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Babin MC, DeWitt M, Weichman ML, DeVine JA, Neumark DM. High-resolution anion photoelectron spectroscopy of cryogenically cooled 4-atom silicon carbides. Mol Phys 2020. [DOI: 10.1080/00268976.2020.1817596] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Mark C. Babin
- Department of Chemistry, University of California, Berkeley, CA, USA
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Martin DeWitt
- Department of Chemistry, University of California, Berkeley, CA, USA
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Marissa L. Weichman
- Department of Chemistry, University of California, Berkeley, CA, USA
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Jessalyn A. DeVine
- Department of Chemistry, University of California, Berkeley, CA, USA
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Daniel M. Neumark
- Department of Chemistry, University of California, Berkeley, CA, USA
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
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2
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Yang T, Dangi BB, Thomas AM, Kaiser RI. Untangling the reaction dynamics of the silylidyne radical (SiH; X2Π) with acetylene (C2H2; X1Σg+). Chem Phys Lett 2016. [DOI: 10.1016/j.cplett.2016.05.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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3
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Yang T, Dangi BB, Maksyutenko P, Kaiser RI, Bertels LW, Head-Gordon M. Combined Experimental and Theoretical Study on the Formation of the Elusive 2-Methyl-1-silacycloprop-2-enylidene Molecule under Single Collision Conditions via Reactions of the Silylidyne Radical (SiH; X(2)Π) with Allene (H2CCCH2; X(1)A1) and D4-Allene (D2CCCD2; X(1)A1). J Phys Chem A 2015; 119:12562-78. [PMID: 26535955 DOI: 10.1021/acs.jpca.5b09773] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The crossed molecular beam reactions of the ground-state silylidyne radical (SiH; X(2)Π) with allene (H2CCCH2; X(1)A1) and D4-allene (D2CCCD2; X(1)A1) were carried out at collision energies of 30 kJ mol(-1). Electronic structure calculations propose that the reaction of silylidyne with allene has no entrance barrier and is initiated by silylidyne addition to the π electron density of allene either to one carbon atom (C1/C2) or to both carbon atoms simultaneously via indirect (complex forming) reaction dynamics. The initially formed addition complexes isomerize via two distinct reaction pathways, both leading eventually to a cyclic SiC3H5 intermediate. The latter decomposes through a loose exit transition state via an atomic hydrogen loss perpendicularly to the plane of the decomposing complex (sideways scattering) in an overall exoergic reaction (experimentally: -19 ± 13 kJ mol(-1); computationally: -5 ± 3 kJ mol(-1)). This hydrogen loss yields the hitherto elusive 2-methyl-1-silacycloprop-2-enylidene molecule (c-SiC3H4), which can be derived from the closed-shell cyclopropenylidene molecule (c-C3H2) by replacing a hydrogen atom with a methyl group and the carbene carbon atom by the isovalent silicon atom. The synthesis of the 2-methyl-1-silacycloprop-2-enylidene molecule in the bimolecular gas-phase reaction of silylidyne with allene enriches our understanding toward the formation of organosilicon species in the gas phase of the interstellar medium in particular via exoergic reactions of no entrance barrier. This facile route to 2-methyl-1-silacycloprop-2-enylidene via a silylidyne radical reaction with allene opens up a versatile approach to form hitherto poorly characterized silicon-bearing species in extraterrestrial environments; this reaction class might represent the missing link, leading from silicon-bearing radicals via organosilicon chemistry eventually to silicon-carbon-rich interstellar grains even in cold molecular clouds where temperatures are as low as 10 K.
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Affiliation(s)
- Tao Yang
- Department of Chemistry, University of Hawai'i at Manoa , Honolulu, Hawaii 96822, United States.,Department of Chemistry, University of California, Berkeley , Berkeley, California 94720, United States
| | - Beni B Dangi
- Department of Chemistry, University of Hawai'i at Manoa , Honolulu, Hawaii 96822, United States.,Department of Chemistry, University of California, Berkeley , Berkeley, California 94720, United States
| | - Pavlo Maksyutenko
- Department of Chemistry, University of Hawai'i at Manoa , Honolulu, Hawaii 96822, United States.,Department of Chemistry, University of California, Berkeley , Berkeley, California 94720, United States
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Manoa , Honolulu, Hawaii 96822, United States.,Department of Chemistry, University of California, Berkeley , Berkeley, California 94720, United States
| | - Luke W Bertels
- Department of Chemistry, University of Hawai'i at Manoa , Honolulu, Hawaii 96822, United States.,Department of Chemistry, University of California, Berkeley , Berkeley, California 94720, United States
| | - Martin Head-Gordon
- Department of Chemistry, University of Hawai'i at Manoa , Honolulu, Hawaii 96822, United States.,Department of Chemistry, University of California, Berkeley , Berkeley, California 94720, United States
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McCarthy MC, Baraban JH, Changala PB, Stanton JF, Martin-Drumel MA, Thorwirth S, Gottlieb CA, Reilly NJ. Discovery of a Missing Link: Detection and Structure of the Elusive Disilicon Carbide Cluster. J Phys Chem Lett 2015; 6:2107-2111. [PMID: 26266510 DOI: 10.1021/acs.jpclett.5b00770] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The rotational spectrum of the elusive but fundamentally important silicon carbide SiCSi has been detected using sensitive microwave techniques aided by high-level ab initio methods. Its equilibrium structure has been determined to very high precision using isotopic substitution and vibrational corrections calculated quantum-chemically: it is an isosceles triangle with a Si-C bond length of 1.693(1) Å, and an apex angle of 114.87(5)°. Now that all four Si(m)C(n) clusters with m + n = 3 have been observed experimentally, their structure and chemical bonding can be rigorously compared. Because Si2C is so closely linked to other Si-bearing molecules that have been detected in the evolved carbon star IRC+10216, it is an extremely promising candidate for detection with radio telescopes.
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Affiliation(s)
| | - Joshua H Baraban
- ‡Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - P Bryan Changala
- ¶JILA, National Institute of Standards and Technology, and Department of Physics, University of Colorado, Boulder, Colorado 80309, United States
| | - John F Stanton
- §Institute for Theoretical Chemistry, Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | | | - Sven Thorwirth
- ∥I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany
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5
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Truong NX, Savoca M, Harding DJ, Fielicke A, Dopfer O. Vibrational spectra and structures of SinC clusters (n = 3–8). Phys Chem Chem Phys 2015; 17:18961-70. [DOI: 10.1039/c5cp02588e] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The geometries of C-doped silicon clusters determined from infrared spectroscopy and computational chemistry reveal the stable Si3C unit as a common structural motif.
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Affiliation(s)
- Nguyen Xuan Truong
- Institut für Optik und Atomare Physik
- Technische Universität Berlin
- D-10623 Berlin
- Germany
| | - Marco Savoca
- Institut für Optik und Atomare Physik
- Technische Universität Berlin
- D-10623 Berlin
- Germany
| | - Dan J. Harding
- Institut für Physikalische Chemie
- Georg-August-Universität Göttingen
- D-37077 Göttingen
- Germany
- Department of Dynamics at Surfaces
| | - André Fielicke
- Institut für Optik und Atomare Physik
- Technische Universität Berlin
- D-10623 Berlin
- Germany
| | - Otto Dopfer
- Institut für Optik und Atomare Physik
- Technische Universität Berlin
- D-10623 Berlin
- Germany
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Savoca M, Lagutschenkov A, Langer J, Harding DJ, Fielicke A, Dopfer O. Vibrational Spectra and Structures of Neutral SimCn Clusters (m + n = 6): Sequential Doping of Silicon Clusters with Carbon Atoms. J Phys Chem A 2012; 117:1158-63. [DOI: 10.1021/jp305107f] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Marco Savoca
- Institut für Optik und
Atomare Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
| | - Anita Lagutschenkov
- Institut für Optik und
Atomare Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
| | - Judith Langer
- Institut für Optik und
Atomare Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
| | - Dan J. Harding
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin,
Germany
| | - André Fielicke
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin,
Germany
| | - Otto Dopfer
- Institut für Optik und
Atomare Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
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Garcia-Fernandez P, Bersuker IB, Boggs JE. Orbital disproportionation and spin crossover as a pseudo Jahn-Teller effect. J Chem Phys 2006; 125:104102. [PMID: 16999510 DOI: 10.1063/1.2346682] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
It is shown that in systems with electronic half-closed-shell configurations of degenerate orbitals, e(2) and t(3) (which have totally symmetric charge distribution), ground state distortions from high-symmetry geometries may occur due to a strong pseudo Jahn-Teller effect (PJTE) in the excited states, resulting also in a novel phenomenon of PJT-induced spin crossover. There is no JTE neither in the ground state term nor in the excited terms (including degenerate terms) of these configurations but a strong PJT mixing between two excited states [((1)E+(1)A) [cross-filled circle] e and ((2)T(1)+(2)T(2)) [cross-filled circle] e in the e(2) and t(3) cases, respectively] pushes down the lower term to cross the ground state of the undistorted system and to form the global minimum with a distorted geometry. The analysis of the electronic structure of this distorted configuration shows that it is accompanied by orbital disproportionation: instead of proportional population of all degenerate orbitals by one electron each (as in the ground state of the undistorted system that follows Hund's rule), two electrons with opposite spins occupy one orbital, resulting in transformations of the type (e(theta);e(epsilon))-->(e(theta)e(theta)) for e(2) and (t(x);t(y);t(z))-->(t(x);t(x);t(z)) for t(3) systems. Since the two geometry configurations, undistorted and distorted, appertain to different electronic terms that have different spin states, the formation of the global minimum with the distorted configuration is accompanied by a spin crossover. Distinguished from the known spin-crossover phenomenon in some transition metal compounds, the two states with different spin in the PJT-induced spin crossover have also different nuclear configurations, undistorted and distorted, that coexist with a relatively small energy difference. The change of configuration reduces significantly the rate of relaxation between the two states; the relaxation is further reduced by the lower spin-orbital coupling in the light-atom systems as compared with transition metal compounds. This means that there may be systems for which the switch between the two states (in both directions) under perturbations may be observed as a single-molecule phenomenon. Systems with half-closed-shell electronic configurations e(2) and t(3) are available in a variety of molecules from different classes, organic and inorganic; the theory is illustrated here by ab initio calculations for a series of molecular systems, including Si(3), Si(3)C, CuF(3), Na(3), Si(4), Na(4), Na(4) (-), and C(60) (3-), which are in agreement with the experimental data available.
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Affiliation(s)
- P Garcia-Fernandez
- Institute for Theoretical Chemistry, Chemistry and Biochemistry Department, The University of Texas at Austin, Austin, TX 78712-0165, USA.
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