrocyclic ring-closure reactions. In this work, this 6π-electrocylization is shown by means of density functional calculations to be reversible by the application of an external mechanical pulling force at the terminal ends of the interrupted polyene chain. The test systems were constrained in a fused ring system, thus locking the orientation of three π-bonds and generally promoting 6π-electrocyclic ring-closure reactions. For several systems, the forward reaction is exergonic and the corresponding reaction barrier is comparable to those reported in the literature. The reverse reaction is triggered by an external pulling force of 2 nN (nano-Newton) or less and also becomes exergonic in all investigated polyenes under these force conditions. Moreover, it proceeds via a low reaction barrier when a pulling force of 2 nN is active, indicating that the mechanical force is an efficient stimulus for triggering ring-opening reactions. Analysis of the strain energy induced by this mechanical force confirms an optimal activation of the corresponding C-C σ-bond that breaks upon ring opening when the pulling positions are located on the polyene chain.
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Affiliation(s)
- Tom Bettens
- Eenheid Algemene Chemie (ALGC), Vrije Universiteit Brussel (VUB), Pleinlaan 2, 1050 Brussels, Belgium
| | - Jochen Eeckhoudt
- Eenheid Algemene Chemie (ALGC), Vrije Universiteit Brussel (VUB), Pleinlaan 2, 1050 Brussels, Belgium
| | - Marvin Hoffmann
- Interdisciplinary Center for Scientific Computing, Ruprecht-Karls University, Im Neuenheimer Feld 205A, D-69120 Heidelberg, Germany
| | - Mercedes Alonso
- Eenheid Algemene Chemie (ALGC), Vrije Universiteit Brussel (VUB), Pleinlaan 2, 1050 Brussels, Belgium
| | - Paul Geerlings
- Eenheid Algemene Chemie (ALGC), Vrije Universiteit Brussel (VUB), Pleinlaan 2, 1050 Brussels, Belgium
| | - Andreas Dreuw
- Interdisciplinary Center for Scientific Computing, Ruprecht-Karls University, Im Neuenheimer Feld 205A, D-69120 Heidelberg, Germany
| | - Frank De Proft
- Eenheid Algemene Chemie (ALGC), Vrije Universiteit Brussel (VUB), Pleinlaan 2, 1050 Brussels, Belgium
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7
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Jabeen F, Kumar A, Rajakumar B. Kinetics, thermochemistry and atmospheric implications for the reaction of OH radicals with CH3CF = CF2 (HFO-1243yc). Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2020.137933] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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8
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9
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Burd TAH, Shan X, Clary DC. Hydrogen tunnelling in the rearrangements of carbenes: the role of dynamical calculations. Phys Chem Chem Phys 2020; 22:962-965. [DOI: 10.1039/c9cp06300e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A tunnelling controlled reaction is studied with semiclassical transition state theory, rationalising the results of experiment.
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Affiliation(s)
- Timothy A. H. Burd
- Physical and Theoretical Chemical Laboratory
- University of Oxford
- Oxford
- UK
| | - Xiao Shan
- Physical and Theoretical Chemical Laboratory
- University of Oxford
- Oxford
- UK
| | - David C. Clary
- Physical and Theoretical Chemical Laboratory
- University of Oxford
- Oxford
- UK
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10
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Jestilä JS, Iker Z, Ryding MJO, Uggerud E. The unimolecular dissociation of magnesium chloride squarate (ClMgC 4O 4−) and reductive cyclooligomerisation of CO on magnesium. Org Biomol Chem 2020; 18:9499-9510. [DOI: 10.1039/d0ob01994a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cyclooligomerisation to squarate is initiated by the coupling of two CO units in MgCl−.
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Affiliation(s)
- Joakim S. Jestilä
- Department of Chemistry and Hylleraas Centre for Quantum Molecular Sciences
- University of Oslo
- Blindern
- Norway
| | - Zsuzsanna Iker
- Budapest University of Technology and Economics
- Department of Organic Chemistry and Technology
- Budapest
- Hungary
| | - Mauritz J. O. Ryding
- Department of Chemistry and Hylleraas Centre for Quantum Molecular Sciences
- University of Oslo
- Blindern
- Norway
| | - Einar Uggerud
- Department of Chemistry and Hylleraas Centre for Quantum Molecular Sciences
- University of Oslo
- Blindern
- Norway
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11
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Ali SY, Reddy KD, Manna AK. Structural, Electronic, and Spectral Properties of Metal Dimethylglyoximato [M(DMG) 2; M = Ni 2+, Cu 2+] Complexes: A Comparative Theoretical Study. J Phys Chem A 2019; 123:9166-9174. [PMID: 31599589 DOI: 10.1021/acs.jpca.9b06762] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Dimethylglyoxime (DMG) usually forms thermodynamically stable chelating complexes with selective divalent transition-metal ions. Electronic and spectral properties of metal-DMG complexes are highly dependent on the nature of metal ions. Using range-separated hybrid functional augmented with dispersion corrections within density functional theory (DFT) and time-dependent DFT, we present a detailed and comprehensive study on structural, electronic, and spectral (both IR and UV-vis) properties of M(DMG)2 [M = Ni2+, Cu2+] complexes. Ni(DMG)2 results are thoroughly compared with Cu(DMG)2 and also against available experimental data. Stronger H-bonding leads to greater stability of Ni(DMG)2 with respect to isolated ions (M2+ and DMG-) compared to Cu(DMG)2. In contrast, a relatively larger reaction enthalpy for Cu(DMG)2 formation from chemically relevant species is found than that of Ni(DMG)2 because of the greater binding enthalpy of [Ni(H2O)6]2+ than that of [Cu(H2O)6]2+. In dimers, Ni(DMG)2 is found to be 6 kcal mol-1 more stable than Cu(DMG)2 due to a greater extent of dispersive interactions. Interestingly, a modest ferromagnetic coupling (588 cm-1) is predicted between two spin-1/2 Cu2+ ions present in the Cu(DMG)2 dimer. Additionally, the potential energy curves calculated along the O-H bond coordinate for both complexes suggest asymmetry and symmetry in the H-bonding interactions between the H-bond donor and acceptor O centers in the solid-state and in solution, respectively, well corroborating with early experimental findings. Interestingly, a lower proton transfer barrier is obtained for the Ni(DMG)2 compared to its Cu-analogue due to stronger H-bonding in the former complex. In fact, relatively weaker H-bonding in Cu(DMG)2 results in blue-shifted O-H stretching modes compared to that in Ni(DMG)2. On the other hand, qualitatively similar optical absorption spectra are obtained for both complexes with red-shifted peaks found for the Cu(DMG)2. Finally, computational models for axial mono- and diligand (aqua and ammonia) coordinated M(DMG)2 complexes are predicted to be energetically feasible and stable with relatively greater binding stability obtained for the ammonia-coordination.
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Affiliation(s)
- Syed Yunus Ali
- Department of Chemistry , Indian Institute of Technology Tirupati , Tirupati , Andhra Pradesh 517506 , India
| | - Kambham Devendra Reddy
- Department of Chemistry , Indian Institute of Technology Tirupati , Tirupati , Andhra Pradesh 517506 , India
| | - Arun K Manna
- Department of Chemistry , Indian Institute of Technology Tirupati , Tirupati , Andhra Pradesh 517506 , India
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12
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Saima B, Wang YA, Hussain R, Muhammad S, Ayub K. Thermal decomposition of syn- and anti-dihydropyrenes; functional group-dependent decomposition pathway. J Mol Model 2019; 25:215. [PMID: 31292739 DOI: 10.1007/s00894-019-4052-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 04/24/2019] [Indexed: 10/26/2022]
Abstract
Syn and anti dihydropyrene (DHP) are excellent thermochromes, and therefore extensively studied for their thermochromic and photochromic properties, respectively. However, they suffer from thermal decomposition due to thermal instability. In this study, we thoroughly investigated pathways for the thermal decomposition of anti- and syn- dihydropyrenes through computational methods. The decomposition pathways include sigmatropic shift and hemolytic and heterolytic (cationic and anionic) cleavages. The decomposition pathway is influenced not only by the dihydropyrene (syn- or anti-) but also by the functional groups present. For anti-dihydropyrenes, sigmatropic shift is the most plausible pathways for CN and CHO internal groups. The cascade of sigmatropic shifts is followed by elimination to deliver substituted pyrenes. For CH3- and H- dihydropyrenes, hemolytic cleavage of the internal groups is the most plausible pathway for decomposition to pyrenes. The pathway is changed to heterolytic cleavage when the internal groups on the dihydropyrenes are Cl-, Br-, and SMe-. Comparison of the activation barriers for syn (30.18 kcal mol-1) and anti (32.10 kcal mol-1) dimethyldihydropyrenes for radical pathway reveal that decomposition of syn- DHP is more facile over anti-, which is consistent with the experimental observation. The decomposition pathway for syn-dihydropyrene is also hemolytic in cleavage when the internal groups are methyl and hydrogen. Syn-dihydropyrenes (symmetrical or unsymmetrical) bearing CN group do not follow sigmatropic shift, quite contrary to the anti-dihydropyrene. The lack of tendency of the syn-dihydropyrene for sigmatropic shift is rationalized on the planarity of the scaffold. The results of the theoretical study are consistent with the experimental observations. The results here help in understanding the behavior of substituents on the dihydropyrene scaffold, which will be useful in designing new molecules with improved thermal stabilities. Graphical abstract Functional group dependent decomposition pathways of dihydropyrenes.
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Affiliation(s)
- Bibi Saima
- Department of Chemistry, COMSATS University, Abbottabad Campus, Abbottabad, 22060, Pakistan
| | - Yan Alexander Wang
- Department of Chemistry, University of British Columbia, Vancouver, V6T 1Z1, Canada
| | - Riaz Hussain
- Department of Chemistry, University of Okara, Okara, Punjab, Pakistan
| | - Shabbir Muhammad
- Department of Physics, College of Science, King Khalid University, Abha, Saudi Arabia.,Research Center for Advanced Materials Science (RCAMS), King Khalid University, Abha, Saudi Arabia
| | - Khurshid Ayub
- Department of Chemistry, COMSATS University, Abbottabad Campus, Abbottabad, 22060, Pakistan.
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13
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Michel CS, Lampkin PP, Shezaf JZ, Moll JF, Castro C, Karney WL. Tunneling by 16 Carbons: Planar Bond Shifting in [16]Annulene. J Am Chem Soc 2019; 141:5286-5293. [PMID: 30845804 DOI: 10.1021/jacs.8b13131] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Midsized annulenes are known to undergo rapid π-bond shifting. Given that heavy-atom tunneling plays a role in planar bond shifting of cyclobutadiene, we computationally explored the contribution of heavy-atom tunneling to planar π-bond shifting in the major (CTCTCTCT, 5a) and minor (CTCTTCTT, 6a) known isomers of [16]annulene. UM06-2X/cc-pVDZ calculations yield bond-shifting barriers of ca. 10 kcal/mol. The results also reveal extremely narrow barrier widths, suggesting a high probability of tunneling for these bond-shifting reactions. Rate constants were calculated using canonical variational transition state theory (CVT) as well as with small curvature tunneling (SCT) contributions, via direct dynamics. For the major isomer 5a, the computed SCT rate constant for bond shifting at 80 K is 0.16 s-1, corresponding to a half-life of 4.3 s, and indicating that bond shifting is rapid at cryogenic temperatures despite a 10 kcal/mol barrier. This contrasts with the CVT rate constant of 8.0 × 10-15 s-1 at 80 K. The minor isomer 6a is predicted to undergo rapid bond shifting via tunneling even at 10 K. For both isomers, bond shifting is predicted to be much faster than competing conformation change despite lower barriers for the latter process. The preference for bond shifting represents cases of tunneling control in which the preferred reaction is dominated by heavy-atom motions. At all temperatures below -50 °C, tunneling is predicted to dominate the bond shifting process for both 5a and 6a. Thus, [16]annulene is predicted to be an example of tunneling by 16 carbons. Bond shifting in both isomers is predicted to be rapid at temperatures accessible by solution-phase NMR spectroscopy, and an experiment is proposed to verify these predictions.
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Affiliation(s)
- Cameron S Michel
- Department of Chemistry , University of San Francisco , 2130 Fulton Street , San Francisco , California 94117 , United States
| | - Philip P Lampkin
- Department of Chemistry , University of San Francisco , 2130 Fulton Street , San Francisco , California 94117 , United States
| | - Jonathan Z Shezaf
- Department of Chemistry , University of San Francisco , 2130 Fulton Street , San Francisco , California 94117 , United States
| | - Joseph F Moll
- Department of Chemistry , University of San Francisco , 2130 Fulton Street , San Francisco , California 94117 , United States
| | - Claire Castro
- Department of Chemistry , University of San Francisco , 2130 Fulton Street , San Francisco , California 94117 , United States
| | - William L Karney
- Department of Chemistry , University of San Francisco , 2130 Fulton Street , San Francisco , California 94117 , United States
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14
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Nikpassand M, Fekri LZ, Rahro PN. Catalyst-free grinding method: a new avenue for synthesis of 6-amino-3-methyl-4-aryl-1H-pyrazolo[3,4-b]pyridine-5-carbonitrile and DFT studies on the mechanistic pathway of this category of compounds. RESEARCH ON CHEMICAL INTERMEDIATES 2019. [DOI: 10.1007/s11164-018-3701-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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15
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Srinivasulu G, Vijayakumar S, Rajakumar B. Kinetic Investigations on the Gas Phase Reaction of 2,2,2-Trifluoroethylbutyrate with OH Radicals: An Experimental and Theoretical Study. ChemistrySelect 2018. [DOI: 10.1002/slct.201703113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Gonu Srinivasulu
- Department of Chemistry; Indian Institute of Technology Madras; Chennai 600036 India
| | - Siripina Vijayakumar
- Department of Chemistry; Indian Institute of Technology Madras; Chennai 600036 India
| | - Balla Rajakumar
- Department of Chemistry; Indian Institute of Technology Madras; Chennai 600036 India
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16
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Eckhardt AK, Gerbig D, Schreiner PR. Heavy Atom Secondary Kinetic Isotope Effect on H-Tunneling. J Phys Chem A 2018; 122:1488-1495. [DOI: 10.1021/acs.jpca.7b12118] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- André K. Eckhardt
- Institute of Organic Chemistry, Justus-Liebig University, Heinrich-Buff-Ring
17, 35392 Giessen, Germany
| | - Dennis Gerbig
- Institute of Organic Chemistry, Justus-Liebig University, Heinrich-Buff-Ring
17, 35392 Giessen, Germany
| | - Peter R. Schreiner
- Institute of Organic Chemistry, Justus-Liebig University, Heinrich-Buff-Ring
17, 35392 Giessen, Germany
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17
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Ilieva ED, Petrova GP, Nikolova RD, Vayssilov GN. Computational elucidation of the reaction mechanism for synthesis of pyrrolidinedione derivatives via Nef-type rearrangement – cyclization reaction. RSC Adv 2018; 8:3178-3188. [PMID: 35541181 PMCID: PMC9077586 DOI: 10.1039/c7ra11908a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2017] [Accepted: 01/08/2018] [Indexed: 02/03/2023] Open
Abstract
This paper reports a quantum chemical study of all stages of a one-pot synthesis of pyrrolidinedione derivatives from nitromethane and coumarin, which includes Michael addition, migration of an oxygen atom (Nef-type rearrangement), and cyclization to a pyrrolidine ring. The energy barrier of deprotonated nitromethane addition to coumarin is 21.7 kJ mol−1, while the barrier of proton transfer from the methylene to the nitro group in the nitromethyl group is notably higher, 197.8 kJ mol−1. The second stage of the reaction, migration of an oxygen atom within the nitromethyl group, occurs with lowest energy barrier, 142.4 kJ mol−1, when it is assisted by an additional water molecule. The last stage – cyclization, passes with a very low energy barrier of 11.9 kJ mol−1 but the tautomerization of the nitrosohydroxymethyl group to the hydroxy-N-hydroxyiminomethyl, necessary for the process, has an energy barrier of 178.4 kJ mol−1. Analogous calculations for the same process with the ethyl ester of 3-coumarin-carboxylic acid as substrate show that the relative energies of the intermediates and transition states are by at most 10–16 kJ mol−1 more stable than the corresponding structures with coumarin. A quantum chemical study of all stages of pyrrolidinedione derivative synthesis from nitromethane and coumarin, which includes Michael addition, migration of an oxygen atom (Nef-type rearrangement), and cyclization to a pyrrolidine ring is reported.![]()
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Affiliation(s)
| | - Galina P. Petrova
- Faculty of Chemistry and Pharmacy
- University of Sofia
- 1126 Sofia
- Bulgaria
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18
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Schreiner PR. Tunneling Control of Chemical Reactions: The Third Reactivity Paradigm. J Am Chem Soc 2017; 139:15276-15283. [DOI: 10.1021/jacs.7b06035] [Citation(s) in RCA: 116] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Peter R. Schreiner
- Institute of Organic Chemistry, Justus-Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
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Nandi A, Gerbig D, Schreiner PR, Borden WT, Kozuch S. Isotope-Controlled Selectivity by Quantum Tunneling: Hydrogen Migration versus Ring Expansion in Cyclopropylmethylcarbenes. J Am Chem Soc 2017. [PMID: 28635268 DOI: 10.1021/jacs.7b04593] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Using the tunneling-controlled reactivity of cyclopropylmethylcarbene, we demonstrate the viability of isotope-controlled selectivity (ICS), a novel control element of chemical reactivity where a molecular system with two conceivable products of tunneling exclusively produces one or the other, depending only on isotopic composition. Our multidimensional small-curvature tunneling (SCT) computations indicate that, under cryogenic conditions, 1-methoxycyclopropylmethylcarbene shows rapid H-migration to 1-methoxy-1-vinylcyclopropane, whereas deuterium-substituted 1-methoxycyclopropyl-d3-methylcarbene undergoes ring expansion to 1-d3-methylcyclobutene. This predicted change in reactivity constitutes the first example of a kinetic isotope effect that discriminates between the formation of two products.
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Affiliation(s)
- Ashim Nandi
- Department of Chemistry, Ben-Gurion University of the Negev , Beer-Sheva 841051, Israel
| | - Dennis Gerbig
- Justus-Liebig University , Heinrich-Buff-Ring 17, 35392 Giessen, Germany
| | - Peter R Schreiner
- Justus-Liebig University , Heinrich-Buff-Ring 17, 35392 Giessen, Germany
| | - Weston Thatcher Borden
- Center for Advanced Scientific Computing and Modeling (CASCAM), Department of Chemistry, University of North Texas , Denton, Texas 76203, United States
| | - Sebastian Kozuch
- Department of Chemistry, Ben-Gurion University of the Negev , Beer-Sheva 841051, Israel
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Vijayakumar S, Kumar A, Rajakumar B. Experimental and computational kinetic investigations for the reactions of Cl atoms with unsaturated ketones in the gas phase. NEW J CHEM 2017. [DOI: 10.1039/c7nj03209a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cl atom initiated photo oxidation of unsaturated ketones.
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Affiliation(s)
- S. Vijayakumar
- Department of Chemistry
- Indian Institute of Technology Madras
- Chennai 600036
- India
| | - Avinash Kumar
- Department of Chemistry
- Indian Institute of Technology Madras
- Chennai 600036
- India
| | - B. Rajakumar
- Department of Chemistry
- Indian Institute of Technology Madras
- Chennai 600036
- India
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21
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Vijayakumar S, Ramya CB, Kumar A, Rajakumar B. Kinetic investigations of Cl atom initiated photo-oxidation reactions of cyclic unsaturated hydrocarbons in the gas phase: an experimental and theoretical study. NEW J CHEM 2017. [DOI: 10.1039/c7nj01721a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cl atom initiated photo oxidation kinetics of cyclohexene and cycloheptene.
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Affiliation(s)
- S. Vijayakumar
- Department of Chemistry
- Indian Institute of Technology Madras
- Chennai 600036
- India
| | - C. B. Ramya
- Department of Chemistry
- Indian Institute of Technology Madras
- Chennai 600036
- India
| | - Avinash Kumar
- Department of Chemistry
- Indian Institute of Technology Madras
- Chennai 600036
- India
| | - B. Rajakumar
- Department of Chemistry
- Indian Institute of Technology Madras
- Chennai 600036
- India
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