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Marro EA, Folster CP, Press EM, Im H, Ferguson JT, Siegler MA, Klausen RS. Stereocontrolled Syntheses of Functionalized cis- and trans-Siladecalins. J Am Chem Soc 2019; 141:17926-17936. [PMID: 31600060 DOI: 10.1021/jacs.9b09902] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report the synthesis of both diastereomers of an all-silicon analog of decalin. Carbocyclic decalin is a ubiquitous bicyclic structural motif. The siladecalin synthesis provides materials functionalized with either Si-Ph or Si-H groups, versatile entry points for further chemical diversification. The synthesis of silicon-stereogenic silanes is significantly less precedented than the synthesis of asymmetric carbon centers, and strategies for control of relative stereochemistry in oligosilanes are hardly described. This study offers insights of potential generality, such as the epimerization of the cis-isomer to the thermodynamically downhill trans-isomer via a hypothesized pentavalent intermediate. Decalin is a classic example in the conformational analysis of organic ring systems, and the carbocyclic diastereomers have highly divergent conformational profiles. Like the carbocycle, we observe different conformational properties in cis- and trans-siladecalins with consequences for NMR spectroscopy, optical properties, and vibrational spectroscopy. This study showcases the utility of targeted synthesis for preparing complex and functionalized polycyclic silanes.
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Affiliation(s)
- Eric A Marro
- Department of Chemistry , Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States
| | - Carlton P Folster
- Department of Chemistry , Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States
| | - Eric M Press
- Department of Chemistry , Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States
| | - Hoyeon Im
- Department of Chemistry , Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States
| | - John T Ferguson
- Department of Chemistry , Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States
| | - Maxime A Siegler
- Department of Chemistry , Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States
| | - Rebekka S Klausen
- Department of Chemistry , Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States
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2
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Purkait TK, Press EM, Marro EA, Siegler MA, Klausen RS. Low-Energy Electronic Transition in SiB Rings. Organometallics 2018. [DOI: 10.1021/acs.organomet.8b00804] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tapas K. Purkait
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| | - Eric M. Press
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| | - Eric A. Marro
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| | - Maxime A. Siegler
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| | - Rebekka S. Klausen
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
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3
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Hanulikova B, Kuritka I. Conformational disorder in polysilylenes studied theoretically on tetramers. COMPUT THEOR CHEM 2017. [DOI: 10.1016/j.comptc.2017.10.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Su TA, Li H, Klausen RS, Kim NT, Neupane M, Leighton JL, Steigerwald ML, Venkataraman L, Nuckolls C. Silane and Germane Molecular Electronics. Acc Chem Res 2017; 50:1088-1095. [PMID: 28345881 DOI: 10.1021/acs.accounts.7b00059] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
This Account provides an overview of our recent efforts to uncover the fundamental charge transport properties of Si-Si and Ge-Ge single bonds and introduce useful functions into group 14 molecular wires. We utilize the tools of chemical synthesis and a scanning tunneling microscopy-based break-junction technique to study the mechanism of charge transport in these molecular systems. We evaluated the fundamental ability of silicon, germanium, and carbon molecular wires to transport charge by comparing conductances within families of well-defined structures, the members of which differ only in the number of Si (or Ge or C) atoms in the wire. For each family, this procedure yielded a length-dependent conductance decay parameter, β. Comparison of the different β values demonstrates that Si-Si and Ge-Ge σ bonds are more conductive than the analogous C-C σ bonds. These molecular trends mirror what is seen in the bulk. The conductance decay of Si and Ge-based wires is similar in magnitude to those from π-based molecular wires such as paraphenylenes However, the chemistry of the linkers that attach the molecular wires to the electrodes has a large influence on the resulting β value. For example, Si- and Ge-based wires of many different lengths connected with a methyl-thiomethyl linker give β values of 0.36-0.39 Å-1, whereas Si- and Ge-based wires connected with aryl-thiomethyl groups give drastically different β values for short and long wires. This observation inspired us to study molecular wires that are composed of both π- and σ-orbitals. The sequence and composition of group 14 atoms in the σ chain modulates the electronic coupling between the π end-groups and dictates the molecular conductance. The conductance behavior originates from the coupling between the subunits, which can be understood by considering periodic trends such as bond length, polarizability, and bond polarity. We found that the same periodic trends determine the electric field-induced breakdown properties of individual Si-Si, Ge-Ge, Si-O, Si-C, and C-C bonds. Building from these studies, we have prepared a system that has two different, alternative conductance pathways. In this wire, we can intentionally break a labile, strained silicon-silicon bond and thereby shunt the current through the secondary conduction pathway. This type of in situ bond-rupture provides a new tool to study single molecule reactions that are induced by electric fields. Moreover, these studies provide guidance for designing dielectric materials as well as molecular devices that require stability under high voltage bias. The fundamental studies on the structure/function relationships of the molecular wires have guided the design of new functional systems based on the Si- and Ge-based wires. For example, we exploited the principle of strain-induced Lewis acidity from reaction chemistry to design a single molecule switch that can be controllably switched between two conductive states by varying the distance between the tip and substrate electrodes. We found that the strain intrinsic to the disilaacenaphthene scaffold also creates two state conductance switching. Finally, we demonstrate the first example of a stereoelectronic conductance switch, and we demonstrate that the switching relies crucially on the electronic delocalization in Si-Si and Ge-Ge wire backbones. These studies illustrate the untapped potential in using Si- and Ge-based wires to design and control charge transport at the nanoscale and to allow quantum mechanics to be used as a tool to design ultraminiaturized switches.
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Affiliation(s)
- Timothy A. Su
- Columbia University, Department of Chemistry, New York, New York 10027, United States
| | - Haixing Li
- Columbia University, Department of Applied Physics
and Applied Math, New York, New York 10027, United States
| | - Rebekka S. Klausen
- Johns Hopkins University, Department of Chemistry, Baltimore, Maryland 21228, United States
| | - Nathaniel T. Kim
- Columbia University, Department of Chemistry, New York, New York 10027, United States
| | - Madhav Neupane
- Columbia University, Department of Chemistry, New York, New York 10027, United States
| | - James L. Leighton
- Columbia University, Department of Chemistry, New York, New York 10027, United States
| | | | - Latha Venkataraman
- Columbia University, Department of Chemistry, New York, New York 10027, United States
- Columbia University, Department of Applied Physics
and Applied Math, New York, New York 10027, United States
| | - Colin Nuckolls
- Columbia University, Department of Chemistry, New York, New York 10027, United States
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5
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Kanazawa Y, Tsuji H, Ehara M, Fukuda R, Casher DL, Tamao K, Nakatsuji H, Michl J. Electronic Transitions in Conformationally Controlled Peralkylated Hexasilanes. Chemphyschem 2016; 17:3010-3022. [DOI: 10.1002/cphc.201600633] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Indexed: 11/08/2022]
Affiliation(s)
- Yuki Kanazawa
- SOKENDAI The Graduate University for Advanced Studies, Nishigonaka, Myodaiji Okazaki 444–8585 Japan
- Institute for Molecular Science and Research Center for Computational Science, Nishigonaka, Myodaiji Okazaki 444–8585 Japan
| | - Hayato Tsuji
- International Research Center for Elements Science (IRCELS) Institute for Chemical Research Kyoto University, Uji Kyoto 611-0011 Japan
- Department of Chemistry Faculty of Science Kanagawa University 2946 Tsuchiya Hiratsuka Kanagawa 259–1293 Japan
| | - Masahiro Ehara
- SOKENDAI The Graduate University for Advanced Studies, Nishigonaka, Myodaiji Okazaki 444–8585 Japan
- Institute for Molecular Science and Research Center for Computational Science, Nishigonaka, Myodaiji Okazaki 444–8585 Japan
- Elements Strategy Initiative for Catalysts and Batteries (ESICB) Kyoto University Kyoto 615–8520 Japan
| | - Ryoichi Fukuda
- Elements Strategy Initiative for Catalysts and Batteries (ESICB) Kyoto University Kyoto 615–8520 Japan
| | - Deborah L. Casher
- Department of Chemistry and Biochemistry University of Colorado at Boulder Boulder Colorado 80309-0215 USA
| | - Kohei Tamao
- International Research Center for Elements Science (IRCELS) Institute for Chemical Research Kyoto University, Uji Kyoto 611-0011 Japan
- RIKEN 2-1 Hirosawa Saitama 351-0198 Japan
| | - Hiroshi Nakatsuji
- Quantum Chemistry Research Institute Goryo Oohara 1–36, Nishikyo-ku Kyoto 615–8245 Japan
| | - Josef Michl
- Department of Chemistry and Biochemistry University of Colorado at Boulder Boulder Colorado 80309-0215 USA
- Institute of Organic Chemistry and Biochemistry Academy of Sciences of the Czech Republic Flemingovo nám. 2 16610 Prague Czech Republic
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6
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The structure and phase transitions of crystalline polydimethylsilane [Me2Si] n revisited. Russ Chem Bull 2015. [DOI: 10.1007/s11172-014-0770-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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7
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Tsuji H, Fogarty HA, Ehara M, Fukuda R, Casher DL, Tamao K, Nakatsuji H, Michl J. Electronic transitions in conformationally controlled tetrasilanes with a wide range of SiSiSiSi dihedral angles. Chemistry 2014; 20:9431-41. [PMID: 25043859 DOI: 10.1002/chem.201403495] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Indexed: 11/08/2022]
Abstract
Unlike π-electron chromophores, the peralkylated n-tetrasilane σ-electron chromophore resembles a chameleon in that its electronic spectrum changes dramatically as its silicon backbone is twisted almost effortlessly from the syn to the anti conformation (changing the SiSiSiSi dihedral angle ω from 0 to 180°). A combination of UV absorption, magnetic circular dichroism (MCD), and linear dichroism (LD) spectroscopy on conformationally controlled tetrasilanes 1-9, which cover fairly evenly the full range of angles ω, permitted a construction of an experimental correlation diagram for three to four lowest valence electronic states. The free chain tetrasilane n-Si4 Me10 (10), normally present as a mixture of three enantiomeric conformer pairs of widely different angles ω, has also been included in our study. The spectral trends are interpreted in terms of avoided crossings of 1B with 2B and 2A with 3A states, in agreement with SAC-CI calculations on the excited states of 1-7 and conformers of 10.
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Affiliation(s)
- Hayato Tsuji
- International Research Center for Elements Science (IRCELS), Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan); Present address: Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku,Tokyo 113-0033 (Japan)
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Schwabedissen J, Lane PD, Masters SL, Hassler K, Wann DA. Gas-phase structures of sterically crowded disilanes studied by electron diffraction and quantum chemical methods: 1,1,2,2-tetrakis(trimethylsilyl)disilane and 1,1,2,2-tetrakis(trimethylsilyl)dimethyldisilane. Dalton Trans 2014; 43:10175-82. [PMID: 24873858 DOI: 10.1039/c4dt00628c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The gas-phase structures of the disilanes 1,1,2,2-tetrakis(trimethylsilyl)disilane [(Me3Si)2HSiSiH(SiMe3)2] (1) and 1,1,2,2-tetrakis(trimethylsilyl)dimethyldisilane [(Me3Si)2MeSiSiMe(SiMe3)2] (2) have been determined by density functional theoretical calculations and by gas electron diffraction (GED) employing the SARACEN method. For each of 1 and 2 DFT calculations revealed four C2-symmetric conformers occupying minima on the respective potential-energy surfaces; three conformers were estimated to be present in sufficient quantities to be taken into account when fitting the GED data. For (Me3Si)2RSiSiR(SiMe3)2 [R = H (1), CH3 (2)] the lowest energy conformers were found by GED to have RSiSiR dihedral angles of 87.7(17)° for 1 and -47.0(6)° for 2. For each of 1 and 2 the presence of bulky and flexible trimethylsilyl groups dictates many aspects of the geometric structures in the gas phase, with the molecules often adopting structures that reduce steric strain.
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Affiliation(s)
- Jan Schwabedissen
- Fakultät für Chemie, Anorganische Chemie und Strukturchemie, Universitätsstr. 25, 33615 Bielefeld, Germany
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9
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MacLeod MK, Michl J. Five Stereoactive Orbitals on Silicon: Charge and Spin Localization in the n-Si4Me10(-•) Radical Anion by Trigonal Bipyramidalization. J Phys Chem Lett 2013; 4:1649-1653. [PMID: 26282973 DOI: 10.1021/jz400417k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
RIUMP2/def2-TZVPPD calculations show that in addition to its usual conformation with charge and spin delocalized over the Si backbone, the isolated Si4Me10(-•) radical anion also has isomeric conformations with localized charge and spin. A structure with localization on a terminal Si atom has been examined in detail. In vacuum, it is calculated to lie 11.5 kcal/mol higher in energy than the charge-and-spin delocalized conformation, and in water the difference is as little as 1.6 kcal/mol. According to natural orbital and localized orbital analyses, the charge-and-spin-carrying terminal Si atom uses five stereoactive hybrid orbitals in a trigonal bipyramidal geometry. Four are built mostly from 3s and 3p atomic orbitals (AOs) and are used to attach a Si3(CH3)7 and three CH3 groups, whereas the larger equatorial fifth orbital is constructed from 4s and 4p AOs and acts as a nonbonding (radical) hybrid orbital with an occupancy of about 0.65 e.
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Affiliation(s)
- Matthew K MacLeod
- †Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - Josef Michl
- †Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States
- ‡Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám., 2, 166 10 Praha 6, Czech Republic
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Wallner A, Emanuelsson R, Baumgartner J, Marschner C, Ottosson H. Coupling of Disilane and Trisilane Segments Through Zero, One, Two, and Three Disilanyl Bridges in Cyclic and Bicyclic Saturated Carbosilanes. Organometallics 2013. [DOI: 10.1021/om3006678] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Andreas Wallner
- Department
of Chemistry-BMC, Uppsala University, Box 576, SE-75123 Uppsala, Sweden
| | - Rikard Emanuelsson
- Department
of Chemistry-BMC, Uppsala University, Box 576, SE-75123 Uppsala, Sweden
| | - Judith Baumgartner
- Institut für Anorganische
Chemie, Technische Universität Graz, A-8010 Graz, Austria
| | - Christoph Marschner
- Institut für Anorganische
Chemie, Technische Universität Graz, A-8010 Graz, Austria
| | - Henrik Ottosson
- Department
of Chemistry-BMC, Uppsala University, Box 576, SE-75123 Uppsala, Sweden
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Stueger H, Albering J, Flock M, Fuerpass G, Mitterfellner T. cis,cis-1,3,5-Trihydroxynonamethylcyclohexasilane: A Cyclopolysilane with Unusual Properties. Organometallics 2011. [DOI: 10.1021/om200025n] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Harald Stueger
- Institute of Inorganic Chemistry, Graz University of Technology, Stremayrgasse 9, A-8010 Graz, Austria
| | - Joerg Albering
- Institute of Inorganic Chemistry, Graz University of Technology, Stremayrgasse 9, A-8010 Graz, Austria
| | - Michaela Flock
- Institute of Inorganic Chemistry, Graz University of Technology, Stremayrgasse 9, A-8010 Graz, Austria
| | - Gottfried Fuerpass
- Institute of Inorganic Chemistry, Graz University of Technology, Stremayrgasse 9, A-8010 Graz, Austria
| | - Thomas Mitterfellner
- Institute of Inorganic Chemistry, Graz University of Technology, Stremayrgasse 9, A-8010 Graz, Austria
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Bande A, Michl J. Conformational dependence of sigma-electron delocalization in linear chains: permethylated oligosilanes. Chemistry 2009; 15:8504-8517. [PMID: 19658142 DOI: 10.1002/chem.200901521] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The effects of sigma-electron delocalization on optical properties of saturated linear chains of permethylated oligosilanes are strongly conformation dependent. We analyze the origin of the conformational dependence of the energies of molecular orbitals and of electronic excitations in simple intuitively understandable terms by using a first-order approximation to the Hückel version of the "Ladder C" model. The analysis is supported by comparison with results of numerical calculations from time-dependent density functional theory, which agree well with experiment. To facilitate the comparison, a simple procedure has been developed that defines the overall and local fractional sigma and pi characters of a backbone molecular orbital and a fractional overall and local sigma sigma* and sigma pi* characters of an excited state for any conformation of a linear chain.
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Affiliation(s)
- Annika Bande
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0215, USA
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Piqueras MC, Crespo R, Michl J. Interpretation of the electronic spectra of four disilanes. J Phys Chem A 2008; 112:13095-101. [PMID: 18821735 DOI: 10.1021/jp804677v] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Time-dependent density functional theory (TD-DFT/B3LYP(AC)/cc-pVTZ/cc-pVTZ/6-311G//MP2/cc-pVTZ/cc-pVTZ/6-31G**) has been used to compute vertical excitation energies and oscillator strengths of the six low-lying excited states of four peralkylated disilanes, hexamethyldisilane (1), hexa-tert-butyldisilane (2), 1,6-disila[4.4.4]propellane (3), and 1,7-disila[5.5.5]propellane (4). The results provide an accurate interpretation of the reported UV absorption spectra of 1-4 in solution, and for 1 also in the gas phase up to 62,000 cm(-1). The excellent agreement of the calculated with the available experimental energies and oscillator strengths, and with magnetic circular (MCD) and linear (LD) dichroism, gives us confidence that the method will be useful for dependable interpretation of the electronic spectra of longer oligosilanes. Although the disilane chromophore finds itself in quite different environments in 1-4, its fundamental characteristics remain the same, with one important exception. In all four compounds, the first valence excited state is due to an electron promotion from the sigma(1) HOMO to the pi(1)* orbital, and the second valence excited state to a promotion from the sigma(1) HOMO to the sigma(1)* orbital. Surprisingly, however, it is only in 2, which has an extraordinarily long SiSi bond, that the terminating sigma(1)* orbital is the sigma*(SiSi) antibond, as anticipated, and the sigma sigma* transition has the expected very high oscillator strength. In 1, 3, and 4, the sigma*(SiSi) antibonding orbital is high in energy and does not play any role in low-energy excitations. Instead, the terminating orbital of the sigma(1)sigma(1)* excitation is represented by Si-alkyl antibonds, combined symmetrically with respect to rotation around the SiSi axis and antisymmetrically with respect to operations that interchange the two Si atoms. The common assumption that the characteristic intense sigma sigma* transitions of longer peralkylated oligosilanes extrapolate to the lowest sigma sigma* transition in common peralkylated disilanes is incorrect, and only the weak sigma pi* transitions extrapolate simply.
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Affiliation(s)
- Mari Carmen Piqueras
- Departament de Química Física, Universitat de València, Dr. Moliner 50, E-46100 Burjassot, Spain
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KARATSU T. Photochemistry and photophysics of organomonosilane and oligosilanes: Updating their studies on conformation and intramolecular interactions. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C-PHOTOCHEMISTRY REVIEWS 2008. [DOI: 10.1016/j.jphotochemrev.2008.06.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Sandström N, Piqueras MC, Ottosson H, Crespo R. Electronic excitations of 1,4-disilyl-substituted 1,4-disilabicycloalkanes: a MS-CASPT2 study of the influence of cage size. J Phys Chem A 2007; 111:2804-10. [PMID: 17388376 DOI: 10.1021/jp070010n] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We present a multistate complete active space second-order perturbation theory computational study aimed to predict the low-lying electronic excitations of four compounds that can be viewed as two disilane units connected through alkane bridges in a bicyclic cage. The analysis has focused on 1,4-disilyl-1,4-disilabicyclo[2.2.1]heptane (1a), 1,4-bis(trimethylsilyl)-1,4-disilabicyclo[2.2.1]heptane (1b), 1,4-disilyl-1,4-disilabicyclo[2.1.1]hexane (2a), and 1,4-bis(trimethylsilyl)-1,4-disilabicyclo[2.1.1]hexane (2b). The aim has been to find out the nature of the lowest excitations with significant oscillator strengths and to investigate how the cage size affects the excitation energies and the strengths of the transitions. Two different substituents on the terminal silicon atoms (H and CH3) were used in order to investigate the end group effects. The calculations show that the lowest allowed excitations are of the same character as that found in disilanes but now red-shifted. As the cage size is reduced from a 1,4-disilabicyclo[2.2.1]heptane to a 1,4-disilabicyclo[2.1.1]hexane, the Si...Si through-space distance decreases from approximately 2.70 to 2.50 A and the lowest allowed transitions are red-shifted by up to 0.9 eV, indicating increased interaction between the two Si-Si bonds. The first ionization potential, which corresponds to ionization from the Si-Si sigma orbitals, is lower in 1b and 2b than in Si2Me6 by approximately 0.9 and 1.2 eV, respectively. Moreover, 1b and 2b, which have methyl substituents at the terminal Si atoms, have slightly lower excitation energies than the analogous species 1a and 2a.
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Affiliation(s)
- Niclas Sandström
- Department of Biochemistry and Organic Chemistry, Box 576, Uppsala University, 751 23 Uppsala, Sweden
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Crespo R, Piqueras MC, Michl J. Electronic excitation in a syn-tetrasilane: 1,1,2,2,3,3, 4,4-octamethyltetrasilacyclopentane. Theor Chem Acc 2007. [DOI: 10.1007/s00214-007-0246-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Shibano Y, Sasaki M, Tsuji H, Araki Y, Ito O, Tamao K. Conformation effect of oligosilane linker on photoinduced electron transfer of tetrasilane-linked zinc porphyrin–[60]fullerene dyads. J Organomet Chem 2007. [DOI: 10.1016/j.jorganchem.2006.05.062] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Fogarty HA, Ottosson H, Michl J. Calculation of Relative Energies of Permethylated Oligosilane Conformers in Vapor and in Alkane Solution. J Phys Chem B 2006; 110:25485-95. [PMID: 17165997 DOI: 10.1021/jp064643y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The geometries of 35 conformers of Me(SiMe2)nMe (n = 4, 1; n = 5, 2; n = 6, 3; n = 7, 4) were optimized at the MP2/VTDZ level, and CCSD(T) single-point calculations were done at three MP2/VTDZ conformer geometries of 1. The relative ground-state energies of the conformers of 1-4 in the gas phase were obtained from the MP2/VTDZ electronic energy, zero-point vibrational energy, and thermal corrections at 0, 77, and 298 K. Relative energies in an alkane solvent at 77 and 298 K were obtained by the addition of solvation energies, obtained from the SM5.42R model. The calculated energies of 26 of the conformers (n = 4-6) have been least-squares fitted to a set of 15 additive increments associated with each Si-Si bond conformation and each pair of adjacent bond conformations, with mean deviations of 0.06-0.20 kcal/mol. An even better fit for the energies of 24 conformers (mean deviations, 0.01-0.09 kcal/mol) has been obtained with a larger set of 19 increments, which also contained contributions from selected combinations of conformations of three adjacent bonds. The utility of the additive increments for the prediction of relative conformer energies in the gas phase and in solution has been tested on the remaining nine conformers (n = 6, 7). With the improved increment set, the average deviation from the SM5.42R//MP2 results for solvated conformers at 298 K was 0.18 kcal/mol, and the maximum error was 0.98 kcal/mol.
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Affiliation(s)
- Heather A Fogarty
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, USA
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Tsuji H, Sasaki M, Shibano Y, Toganoh M, Kataoka T, Araki Y, Tamao K, Ito O. Photoinduced Electron Transfer of Dialkynyldisilane-Linked Zinc Porphyrin–[60]Fullerene Dyad. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2006. [DOI: 10.1246/bcsj.79.1338] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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20
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Dzambaski A, Baumgartner J, Flock M, Tekautz G, Hassler K, Hassler W. Unusual conformational properties of 1,3-dimethyl-1,1,3,3-tetrakis(trimethylsilyl)trisilane: A preparative, X-ray, Raman spectroscopic and ab initio study. J Organomet Chem 2006. [DOI: 10.1016/j.jorganchem.2006.04.026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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21
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Tekautz G, Binter A, Hassler K, Flock M. Chair, Boat and Twist Conformation of Dodecamethylcyclohexasilane and Undecamethylcyclohexasilane: A Combined DFT and Raman Spectroscopic Study. Chemphyschem 2006; 7:421-9. [PMID: 16411262 DOI: 10.1002/cphc.200500417] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The conformations of dodecamethylcyclohexasilane Si6Me12 and undecamethylcyclohexasilane Si6Me11H have been investigated by ab initio calculations employing the B3LYP density functional with a 6-31+G(d) basis set. Local minima as well as transition structures were calculated with imposed symmetry constraints. For Si6Me12, three unique minima, which correspond to the chair, twist and boat conformations were located with relative zero-point-vibration-corrected energies of 0.0, 7.8 and 11.4 kJ mol(-1). A half-chair conformation with four coplanar silicon atoms connects the chair and twisted minima via an energy barrier of 16.0 and 8.2 kJ mol(-1), respectively. A second transition structure with a barrier of 3.9/0.3 kJ mol(-1) connects the twist with the boat structure. Solution Raman spectra of Si6(CH3)12 and Si6(CD3)12 fully corroborate these results. Below -40 degrees C, the symmetric SiSi ring breathing vibration is a single line, which develops a shoulder (originating from the twist conformer) at longer wavelengths whose intensity increases with increasing temperature. From a Van't Hoff plot, the chair/twist enthalpy difference is 6.6+/-1.5 kJ mol(-1) for Si6(CH3)12 and 6.0+/-1.5 kJ mol(-1) for Si6(CD3)12, which is in reasonable agreement with the ab initio results. Due to the low barrier, the boat conformation cannot be observed, because either the lowest torsional vibration level lies above it or a rapid interconversion between the twist and boat conformations occurs, resulting in averaged Raman spectra. For Si6Me11H, six local minima were located. The chair with the hydrogen atom in the axial position (axial chair) is the global minimum, followed by the equatorial chair (+1.9 kJ mol(-1)) and the three twist conformers (+5.3, +8.0 and +8.1 kJ mol(-1)). The highest local minimum (+11.9 kJ mol(-1)) is a C(s) symmetric boat with the hydrogen atom in the equatorial position. Two possible pathways for the chair-to-chair interconversion with barriers of 13.9 and 14.5 kJ mol(-1) have been investigated. The solution Raman spectra in the SiSi ring breathing region clearly show that below -50 degrees C only the axial and equatorial chairs are present, with an experimental deltaH-value of 0.46 kJ mol(-1). With increasing temperature a shoulder develops which is attributed to the combined twist conformers. The experimental deltaH-value is 6.9 kJ mol(-1), in good agreement with the ab initio results. Due to the low interconversion barriers, the various twist conformers cannot be detected separately.
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Affiliation(s)
- Günter Tekautz
- Institute of Inorganic Chemistry, University of Technology, Stremayrgasse 16, 8010 Graz (Austria)
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22
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Marschner C, Baumgartner J, Wallner A. Structurally and conformationally defined small methyl polysilanes. Dalton Trans 2006:5667-74. [PMID: 17146531 DOI: 10.1039/b613642g] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Possessing the property of sigma-bond electron delocalisation, polysilanes are a class of compounds with unique properties. In recent years major progress has been achieved in the theoretical understanding and the synthesis of polysilanes. Much insight into the connection between conformation and electronic properties has been gained from studies of defined small polysilane molecules. The transition from Wurtz type coupling reactions to the stepwise construction of polysilane molecules employing silyl anions as key intermediates has permitted access to defined compounds with a higher degree of structural complexity. Besides this, several methods have been developed to control the conformational properties and thus gain control over the electronic properties of polysilanes.
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Affiliation(s)
- Christoph Marschner
- Institut für Anorganische Chemie, Technische Universität Graz, Stremayrgasse 16, A-8010, Graz, Austria.
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23
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Sanji T, Kato M, Tanaka M. Self-Assembly of Oligosilane−Cyclodextrin Complexes Using Host-Stabilized π Interactions. Macromolecules 2005. [DOI: 10.1021/ma047587c] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Takanobu Sanji
- Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan, and Department of Pure and Applied Chemistry, Tokyo University of Science, Noda 278-8510, Japan
| | - Masako Kato
- Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan, and Department of Pure and Applied Chemistry, Tokyo University of Science, Noda 278-8510, Japan
| | - Masato Tanaka
- Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan, and Department of Pure and Applied Chemistry, Tokyo University of Science, Noda 278-8510, Japan
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24
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Fogarty HA, Imhof R, Michl J. Magnetic circular dichroism of peralkylated tetrasilane conformers. Proc Natl Acad Sci U S A 2004; 101:10517-22. [PMID: 15249672 PMCID: PMC489969 DOI: 10.1073/pnas.0403209101] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Magnetic circular dichroism (MCD) of five peralkylated tetrasilanes (1-5) conformationally constrained to angles ranging from nearly 0 degrees to 180 degrees and of the open chain tetrasilane Si(4)Me(10) (6) shows a clear conformational dependence and permits the detection of previously hidden transitions. In the tetrasilane CH(2)Si(4)Me(8) (1), with the smallest dihedral angle, comparison of MCD with absorption spectra reveals four low-energy electronic transitions. In the tetrasilanes 2-4, three distinct transitions are apparent. In tetrasilanes 5 and 6, MCD reveals the very weak transition that has been predicted to be buried under the first intense peak and to which the anomalous thermochromism of 6 and other short-chain oligosilanes has been attributed.
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Affiliation(s)
- Heather A Fogarty
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0215, USA
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25
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Tsuji H, Fukazawa A, Yamaguchi S, Toshimitsu A, Tamao K. all-anti-Pentasilane: Conformation Control of Oligosilanes Based on the Bis(tetramethylene)-Tethered Trisilane Unit. Organometallics 2004. [DOI: 10.1021/om049695t] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Hayato Tsuji
- International Research Center for Elements Science (IRCELS), Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Aiko Fukazawa
- International Research Center for Elements Science (IRCELS), Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Shigehiro Yamaguchi
- International Research Center for Elements Science (IRCELS), Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Akio Toshimitsu
- International Research Center for Elements Science (IRCELS), Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Kohei Tamao
- International Research Center for Elements Science (IRCELS), Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
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26
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Mallesha H, Tsuji H, Tamao K. UV Absorption and Mass Spectra of n-Alkylsilyl End-Capped Anti,Cisoid-Alternating Oligosilanes up to Docosasilane (Si22). Organometallics 2004. [DOI: 10.1021/om034307t] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Honnaiah Mallesha
- International Research Center for Elements Science, Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Hayato Tsuji
- International Research Center for Elements Science, Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Kohei Tamao
- International Research Center for Elements Science, Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
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27
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28
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Tsuji H, Michl J, Tamao K. Recent experimental and theoretical aspects of the conformational dependence of UV absorption of short chain peralkylated oligosilanes. J Organomet Chem 2003. [DOI: 10.1016/s0022-328x(03)00162-1] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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29
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Tsuji H, Terada M, Toshimitsu A, Tamao K. Sigmasigma* transition in anti,cisoid alternating oligosilanes: clear-cut evidence for suppression of conjugation effect by a cisoid turn. J Am Chem Soc 2003; 125:7486-7. [PMID: 12812467 DOI: 10.1021/ja034500e] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
On the basis of the UV absorption spectra of the anti,cisoid alternating oligosilanes, the first experimental clear-cut evidence was presented for the generally accepted idea that the sigma conjugation in polysilanes does not effectively extend through a tetrasilane fragment with a small dihedral angle such as a cisoid turn.
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Affiliation(s)
- Hayato Tsuji
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
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30
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Piqueras MC, Crespo R, Michl J. The Transoid, Ortho, and Gauche Conformers of Decamethyl-n-tetrasilane, n-Si4Me10: Electronic Transitions in the Multistate Complete Active Space Second-Order Perturbation Theory Description. J Phys Chem A 2003. [DOI: 10.1021/jp022675p] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mari Carmen Piqueras
- Departament de Química Física i Institut de Ciència Molecular, Universitat de València, Dr. Moliner 50, E-46100 Burjassot (Valencia), Spain
| | - Raül Crespo
- Departament de Química Física i Institut de Ciència Molecular, Universitat de València, Dr. Moliner 50, E-46100 Burjassot (Valencia), Spain
| | - Josef Michl
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215
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31
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Rooklin DW, Schepers T, Raymond-Johansson MK, Michl J. Time-dependent density functional theory treatment of the first UV absorption band in all-transoid permethyloligosilanes SinMe2n + 2 (n = 2-8, 10). Photochem Photobiol Sci 2003; 2:511-7. [PMID: 12803073 DOI: 10.1039/b302087h] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The TD B3LYP/6-311G(d,p) method slightly overestimates the excitation energies of the first UV absorption band of the all-transoid conformers of SinMe2n + 2 (n = 2-8, 10), deduced from temperature-dependent measurements on conformer mixtures in hydrocarbon solvents, by a nearly constant amount (approximately 2000 cm-1). The TD B3LYP/6-31G(d) results are less satisfactory. The first band is calculated to be due to a sigma pi * excitation in Si2Me6 and to a superposition of overlapping sigma sigma * and sigma pi * excitations in the longer oligosilanes. The sigma pi * excitation is calculated to lie a little below the sigma sigma * excitation up to Si4Me10, the two transitions are nearly degenerate in Si5Me12, and the sigma sigma * excitation drops increasingly below the sigma pi * as the chain length is extended. The dipole strength of the sigma sigma * excitation grows by 4.8 D2 (D = debye) per added SiSi bond (more slowly up to n = 5) and the calculation overestimates it by a factor of about three. The sigma pi * excitation is computed to carry no or almost no oscillator strength, but as noted earlier by others, its presence is critical for the interpretation of the observed thermochromism. Upon cooling below room temperature, the first absorption maximum is blue-shifted in short chains and red-shifted in long chains. Unlike the prior investigators, we attribute the blue shift to the disappearance of hot bands built on the sigma pi * origin using intensity borrowing sigma-pi mixing vibrations (b1 in Si3Me8). As usual, the red shift is attributed to the disappearance of twisted conformers, which have higher calculated sigma sigma * excitation energies.
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Affiliation(s)
- David W Rooklin
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0215, USA
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32
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Effects of oxygen atom in the side chain on physical and optical properties of dodecapentoxypentasilane. Chem Phys Lett 2003. [DOI: 10.1016/s0009-2614(03)00078-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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33
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Piqueras MC, Merchán M, Crespo R, Michl J. Conformational Effects on the Ultraviolet Absorption Spectrum ofn-Tetrasilane: Multistate Complete Active Space Second-Order Perturbation Theory Treatment†. J Phys Chem A 2002. [DOI: 10.1021/jp020460+] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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34
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PIQUERAS MARICARMEN, CRESPO RAÜL, MICHL JOSEF. Multiconfigurational second-order perturbation calculation of the electronic absorption spectrum of trisilane, Si3H8. Mol Phys 2002. [DOI: 10.1080/00268970110095147] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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35
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Fogarty HA, Tsuji H, David DE, Ottosson CH, Ehara M, Nakatsuji H, Tamao K, Michl J. Peralkylated Tetrasilanes: Conformational Dependence of the Photoelectron Spectrum. J Phys Chem A 2002. [DOI: 10.1021/jp013458b] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Heather A. Fogarty
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, Institute for Chemical Research, Kyoto University, Uji 611-0011, Japan, and Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 606-8501, Japan
| | - Hayato Tsuji
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, Institute for Chemical Research, Kyoto University, Uji 611-0011, Japan, and Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 606-8501, Japan
| | - Donald E. David
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, Institute for Chemical Research, Kyoto University, Uji 611-0011, Japan, and Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 606-8501, Japan
| | - Carl-Henrik Ottosson
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, Institute for Chemical Research, Kyoto University, Uji 611-0011, Japan, and Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 606-8501, Japan
| | - Masahiro Ehara
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, Institute for Chemical Research, Kyoto University, Uji 611-0011, Japan, and Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 606-8501, Japan
| | - Hiroshi Nakatsuji
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, Institute for Chemical Research, Kyoto University, Uji 611-0011, Japan, and Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 606-8501, Japan
| | - Kohei Tamao
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, Institute for Chemical Research, Kyoto University, Uji 611-0011, Japan, and Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 606-8501, Japan
| | - Josef Michl
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, Institute for Chemical Research, Kyoto University, Uji 611-0011, Japan, and Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 606-8501, Japan
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36
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Sanji T, Takase K, Sakurai H. Helical-sense programming through polysilane-poly(triphenylmethyl methacrylate) block copolymers. J Am Chem Soc 2001; 123:12690-1. [PMID: 11741439 DOI: 10.1021/ja0167250] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- T Sanji
- Department of Pure and Applied Chemistry, Science University of Tokyo, Chiba 278-8510, Japan
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37
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Zink R, Tekautz G, Kleewein A, Hassler K. Gauche, Ortho, Transoid andAnti Conformations of the Tetrasilanes SiMe3SiX2SiX2SiMe3 (X=H, F, Cl, Br, I): A Computational and Vibrational Spectroscopic Study. Chemphyschem 2001; 2:377-83. [DOI: 10.1002/1439-7641(20010618)2:6<377::aid-cphc377>3.0.co;2-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2000] [Revised: 01/22/2001] [Indexed: 11/11/2022]
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38
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Tsuji H, Toshimitsu A, Tamao K, Michl J. UV, MCD, and LD Spectra of a Conformationally Constrained ortho-Tetrasilane: Support for the Avoided Crossing Model of Conformational Effects on Excited States. J Phys Chem A 2001. [DOI: 10.1021/jp010792z] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hayato Tsuji
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Akio Toshimitsu
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Kohei Tamao
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Josef Michl
- Department of Chemistry and Biochemistry, University of Colorado at Boulder, Boulder, Colorado 80309-0215
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39
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Michl J, West R. Conformations of linear chains. Systematics and suggestions for nomenclature. Acc Chem Res 2000; 33:821-3. [PMID: 11123880 DOI: 10.1021/ar0001057] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
There are six categories of calculated favored dihedral angles in linear M(n)X(2n+2) chains. The Prelog-Klyne nomenclature is not helpful for classifying them, and we propose the following labels and symbols: A, anti, reserved for torsional angles within a few degrees of 180 degrees; T, transoid, omega approximately 165 degrees; D, deviant, omega approximately 150 degrees; O, ortho, omega approximately 90 degrees; G, gauche, omega approximately 60 degrees; C, cisoid, omega approximately 40 degrees. With the exception of C, all of these categories have been observed in alkanes, perfluoroalkanes, or oligosilanes.
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Affiliation(s)
- J Michl
- Department of Chemistry University of Wisconsin, Madison, Wisconsin 53706-1396, USA
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40
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41
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42
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43
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Tamao K, Tsuji H, Terada M, Asahara M, Yamaguchi S, Toshimitsu A. Conformation Control of Oligosilanes Based on Configurationally Constrained Bicyclic Disilane Units. Angew Chem Int Ed Engl 2000. [DOI: 10.1002/1521-3757(20000915)112:18<3425::aid-ange3425>3.0.co;2-w] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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44
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45
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Crespo R, Merchán M, Michl J. Electronic Excitation in a Saturated Chain: An MS-CASPT2 Treatment of the Anti Conformer of n-Tetrasilane. J Phys Chem A 2000. [DOI: 10.1021/jp001973o] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Raül Crespo
- Departament de Química Física, Universitat de València, Dr. Moliner 50, Burjassot, E-46100 València, Spain
| | - Manuela Merchán
- Departament de Química Física, Universitat de València, Dr. Moliner 50, Burjassot, E-46100 València, Spain
| | - Josef Michl
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215
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46
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Fogarty H, Ottosson CH, Michl J. The five favored backbone conformations of n -Si 4 Et 10 : cisoid , gauche , ortho , deviant , and transoid. ACTA ACUST UNITED AC 2000. [DOI: 10.1016/s0166-1280(00)00416-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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47
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Ottosson CH, Michl J. Conformers of n-Si6Me14: Ab Initio, Molecular Mechanics, and Additive Increment Methods. J Phys Chem A 2000. [DOI: 10.1021/jp994054a] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Carl-Henrik Ottosson
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215
| | - Josef Michl
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215
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48
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Zink R, Magnera TF, Michl J. Transoid, Ortho, and Gauche Conformers of n-Si4Cl10: Raman and Mid-IR Matrix-Isolation Spectra. J Phys Chem A 2000. [DOI: 10.1021/jp994017j] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Robert Zink
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215
| | - Thomas F. Magnera
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215
| | - Josef Michl
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215
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49
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Molecular structure and conformational composition of decamethyl-n-tetrasilane, Si4Me10, by gas electron diffraction and density functional theory calculations. J Organomet Chem 2000. [DOI: 10.1016/s0022-328x(99)00650-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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50
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Hummeltenberg R, Hassler K, Uhlig F. A Raman spectroscopic study of the rotational isomerism of linear permethylated stannylsilanes Me3Sn(SiMe2)nSnMe3 with n=1, 2, 3, 4. J Organomet Chem 1999. [DOI: 10.1016/s0022-328x(99)00514-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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