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Silva AJFWHDS, Rodrigues GP, Ventura E, do Monte SA. Photodissociation and formation of an ion-pair in CH 2 FCl (HCFC-31). J Comput Chem 2024; 45:476-486. [PMID: 37950575 DOI: 10.1002/jcc.27257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Revised: 10/30/2023] [Accepted: 11/01/2023] [Indexed: 11/12/2023]
Abstract
Although CH2 FCl (HCFC-31) recently became of great atmospheric importance, studies concerning its excited states are almost nonexistent. Several excited singlet states were studied (valence nσ* and Rydberg n3s, n3p, σ3s, and σ3p) through highly correlated multireference configuration interaction with singles and doubles, including extensivity correction. Comparison with the states of CH3 Cl indicates a strong influence of the F atom. Potential energy curves suggest formation of an electrostatically bound complex that relaxes to a hydrogen-bonded contact ion-pair (HBCIP) which can decay yielding CH2 F + Cl or to the ground state minimum of CH2 FCl. The HBCIP has a dipole moment of 9.57 D, a CI wavefunction described as 0.65ionic + 0.20biradical and it is strongly bonded by 4.72 eV. Its H bond has characteristics of moderate and strong H bonds. The simulated absorption spectrum confirms the nσ* assignment for the first and suggests the n3s + n3pσ assignment for the second band.
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Affiliation(s)
| | | | - Elizete Ventura
- Chemistry Department, Universidade Federal da Paraíba, Joao Pessoa, Brazil
| | - Silmar A do Monte
- Chemistry Department, Universidade Federal da Paraíba, Joao Pessoa, Brazil
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2
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Hydrogen-bonded contact ion pair in gaseous chloroethane: a multi-reference configuration interaction with singles and doubles (MR-CISD) study including extensivity corrections. Theor Chem Acc 2020. [DOI: 10.1007/s00214-020-2561-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Pereira Rodrigues G, Lopes de Lima TM, de Andrade RB, Ventura E, do Monte SA, Barbatti M. Photoinduced Formation of H-Bonded Ion Pair in HCFC-133a. J Phys Chem A 2019; 123:1953-1961. [DOI: 10.1021/acs.jpca.8b12482] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gessenildo Pereira Rodrigues
- Universidade Federal da Paraíba, 58059-900, João Pessoa-PB, Brazil
- Faculdade Rebouças, 58406-040, Campina Grande-PB, Brazil
| | | | | | - Elizete Ventura
- Universidade Federal da Paraíba, 58059-900, João Pessoa-PB, Brazil
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de Medeiros VC, de Andrade RB, P. Rodrigues G, Bauerfeldt GF, Ventura E, Barbatti M, do Monte SA. Photochemistry of CF3Cl: Quenching of Charged Fragments Is Caused by Nonadiabatic Effects. J Chem Theory Comput 2018; 14:4844-4855. [DOI: 10.1021/acs.jctc.8b00457] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Vanessa C. de Medeiros
- Departamento de Química, CCEN, Universidade Federal da Paraíba, João Pessoa, Paraíba 58.059-900, Brazil
| | - Railton B. de Andrade
- Departamento de Química, CCEN, Universidade Federal da Paraíba, João Pessoa, Paraíba 58.059-900, Brazil
| | - Gessenildo P. Rodrigues
- Departamento de Química, CCEN, Universidade Federal da Paraíba, João Pessoa, Paraíba 58.059-900, Brazil
| | - Glauco F. Bauerfeldt
- Departamento de Química, Instituto de Ciências Exatas, UFRRJ, Pavilhão Roberto Alvahydo (PQ), sala 44. km 7, Rodovia Br 465, Seropédica, Rio de Janeiro 23890-000, Brazil
| | - Elizete Ventura
- Departamento de Química, CCEN, Universidade Federal da Paraíba, João Pessoa, Paraíba 58.059-900, Brazil
| | | | - Silmar A. do Monte
- Departamento de Química, CCEN, Universidade Federal da Paraíba, João Pessoa, Paraíba 58.059-900, Brazil
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Abstract
We have investigated the photodynamics of β-d-glucose employing our field-induced surface-hopping (FISH) method, which allows us to simulate the coupled electron-nuclear dynamics, explicitly including nonadiabatic effects and light-induced excitation. Our results reveal that from the initially populated S1 and S2 states, glucose returns nonradiatively to the ground state within about 200 fs. This takes place mainly via conical intersections (CIs), whose geometries in most cases involve the elongation of a single O-H bond, whereas in some instances, ring-opening due to dissociation of a C-O bond is observed. Experimentally, excitation to a distinct excited electronic state is improbable due to the presence of a dense manifold of states bearing similar oscillator strengths. Our FISH simulations, explicitly including a UV laser pulse of 6.43 eV photon energy, reveal that after initial excitation, the population is almost equally spread over several close-lying electronic states. This is followed by a fast nonradiative decay on the time scale of 100-200 fs, with the final return to the ground state proceeding via the S1 state through the same types of CIs as observed in the field-free simulations.
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Affiliation(s)
- Jens Petersen
- Institut für physikalische und theoretische Chemie, Julius-Maximilians-Universität Würzburg , Emil-Fischer-Str. 42, 97074 Würzburg, Germany
| | - Joachim O Lindner
- Institut für physikalische und theoretische Chemie, Julius-Maximilians-Universität Würzburg , Emil-Fischer-Str. 42, 97074 Würzburg, Germany
| | - Roland Mitrić
- Institut für physikalische und theoretische Chemie, Julius-Maximilians-Universität Würzburg , Emil-Fischer-Str. 42, 97074 Würzburg, Germany
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de Medeiros VC, de Andrade RB, Leitão EFV, Ventura E, Bauerfeldt GF, Barbatti M, do Monte SA. Photochemistry of CH3Cl: Dissociation and CH···Cl Hydrogen Bond Formation. J Am Chem Soc 2015; 138:272-80. [PMID: 26653216 DOI: 10.1021/jacs.5b10573] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
State-of-the-art electronic structure calculations (MR-CISD) are used to map five different dissociation channels of CH3Cl along the C-Cl coordinate: (i) CH3(X̃(2)A2″) + Cl((2)P), (ii) CH3(3s(2)A1') + Cl((2)P), (iii) CH3(+)((1)A1') + Cl(-)((1)S), (iv) CH3(3p(2)E') + Cl((2)P), and (v) CH3(3p(2)A2″) + Cl((2)P). By the first time these latter four dissociation channels, accessible upon VUV absorption, are described. The corresponding dissociation limits, obtained at the MR-CISD+Q level, are 3.70, 9.50, 10.08, 10.76, and 11.01 eV. The first channel can be accessed through nσ* and n3s states, while the second channel can be accessed through n(e)3s, n(e)3p(σ), and σ3s states. The third channel, corresponding to the CH3(+) + Cl(-) ion-pair, is accessed through n(e)3p(e) states. The fourth is accessed through n(e)3p(e), n(e)3p(σ), and σ3p(σ), while the fifth through σ3p(e) and σ(CH)σ* states. The population of the diverse channels is controlled by two geometrical spots, where intersections between multiple states allow a cascade of nonadiabatic events. The ion-pair dissociation occurs through formation of CH3(+)···Cl(-)and H2CH(+)···Cl(-) intermediate complexes bound by 3.69 and 4.65 eV. The enhanced stability of the H2CH(+)···Cl(-) complex is due to a CH···Cl hydrogen bond. A time-resolved spectroscopic setup is proposed to detect those complexes.
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Affiliation(s)
- Vanessa C de Medeiros
- Departamento de Química, CCEN, Universidade Federal da Paraíba , João Pessoa, PB 58059-900, Brazil
| | - Railton B de Andrade
- Departamento de Química, CCEN, Universidade Federal da Paraíba , João Pessoa, PB 58059-900, Brazil
| | - Ezequiel F V Leitão
- Departamento de Química, CCEN, Universidade Federal da Paraíba , João Pessoa, PB 58059-900, Brazil
| | - Elizete Ventura
- Departamento de Química, CCEN, Universidade Federal da Paraíba , João Pessoa, PB 58059-900, Brazil
| | - Glauco F Bauerfeldt
- Departamento de Química, Instituto de Ciências Exatas, UFRRJ, Pavilhão Roberto Alvahydo (PQ) , sala 44. km 7, Rodovia Br 465, Seropédica, RJ 23890-000, Brazil
| | - Mario Barbatti
- Aix Marseille Université , CNRS, ICR UMR7273, 13397 Marseille, France
| | - Silmar A do Monte
- Departamento de Química, CCEN, Universidade Federal da Paraíba , João Pessoa, PB 58059-900, Brazil
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de Andrade RB, Vieira Leitão EF, de Souza MAF, Ventura E, do Monte SA. Effect of methylation on relative energies of tautomers and on the intramolecular proton transfer barriers of protonated nitrosamine: A MR-CISD study. J Comput Chem 2015; 36:2027-36. [PMID: 26171999 DOI: 10.1002/jcc.24007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Accepted: 06/22/2015] [Indexed: 01/09/2023]
Abstract
MR-CISD, MR-CISD+Q, and MR-AQCC calculations have been performed on the minima and transition states (corresponding to intramolecular proton transfer between the protonation sites) of the ground state of protonated nitrosamine and N,N-dimethylnitrosamine. Our highest level results (MR-AQCC/cc-pVTZ) for the smaller system indicate that protonation on the N amino (2a) is practically as favorable as the most favorable protonation on the O atom (1a). They also suggest that protonation on the nitroso N atom (2c) is ∼14.5 kcal/mol less favorable than 1a. Results obtained at the MR-CISD+Q/cc-pVTZ level indicate that the effect of methylation on the relative energies of the tautomers is, in order of importance, 2a > 2c and increases their energies by ∼17.5 and 4.8 kcal/mol, respectively. They also indicate that methylation alters significantly the intramolecular proton transfer barriers. The largest differences between the common geometric parameters of both systems have been found for 2a.
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Affiliation(s)
| | | | | | - Elizete Ventura
- Departamento de Química, CCEN, Universidade Federal da Paraíba, João Pessoa, PB, 58.059-900, Brazil
| | - Silmar Andrade do Monte
- Departamento de Química, CCEN, Universidade Federal da Paraíba, João Pessoa, PB, 58.059-900, Brazil
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Pereira Rodrigues G, Ventura E, do Monte SA, Barbatti M. Photochemical Deactivation Process of HCFC-133a (C2H2F3Cl): A Nonadiabatic Dynamics Study. J Phys Chem A 2014; 118:12041-9. [DOI: 10.1021/jp507681g] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Gessenildo Pereira Rodrigues
- Universidade Federal da Paraiba, 58059-900, João Pessoa-Paraíba, Brazil
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Elizete Ventura
- Universidade Federal da Paraiba, 58059-900, João Pessoa-Paraíba, Brazil
| | | | - Mario Barbatti
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
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Accurate calculation of the ionization energies of the chlorine lone pairs in 1,1,1-trifluoro-2-chloroethane (HCFC-133a). J Mol Model 2014; 20:2393. [PMID: 25135066 DOI: 10.1007/s00894-014-2393-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2014] [Accepted: 07/22/2014] [Indexed: 10/24/2022]
Abstract
The vertical ionization energies of the chlorine lone pairs in HCFC-133a have been calculated at the SCF (via Koopmans' theorem and including orbital relaxation) and correlated (ROMP2, OVGF, and ROCCSD(T)) levels. Dunning aug-cc-pVXZ (X = D, T, and Q) basis sets were employed, and the ROMP2 and ROCCSD(T) results were extrapolated to the complete basis set (CBS) limit. Our highest-level results (obtained at the ROCCSD(T)/CBS level) were 11.99 and 12.08 eV for the Cl lone pairs of A″ and A' symmetry, respectively. The values obtained at the computationally much less demanding ROMP2/CBS level were just 0.10 and 0.13 eV higher than the highest-level ones. Using the Cl lone-pair band of the photoelectron spectrum of the HCF(2)Cl and CF(3)Cl molecules as a guide, it is considered very unlikely that these two lone pairs can be discriminated in the photoelectron spectrum of the title molecule. The use of the calculated IPs to estimate the energies of the Rydberg states of HCFC-133a is also discussed.
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de Medeiros VC, do Monte SA, Ventura E. Valence and Rydberg states of CH3Cl: a MR-CISD study. RSC Adv 2014. [DOI: 10.1039/c4ra10567b] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In this work ten singlet and nine triplet states are studied through multi-reference configuration interactions with singles and doubles (MR-CISD), including Davidson extensivity correction (MR-CISD+Q).
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Affiliation(s)
| | - Silmar A. do Monte
- Departamento de Química
- CCEN
- Universidade Federal da Paraíba
- João Pessoa, Brazil
| | - Elizete Ventura
- Departamento de Química
- CCEN
- Universidade Federal da Paraíba
- João Pessoa, Brazil
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Rodrigues GP, Lucena JR, Ventura E, do Monte SA, Reva I, Fausto R. Matrix isolation infrared spectroscopic and theoretical study of 1,1,1-trifluoro-2-chloroethane (HCFC-133a). J Chem Phys 2013; 139:204302. [PMID: 24289349 DOI: 10.1063/1.4832376] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The molecular structure and infrared spectrum of the atmospheric pollutant 1,1,1-trifluoro-2-chloroethane (HCFC-133a; CF3CH2Cl) in the ground electronic state were characterized experimentally and theoretically. Excited state calculations (at the CASSCF, MR-CISD, and MR-CISD+Q levels) have also been performed in the range up to ~9.8 eV. The theoretical calculations show the existence of one (staggered) conformer, which has been identified spectroscopically for the monomeric compound isolated in cryogenic (~10 K) argon and xenon matrices. The observed infrared spectra of the matrix-isolated HCFC-133a were interpreted with the aid of MP2/aug-cc-pVTZ calculations and normal coordinate analysis, which allowed a detailed assignment of the observed spectra to be carried out, including identification of bands due to different isotopologues ((35)Cl and (37)Cl containing molecules). The calculated energies of the several excited states along with the values of oscillator strengths and previous results obtained for CFCs and HCFCs suggest that the previously reported photolyses of the title compound at 147 and 123.6 nm [T. Ichimura, A. W. Kirk, and E. Tschuikow-Roux, J. Phys. Chem. 81, 1153 (1977)] are likely to be initiated in the n-4s and n-4p Rydberg states, respectively.
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