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Wagner JP. Designing a σ 0π 2 singlet ground state carbene from dicationic carbones. Chem Commun (Camb) 2024; 60:3327-3330. [PMID: 38436398 DOI: 10.1039/d4cc00492b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2024]
Abstract
Carbenes with a σ0π2 singlet ground state are rare and little is known about their chemistry. Here, we study the potential formation of such carbenes by removal of two electrons from carbones/donor-substituted allenes. The desired electron configuration becomes favorable in the case of bis-diiminium substitution (CAAC motif).
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Affiliation(s)
- J Philipp Wagner
- Institut für Organische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, 72076, Tübingen, Germany.
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2
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Hu C, Wang XF, Li J, Chang XY, Liu LL. A stable rhodium-coordinated carbene with a σ 0π 2 electronic configuration. Science 2024; 383:81-85. [PMID: 38175894 DOI: 10.1126/science.adk6533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Accepted: 11/20/2023] [Indexed: 01/06/2024]
Abstract
Isolable singlet carbenes have universally adopted a σ2π0 electronic state, making them σ-donors and π-acceptors. We present a rhodium-coordinated, cationic cyclic diphosphinocarbene with a σ0π2 ground state configuration. Nuclear magnetic resonance spectroscopy studies show a carbene carbon chemical shift below -30.0 parts per million. X-ray crystallography reveals a planar RhP2C configuration. Quantum chemical calculations rationalize how σ-electron delocalization/donation and π-electron negative hyperconjugation together stabilize the formally vacant σ orbital and the filled π orbital at the carbene center. In contrast to traditional carbene counterparts this carbene can undergo synthetic transformations with both a Lewis base and a silver salt, producing a Lewis acid/base adduct and a silver π-complex, respectively. Exhibiting ambiphilic reactivity, it can also form a ketenimine through reaction with an isocyanide.
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Affiliation(s)
- Chaopeng Hu
- Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Xin-Feng Wang
- Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Jiancheng Li
- Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Xiao-Yong Chang
- Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Liu Leo Liu
- Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, P. R. China
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3
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Mills JD. Applications of the Spectral Theory of Chemical Bonding to Simple Hydrocarbons. J Phys Chem A 2023; 127:1998-2010. [PMID: 36802578 DOI: 10.1021/acs.jpca.2c07432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
The finite-basis, pair formulation of the Spectral Theory of chemical bonding is briefly surveyed. Solutions of the Born-Oppenheimer polyatomic Hamiltonian that are totally antisymmetric in electron exchange are obtained from diagonalization of an aggregate matrix built up from conventional diatomic solutions to atom-localized problems. A succession of transformations of the bases of the underlying matrices and the unique character of symmetric orthogonalization in producing the archived matrices calculated "once-of-all" in the pairwise-antisymmetrized basis are described. Application is made to molecules containing hydrogens and a single carbon atom. Results in conventional orbital bases are given and compared to experimental and high-level theoretical results. Chemical valence is shown to be respected and subtle angular effects in polyatomic contexts are reproduced. Means of reducing the size of the atomic-state basis and improving the fidelity of the diatomic descriptions for fixed basis size, so as to enable application to larger polyatomic molecules, are outlined along with future initiatives and prospects.
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Affiliation(s)
- Jeffrey D Mills
- Air Force Research Laboratory, 10 East Saturn Boulevard, Edwards AFB, California 93524, United States
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4
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Zhao J, Zhang L, Yue D, Liu D, Gao S, Wang L, Meng Q. Effect of the reactant vibration on quantum dynamics of the reaction H + CH(v = 0,1,2, j = 0) → H2 + C based on a new CH2(X3A″) potential energy surface. Chem Phys 2022. [DOI: 10.1016/j.chemphys.2022.111677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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5
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Kalemos A. CH 4, an ab initio story of an archetypal species. J Chem Phys 2022; 156:214303. [DOI: 10.1063/5.0088788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The methane molecule is an archetypal species in the whole of chemistry for its ability to form four bonds that result in a myriad of compounds of chemical and biological importance. The hybrid orbitals involved in the bonding have been scrutinized for too many decades but only lately under the ab initio microscope. In this study, we detail the formation routes CH n + (4 − n) H → CH4 ( n = 0, 1, and 2) both diabatically and adiabatically with the help of established computational techniques. The evolution of the Mulliken populations, of the non-adiabatic matrix coupling elements, and of the Kotani spin functions along the dissociation paths and finally the shape of the diabatic curves unambiguously point to a parental C atom of an excited 2 s12 p3 electronic configuration.
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Affiliation(s)
- Apostolos Kalemos
- Department of Chemistry, Laboratory of Physical Chemistry, National and Kapodistrian University of Athens, Athens 157 71, Greece
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6
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Kalemos A. An ab initio study on the bonding in H 2CO 3 and related species. Mol Phys 2021. [DOI: 10.1080/00268976.2021.1952327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Apostolos Kalemos
- Department of Chemistry, Laboratory of Physical Chemistry, National and Kapodistrian University of Athens, Athens, Greece
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8
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9
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Ghafarian Shirazi R, Neese F, Pantazis DA. Accurate Spin-State Energetics for Aryl Carbenes. J Chem Theory Comput 2018; 14:4733-4746. [DOI: 10.1021/acs.jctc.8b00587] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Reza Ghafarian Shirazi
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Frank Neese
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Dimitrios A. Pantazis
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
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10
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Theoretical study on interactions of N-heterocyclic carbene with the bare first-row transition metals. Theor Chem Acc 2016. [DOI: 10.1007/s00214-016-1922-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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11
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Miliordos E, Xantheas SS. The Origin of the Reactivity of the Criegee Intermediate: Implications for Atmospheric Particle Growth. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201509685] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Evangelos Miliordos
- Physical Sciences Division Pacific Northwest National Laboratory 902 Battelle Boulevard, P.O. Box 999, MS K1-83 Richland WA 99352 USA
| | - Sotiris S. Xantheas
- Physical Sciences Division Pacific Northwest National Laboratory 902 Battelle Boulevard, P.O. Box 999, MS K1-83 Richland WA 99352 USA
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12
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Miliordos E, Xantheas SS. The Origin of the Reactivity of the Criegee Intermediate: Implications for Atmospheric Particle Growth. Angew Chem Int Ed Engl 2015; 55:1015-9. [DOI: 10.1002/anie.201509685] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Indexed: 11/05/2022]
Affiliation(s)
- Evangelos Miliordos
- Physical Sciences Division Pacific Northwest National Laboratory 902 Battelle Boulevard, P.O. Box 999, MS K1-83 Richland WA 99352 USA
| | - Sotiris S. Xantheas
- Physical Sciences Division Pacific Northwest National Laboratory 902 Battelle Boulevard, P.O. Box 999, MS K1-83 Richland WA 99352 USA
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13
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Zhang C, Fu M, Shen Z, Ma H, Bian W. Global analytical ab initio ground-state potential energy surface for the C((1)D)+H2 reactive system. J Chem Phys 2014; 140:234301. [PMID: 24952535 DOI: 10.1063/1.4881896] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
A new global ab initio potential energy surface (called ZMB-a) for the 1(1)A' state of the C((1)D)+H2 reactive system has been constructed. This is based upon ab initio calculations using the internally contracted multireference configuration interaction approach with the aug-cc-pVQZ basis set, performed at about 6300 symmetry unique geometries. Accurate analytical fits are generated using many-body expansions with the permutationally invariant polynomials, except that the fit of the deep well region is taken from our previous fit. The ZMB-a surface is unique in the accurate description of the regions around conical intersections (CIs) and of van der Waals (vdW) interactions. The CIs between the 1(1)A' and 2(1)A' states cause two kinds of barriers on the ZMB-a surface: one is in the linear H-CH dissociation direction with a barrier height of 9.07 kcal/mol, which is much higher than those on the surfaces reported before; the other is in the C((1)D) collinearly attacking H2 direction with a barrier height of 12.39 kcal/mol. The ZMB-a surface basically reproduces our ab initio calculations in the vdW interaction regions, and supports a linear C-HH vdW complex in the entrance channel, and two vdW complexes in the exit channel, at linear CH-H and HC-H geometries, respectively.
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Affiliation(s)
- Chunfang Zhang
- Beijing National Laboratory for Molecular Sciences and Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Mingkai Fu
- Beijing National Laboratory for Molecular Sciences and Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Zhitao Shen
- Beijing National Laboratory for Molecular Sciences and Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Haitao Ma
- Beijing National Laboratory for Molecular Sciences and Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Wensheng Bian
- Beijing National Laboratory for Molecular Sciences and Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
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14
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15
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Accurate structural parameters and binding energy of the X1̃A1 state of diazomethane through coupled-cluster calculations. Chem Phys Lett 2014. [DOI: 10.1016/j.cplett.2014.03.058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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16
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Chen B, Rogachev AY, Hrovat DA, Hoffmann R, Borden WT. How to Make the σ0π2 Singlet the Ground State of Carbenes. J Am Chem Soc 2013; 135:13954-64. [DOI: 10.1021/ja407116e] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Bo Chen
- Department of
Chemistry and the Center for Advanced, Scientific Computing and Modeling, University of North Texas, 1155 Union Circle, #305070, DentonTexas, 76203-5070, United States
| | - Andrey Yu. Rogachev
- Department of
Chemistry and Chemical Biology, Cornell University, Baker Laboratory, Ithaca, New York 14853-1301, United States
| | - David A. Hrovat
- Department of
Chemistry and the Center for Advanced, Scientific Computing and Modeling, University of North Texas, 1155 Union Circle, #305070, DentonTexas, 76203-5070, United States
| | - Roald Hoffmann
- Department of
Chemistry and Chemical Biology, Cornell University, Baker Laboratory, Ithaca, New York 14853-1301, United States
| | - Weston Thatcher Borden
- Department of
Chemistry and the Center for Advanced, Scientific Computing and Modeling, University of North Texas, 1155 Union Circle, #305070, DentonTexas, 76203-5070, United States
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17
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Li BT, Wei ZZ, Wu HS. The valence and Rydberg excited states of CH2: A theoretical exploration. J Comput Chem 2012; 33:2498-503. [DOI: 10.1002/jcc.23075] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 07/04/2012] [Accepted: 07/09/2012] [Indexed: 11/10/2022]
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18
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New ab Initio Potential Energy Surfaces for the Renner-Teller Coupled 11A′
and 11A′′
States of CH2. ADVANCES IN CHEMICAL PHYSICS 2012. [DOI: 10.1155/2012/236750] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
New ab initio potential energy surfaces (PESs) for the two lowest-lying singlet 11A′ and 11A′′ electronic states of CH2, coupled by the Renner-Teller (RT) effect and meant for the spectroscopic study, are presented. The surfaces are constructed using a dual-level strategy. The internally contracted multireference
configuration interaction calculations with the Davidson correction, using the aug-cc-pVQZ basis set, are
employed to obtain 3042 points at the lower level. The core and core-valence correlation effects are taken
into account in the ab initio calculations with a modified optimized aug-cc-pCVQZ basis set for the higher-level points. The analytical representations of these PESs, with the inclusion of the nonadiabatic RT terms,
are obtained by the nonlinear least-squares fit of the calculated points to three-body expansion. Quantum
dynamical calculations are performed on these PESs, and the computed vibronic energy levels for the two
singlet electronic states are in excellent agreement with experiment.
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19
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Luzanov AV, Prezhdo OV. The spin-polarized extended Brueckner orbitals. J Chem Phys 2011; 135:094107. [DOI: 10.1063/1.3629780] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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20
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Kalemos A, Mavridis A. Myths and Reality of Hypervalent Molecules. The Electronic Structure of FClOx, x = 1−3, Cl3PO, Cl3PCH2, Cl3CClO, and C(ClO)4. J Phys Chem A 2011; 115:2378-84. [PMID: 21351781 DOI: 10.1021/jp111330y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Apostolos Kalemos
- Laboratory of Physical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, P.O. Box 64 004, 157 10 Zografou, Athens, Greece
| | - Aristides Mavridis
- Laboratory of Physical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, P.O. Box 64 004, 157 10 Zografou, Athens, Greece
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21
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Chang CH, Hall GE, Sears TJ. Sub-Doppler spectroscopy of mixed state levels in CH(2). J Chem Phys 2010; 133:144310. [PMID: 20950003 DOI: 10.1063/1.3502084] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Perturbations in the 7(16) and 8(18) mixed singlet/triplet levels of ã (1)A(1)(0,0,0) methylene, CH(2), have been reinvestigated by frequency-modulated laser sub-Doppler saturation spectroscopy. The hyperfine structure was completely resolved for both the predominantly singlet and the predominantly triplet components of these mixed rotational levels using b̃ (1)B(1)-ã (1)A(1) optical transitions near 12 200 cm(-1) with megahertz resolution. The mixing coefficients were obtained from the observed hyperfine splittings and a two-level deperturbation model. The analysis also determines the energy separation of the unperturbed zero-order levels and the unperturbed hyperfine splittings for the triplet perturbing levels 6(15) X̃ (3)B(1)(0,3,0) and 9(37) X̃ (3)B(1)(0,2,0).
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Affiliation(s)
- Chih-Hsuan Chang
- Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973, USA
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22
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Anderson AG, Goddard WA. Generalized valence bond wave functions in quantum Monte Carlo. J Chem Phys 2010; 132:164110. [DOI: 10.1063/1.3377091] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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23
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Tao C, Ebben C, Reid SA. Fluorescence excitation and emission spectroscopy of the X(1)A' --> A(1)A'' system of CHI and CDI. J Phys Chem A 2010; 113:13407-12. [PMID: 19438219 DOI: 10.1021/jp903047d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report on the first detailed studies of the spectroscopy of an iodocarbene, measuring fluorescence excitation and emission spectra of the X1A' --> A1A'' system of :CHI and the deuterated isotopomer :CDI. Due to similar bending and C-I stretching frequencies in the upper state, fluorescence excitation spectra of :CHI show polyads composed of members of the 2(0)(n-x)3(0)x progressions with x = 0-3. For :CDI, only progressions with x = 0, 1 are observed. Extrapolation of the 20n term energies for both isotopomers to a common origin places the electronic origin of the X1A' --> A1A'' system near 10500 cm-1, in good agreement with theoretical predictions. Rotational analysis of the 16 observed bands for CHI and 13 observed bands for :CDI yields rotational constants for the upper and lower states that are also in good agreement with theory. To investigate the controversial issue of the ground state multiplicity of :CHI, we measured single vibronic level emission spectra from many A1A'' levels. These spectra show conclusively that the ground state is a singlet, as for both isotopomers the ã3A'' origin is observed, lying well above the origin of the X1A' state. At energies above the ã3A'' origin, the spin-orbit mixing is so severe that few vibrational assignments can be made. Analysis of the emission spectra provides a lower limit on the singlet-triplet gap of 4.1 kcal mol-1, in excellent agreement with theoretical predictions.
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Affiliation(s)
- Chong Tao
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201-1881, USA
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24
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Ben-Nun M, Mills JD, Hinde RJ, Winstead CL, Boatz JA, Gallup GA, Langhoff PW. Atomic spectral-product representations of molecular electronic structure: metric matrices and atomic-product composition of molecular eigenfunctions. J Phys Chem A 2009; 113:7687-97. [PMID: 19552480 DOI: 10.1021/jp901427x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Recent progress is reported in development of ab initio computational methods for the electronic structures of molecules employing the many-electron eigenstates of constituent atoms in spectral-product forms. The approach provides a universal atomic-product description of the electronic structure of matter as an alternative to more commonly employed valence-bond- or molecular-orbital-based representations. The Hamiltonian matrix in this representation is seen to comprise a sum over atomic energies and a pairwise sum over Coulombic interaction terms that depend only on the separations of the individual atomic pairs. Overall electron antisymmetry can be enforced by unitary transformation when appropriate, rather than as a possibly encumbering or unnecessary global constraint. The matrix representative of the antisymmetrizer in the spectral-product basis, which is equivalent to the metric matrix of the corresponding explicitly antisymmetric basis, provides the required transformation to antisymmetric or linearly independent states after Hamiltonian evaluation. Particular attention is focused in the present report on properties of the metric matrix and on the atomic-product compositions of molecular eigenstates as described in the spectral-product representations. Illustrative calculations are reported for simple but prototypically important diatomic (H(2), CH) and triatomic (H(3), CH(2)) molecules employing algorithms and computer codes devised recently for this purpose. This particular implementation of the approach combines Slater-orbital-based one- and two-electron integral evaluations, valence-bond constructions of standard tableau functions and matrices, and transformations to atomic eigenstate-product representations. The calculated metric matrices and corresponding potential energy surfaces obtained in this way elucidate a number of aspects of the spectral-product development, including the nature of closure in the representation, the general redundancy or linear dependence of its explicitly antisymmetrized form, the convergence of the apparently disparate atomic-product and explicitly antisymmetrized atomic-product forms to a common invariant subspace, and the nature of a chemical bonding descriptor provided by the atomic-product compositions of molecular eigenstates. Concluding remarks indicate additional studies in progress and the prognosis for performing atomic spectral-product calculations more generally and efficiently.
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Affiliation(s)
- M Ben-Nun
- San Diego Supercomputer Center and Department of Chemistry & Biochemistry, University of California, 9500 Gilman Drive, La Jolla, California 92093-0505, USA
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25
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Kable SH, Reid SA, Sears TJ. The halocarbenes: model systems for understanding the spectroscopy, dynamics and chemistry of carbenes. INT REV PHYS CHEM 2009. [DOI: 10.1080/01442350903087792] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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26
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Joseph S, Varandas AJC. Accurate Double Many-Body Expansion Potential Energy Surface for the Lowest Singlet State of Methylene. J Phys Chem A 2009; 113:4175-83. [DOI: 10.1021/jp810600r] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- S. Joseph
- Departamento de Química, Universidade de Coimbra, 3004-535 Coimbra, Portugal
| | - A. J. C. Varandas
- Departamento de Química, Universidade de Coimbra, 3004-535 Coimbra, Portugal
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27
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28
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Li X, Paldus J. Electronic structure of organic diradicals: Evaluation of the performance of coupled-cluster methods. J Chem Phys 2008; 129:174101. [DOI: 10.1063/1.2999560] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
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29
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Wang Z, Kim Y, Hall GE, Sears TJ. State Mixing and Predissociation in the c̃ ← ã Band System of Singlet Methylene Studied by Optical−Optical Double Resonance. J Phys Chem A 2008; 112:9248-54. [DOI: 10.1021/jp801038e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Zhong Wang
- Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973-5000
| | - Yangsoo Kim
- Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973-5000
| | - Gregory E. Hall
- Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973-5000
| | - Trevor J. Sears
- Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973-5000
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30
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Calhorda MJ, Krapp A, Frenking G. A New Look at the Ylidic Bond in Phosphorus Ylides and Related Compounds: Energy Decomposition Analysis Combined with a Domain-Averaged Fermi Hole Analysis. J Phys Chem A 2007; 111:2859-69. [PMID: 17388399 DOI: 10.1021/jp057320v] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Geometries and bond dissociation energies of the ylide compounds H2CPH3, H2CPMe3, H2CPF3, (BH2)2CPH3, H2CNH3, H2CAsH3, H2SiPH3, and (BH2)2SiPH3 have been calculated using ab initio (MP2, CBS-QB3) and DFT (B3LYP, BP86) methods. The nature of the ylidic bond R2E1-E2X3 was investigated with an energy decomposition analysis and with the domain-averaged Fermi hole (DAFH) analysis. The results of the latter method indicate that the peculiar features of the ylidic bond can be understood in terms of donor-acceptor interactions between closed-shell R2E1 and E2X3 fragments. The DAFH analysis clearly shows that there are two bonding contributions to the ylidic bond. The strength of the donor and acceptor contributions to the attractive orbital interactions can be estimated from the energy decomposition analysis (EDA) calculations, which give also the contributions of the electrostatic attraction and the Pauli repulsion of the chemical bonding. The EDA and DAFH results clearly show that the orbital interactions take place through the singlet ground state of the R2E1 fragment where the donor orbital of E1 yields pi-type back-donation while the E2X3 lone-pair orbital yields sigma-type bonding. Both bonds are polarized toward E2X3 when E2 = P, while the sigma-type bonding remains more polarized at E2X3 when E2 = N, As. This shows that the phosphorus ylides exhibit a particular bonding situation which is clearly different from that of the nitrogen and arsenic homologues. With ylides built around a P-C linkage, the pi-acceptor strength of phosphorus and the sigma-acceptor strength at carbon contribute to a double bond which is enhanced by electrostatic contributions. The strength of the sigma and pi components and the electrostatic attraction are then fine-tuned by the substituents at C and P, which yields a peculiar type of carbon-phosphorus bonding. The EDA data reveal that the relative strength of the ylidic bond may be determined not only by the R2E1 --> E2X3 pi back-donation, but also by the electrostatic contribution to the bonding. The calculations of the R2E1-E2X3 bond dissociation energy using ab initio methods predict that the order of the bond strength is H2C-PMe3 > H2C-PF3 > H2C-PH3 > (BH2)2C-PH3 > H2C-AsH3 > H2C-NH3 approximately H2Si-PH3 approximately (BH2)2Si-PH3. The DFT methods predict a similar trend, but they underestimate the bond strength of (BH2)2CPH3.
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Affiliation(s)
- Maria José Calhorda
- Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal
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Tao C, Mukarakate C, Reid SA. Fluorescence excitation and single vibronic level emission spectroscopy of the ÃA″1←X̃A′1 system of CHCl. J Chem Phys 2006; 124:224314. [PMID: 16784281 DOI: 10.1063/1.2204916] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
We report new fluorescence excitation and single vibronic level emission spectra of the A (1)A(")<-->X (1)A(') system of CHCl. A total of 21 cold bands involving the pure bending levels 2(0) (n) with n=1-7 and combination bands 2(0) (n)3(0) (1)(n=4-7), 2(0) (n)3(0) (2)(n=4-6), 1(0) (1)2(0) (n)(n=5-7), 1(0) (1)2(0) (n)3(0) (1)(n=4-6), and 1(0) (1)2(0) (n)3(0) (2)(n=4) were observed in the 450-750 nm region; around half of these are reported and/or rotationally analyzed here for the first time. Spectra were measured under jet-cooled conditions using a pulsed discharge source, and rotational analysis typically yielded band origins and rotational constants for both isotopomers (CH(35)Cl,CH(37)Cl). The derived A (1)A(") vibrational intervals are combined with results of Chang and Sears to determine the excited state barrier to linearity [V(b)=1920(50) cm(-1)]. The A (1)A(") state C-H stretching frequency is determined here for the first time, in excellent agreement with ab initio predictions. Following our observation of new bands in this system, we obtained the single vibronic level (SVL) emission spectra which probe the vibrational structure of the X (1)A(') state up to approximately 9000 cm(-1) above the vibrationless level. The total number of X (1)A(') levels observed is around three times than that previously reported, and we observe five new a (3)A(") state levels, including all three fundamentals. The results of a Dunham expansion fit of the ground state vibrational term energies, and comparisons with the previous experimental and recent high level ab initio studies, are reported. Our data confirm the previous assignment of the a (3)A(") origin, and our value for T(00)(a-X)=2172(2) cm(-1) is in excellent agreement with theory. By exploiting SVL spectra from excited state levels with K(a) (')=1, we determine the effective rotational constant (A-B) of the triplet origin, also in good agreement with theory. Our results shed new light on the vibrational structure of the X (1)A('), A (1)A("), and a (3)A(") states of CHCl, and, more generally, spin-orbit coupling in the monohalocarbenes.
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Affiliation(s)
- Chong Tao
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201-1881, USA
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Joo H, Shevlin PB, McKee ML. Computational Study of Carbon Atom (3P and 1D) Reaction with CH2O. Theoretical Evaluation of 1B1 Methylene Production by C (1D). J Am Chem Soc 2006; 128:6220-30. [PMID: 16669692 DOI: 10.1021/ja060216m] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Singlet and triplet free energy surfaces for the reactions of C atom ((3)P and (1)D) with CH(2)O are studied computationally to evaluate the excited singlet ((1)B(1)) methylene formation from deoxygenation of CH(2)O by C ((1)D) atom as suggested by Shevlin et al. Carbon atoms can react by addition to the oxygen lone pair or to the C=O double bond on both the triplet and singlet surfaces. Triplet C ((3)P) atoms will deoxygenate to give CO plus CH(2) ((3)B(1)) as the major products, while singlet C ((1)D) reactions will form ketene and CO plus CH(2) ((1)A(1)). No definitive evidence of the formation of excited singlet ((1)B(1)) methylene was found on the singlet free energy surface. A conical intersection between the (1)A' and (1)A' ' surfaces located near an exit channel may play a role in product formation. The suggested (1)B(1) state of methylene may form via the (1)A' ' surface only if dynamic effects are important. In an effort to interpret experimental observation of products trapped by (Z)-2-butene, formation of cis- and trans-1,2-dimethylcyclopropane is studied computationally. The results suggests that "hot" ketene may react with (Z)-2-butene nonstereospecifically.
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Affiliation(s)
- Hyun Joo
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, USA
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Deselnicu M, Tao C, Mukarakate C, Reid SA. Fluorescence excitation and emission spectroscopy of the ÃA″1←X̃A′1 system of CHBr. J Chem Phys 2006; 124:134302. [PMID: 16613450 DOI: 10.1063/1.2183302] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report fluorescence excitation and emission spectra of CHBr in the 450-750 nm region. A total of 30 cold bands involving the pure bending levels 2(0)(n) with n=2-8 and combination bands 2(0)(n)3(0)(1)(n=1-8), 2(0) (n)3(0)(2)(n=1-6), 2(0)(n)3(0)(3)(n=1-2), 1(0)(1)2(0)(n)(n=5-7), 1(0)(1)2(0)(n)3(0)(1)(n=4-6), and 1(0)(1)2(0)(n)3(0)(2)(n=5) in the A (1)A(")<--X (1)A(') system were observed, in addition to a number of hot bands. The majority of these are reported and/or rotationally analyzed here for the first time. Spectra were measured under jet-cooled conditions using a pulsed discharge source, and rotational analysis yielded band origins and rotational constants for both bromine isotopomers (CH (79)Br,CH (81)Br). The derived A (1)A(") vibrational intervals are combined with results of [Yu et al. J. Chem. Phys. 115, 5433 (2001)] to derive barriers to linearity for the 2(n), 2(n)3(1), and 2(n)3(2) progressions. The A (1)A(") state C-H stretching frequency is determined here for the first time, and the observed nu(3) dependence of the (79)Br-(81)Br isotope splitting in the A(1)A(") state is in good agreement with theoretical expectations. Our dispersed fluorescence spectra probe the vibrational structure of the X(1)A(') state up to approximately 9000 cm(-1) above the vibrationless level; the total number of levels observed is more than twice that previously reported. As first reported by [Chen et al. J. Mol. Spectrosc. 209, 254 (2001)], these spectra reveal numerous perturbations due to spin-orbit interaction with the low-lying a(3)A(") state. The results of a Dunham expansion fit of the ground state vibrational term energies, and comparisons with previous experimental and theoretical studies, are reported. Our results lead to several revised assignments, including the X (1)A(') C-H stretching fundamental. Globally, the vibrational frequencies of X(1)A('), a(3)A("), and A(1)A(") are in excellent agreement with theoretical predictions.
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Affiliation(s)
- Mihaela Deselnicu
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201-1881, USA
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Kerkines ISK, Carsky P, Mavridis A. A Multireference Coupled-Cluster Potential Energy Surface of Diazomethane, CH2N2. J Phys Chem A 2005; 109:10148-52. [PMID: 16838935 DOI: 10.1021/jp054530z] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The intrinsically multireference dissociation of the C-N bond in ground-state diazomethane (CH(2)N(2)) at different angles has been studied with the multireference Brillouin-Wigner coupled-cluster singles and doubles (MRBWCCSD) method. The morphology of the calculated potential energy surface (PES) in C(s)() symmetry is similar to a multireference perturbational (CASPT3) PES. The MRBWCCSD/cc-pVTZ H(2)C-N(2) dissociation energy with respect to the asymptotic CH(2)(ã(1)A(1)) + N(2)(X(1)Sigma(g)(+)) products is D(e) = 35.9 kcal/mol, or a zero-point corrected D(0) = 21.4 kcal/mol with respect to the ground-state CH(2)(X(3)B(1)) + N(2)(X(1)Sigma(g)(+)) fragments.
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Affiliation(s)
- Ioannis S K Kerkines
- Laboratory of Physical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, PO Box 64004, 15710 Zografou, Athens, Greece
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Flores JR, Gdanitz RJ. Accurately solving the electronic Schrödinger equation of small atoms and molecules using explicitly correlated (r12-)MR-CI. VIII. Valence excited states of methylene (CH2). J Chem Phys 2005; 123:144316. [PMID: 16238400 DOI: 10.1063/1.2055207] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
We compute the adiabatic transition energies of methylene (CH(2)) from the ground state to the lowest electronically excited valence states using the r(12)-MR-ACPF-2 method with a large basis set and an extended reference space. We recall that this method aims at reaching the basis-set and full configuration interaction (CI) limits simultaneously. Our best excitation energies, T(e) (T(0)), are 9.22 (8.87) (a (1)A(1), corrected for relativistic and adiabatic effects), 31.98 (31.86) (b (1)B(1)), and 57.62 (57.18) kcal mol(-1) (c (1)A(1)) (both uncorrected). We are able to reach the respective basis-set limits that closely that the remaining errors of our (uncorrected) calculations are clearly due to the MR-ACPF-2 method. While we are unable to assess the error of the latter method in a systematic way, we still believe that it is rather unlikely that the errors of our excitation energies exceed +/-0.10 kcal mol(-1). We finally observe that our (corrected) a state values deviate by only -0.10 (-0.10) kcal mol(-1) from the results of Csaszar et al. [J. Chem. Phys. 118, 10631 (2003)]--who did careful extrapolations to the valence full-CI and basis-set limits and added a correction for the core correlation--and that the deviation from experiment is only -0.13 (-0.13) kcal mol(-1). From these excellent agreements we conclude that our excitation energies to the b and c states are similarly accurate.
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Affiliation(s)
- Jesús R Flores
- Departamento de Química Física, Facultad de Química, Universidad de Vigo, E-36200 Vigo, Spain.
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