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Manfred Winnewisser - One of the best experts on this subject based on the ideXlab platform.
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The Colorful World of Quasilinearity as Revealed by High Resolution Molecular Spectroscopy
Progress in Fourier Transform Spectroscopy, 1997Co-Authors: Sieghard Albert, Manfred Winnewisser, Brenda P. WinnewisserAbstract:The analysis of the mid infrared spectrum (1200–4000 cm-1) of Fulminic Acid yielded the identification of more than 110 new vibrational levels. Each assigned vibrational level shows interactions enhanced by the quasilinearity of the molecule HCNO. Most of the resonances can be classified into a network of resonance systems. This network can be built up with the help of the basic resonance systems 00002/00010, 00004/00100 and 00015/01000 that include Coriohs-type and Fermi-type resonances. In this paper the 00200/00104/00007/[00033] and 00114/00210/00202/01003/ [00017] resonance systems are discussed in detail.
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An ab initio study on the equilibrium structure and HCN bending potential energy function of Fulminic Acid
Chemical Physics Letters, 1996Co-Authors: Jacek Koput, Brenda P. Winnewisser, Manfred WinnewisserAbstract:Abstract The molecular parameters of Fulminic Acid, HNCO, have been determined in large-scale ab initio calculations using the coupled cluster method, CCSD(T), and basis sets of double to quadruple zeta quality. With the largest basis set employed. cc-pVQZ, the equilibrium structure of the molecule was found to be slightly bent, with the parameters r( HC ) = 1.0615 A , r( CN ) = 1.1648 A , r( NO ) = 1.2025 A , ∠( HCN ) = 165.13°, ∠( NCO ) = 176.58° . The potential energy function for the large-amplitude HCN bending motion was determined to be anharmonic, with a barrier to linearity of the HCNO chain of only 7 cm −1 .
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Analysis of the Coriolis Resonance System (00002)/(00010) in Four Isotopomers of Fulminic Acid
Journal of Molecular Spectroscopy, 1996Co-Authors: Kastriot Islami, Jürgen Preusser, Roland Schermaul, Brenda P. Winnewisser, Manfred WinnewisserAbstract:Abstract This study follows an analogous treatment of data for H 13 C 14 NO (K. Islami, B. P. Winnewisser, J. Preusser, and M. Winnewisser, J. Mol. Spectrosc. 176, xxx–xxx (1996)). The model used for the analysis of the Coriolis resonance (00002)/(00010) was extended by G. Wagner, B. P. Winnewisser, M. Winnewisser, and K. Sarka, J. Mol. Spectrosc. 162, 82–119 (1993). In addition to the interaction between the vibrational levels ( v 1 v 2 v 3 v 4 v 5 ) k = (00002) 0 e and (00010) 1 e , an interaction between the levels (00002) 2 e , f and (00010) 1 e , f was included. However, the correlation between the Coriolis parameters describing the two interactions and their correlation with the l -type doubling parameters do not allow a simultaneous fit of both parameters. If the values of both Coriolis parameters are stepped manually, the standard deviation forms a surface. The minimum of the surface of the standard deviation has the form of a shallow valley which leads to ambiguous Coriolis parameters. The aim of this article is to illuminate and compare the ambiguity of the two Coriolis parameters for the four isotopomers H 12 C 14 NO, H 13 C 14 NO, H 12 C 15 NO, and H 13 C 15 NO using contour graphs which represent a projection onto a two-dimensional coordinate system of the surface of the standard deviation as a function of the two Coriolis parameters.
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analysis of the coriolis resonance system 00002 00010 in four isotopomers of Fulminic Acid
Journal of Molecular Spectroscopy, 1996Co-Authors: Kastriot Islami, Jürgen Preusser, Roland Schermaul, Brenda P. Winnewisser, Manfred WinnewisserAbstract:Abstract This study follows an analogous treatment of data for H 13 C 14 NO (K. Islami, B. P. Winnewisser, J. Preusser, and M. Winnewisser, J. Mol. Spectrosc. 176, xxx–xxx (1996)). The model used for the analysis of the Coriolis resonance (00002)/(00010) was extended by G. Wagner, B. P. Winnewisser, M. Winnewisser, and K. Sarka, J. Mol. Spectrosc. 162, 82–119 (1993). In addition to the interaction between the vibrational levels ( v 1 v 2 v 3 v 4 v 5 ) k = (00002) 0 e and (00010) 1 e , an interaction between the levels (00002) 2 e , f and (00010) 1 e , f was included. However, the correlation between the Coriolis parameters describing the two interactions and their correlation with the l -type doubling parameters do not allow a simultaneous fit of both parameters. If the values of both Coriolis parameters are stepped manually, the standard deviation forms a surface. The minimum of the surface of the standard deviation has the form of a shallow valley which leads to ambiguous Coriolis parameters. The aim of this article is to illuminate and compare the ambiguity of the two Coriolis parameters for the four isotopomers H 12 C 14 NO, H 13 C 14 NO, H 12 C 15 NO, and H 13 C 15 NO using contour graphs which represent a projection onto a two-dimensional coordinate system of the surface of the standard deviation as a function of the two Coriolis parameters.
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Nuclear Quadrupole Hyperfine Structure of the Direct /-Type Transitions of the Fulminic Acid Isotopomers H12C14N16O and H13C14N16O
Zeitschrift für Naturforschung A, 1996Co-Authors: Jürgen Preusser, Manfred WinnewisserAbstract:The direct I- type transitions of H133C14N16O in the vibrational states (υ4,υ5) = (01) and (03) were measured in the frequency range from 18 to 40 GHz. These transitions show a nuclear quadrupole hyperfine structure caused by the 14N nucleus, which could partially be resolved at Doppler-limited resolution. The analogous transitions of the parent species. H12C14N16O, were remeasured. They displayed a very similar hyperfine structure, also partially resolved. The hyperfine patterns of both H12C14N16O and H13C14N16O were analysed by means of contour fitting s to the absorption profiles. The parameter ηseQq, which is responsible for the splittings, is determined to be 645(20) kHz for the vibrational state (01) and 890(44) kHz for the vibrational state (03) for H12C14N16O and 642(32) kHz for (01) and 898(22) kHz for (03) for H13C14N16O. This unexpectedly large splitting parameter for states involving the large amplitude motion υ5 (HCN bending) is discussed as another consequence of the quasilinearity of Fulminic Acid, in view of the fact that the analogous transitions for the vibrational state (10) (NCO bending) do not split or even show a significant line broadening at the resolution used for the present measurements
Brenda P. Winnewisser - One of the best experts on this subject based on the ideXlab platform.
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The Colorful World of Quasilinearity as Revealed by High Resolution Molecular Spectroscopy
Progress in Fourier Transform Spectroscopy, 1997Co-Authors: Sieghard Albert, Manfred Winnewisser, Brenda P. WinnewisserAbstract:The analysis of the mid infrared spectrum (1200–4000 cm-1) of Fulminic Acid yielded the identification of more than 110 new vibrational levels. Each assigned vibrational level shows interactions enhanced by the quasilinearity of the molecule HCNO. Most of the resonances can be classified into a network of resonance systems. This network can be built up with the help of the basic resonance systems 00002/00010, 00004/00100 and 00015/01000 that include Coriohs-type and Fermi-type resonances. In this paper the 00200/00104/00007/[00033] and 00114/00210/00202/01003/ [00017] resonance systems are discussed in detail.
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An ab initio study on the equilibrium structure and HCN bending potential energy function of Fulminic Acid
Chemical Physics Letters, 1996Co-Authors: Jacek Koput, Brenda P. Winnewisser, Manfred WinnewisserAbstract:Abstract The molecular parameters of Fulminic Acid, HNCO, have been determined in large-scale ab initio calculations using the coupled cluster method, CCSD(T), and basis sets of double to quadruple zeta quality. With the largest basis set employed. cc-pVQZ, the equilibrium structure of the molecule was found to be slightly bent, with the parameters r( HC ) = 1.0615 A , r( CN ) = 1.1648 A , r( NO ) = 1.2025 A , ∠( HCN ) = 165.13°, ∠( NCO ) = 176.58° . The potential energy function for the large-amplitude HCN bending motion was determined to be anharmonic, with a barrier to linearity of the HCNO chain of only 7 cm −1 .
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Analysis of the Coriolis Resonance System (00002)/(00010) in Four Isotopomers of Fulminic Acid
Journal of Molecular Spectroscopy, 1996Co-Authors: Kastriot Islami, Jürgen Preusser, Roland Schermaul, Brenda P. Winnewisser, Manfred WinnewisserAbstract:Abstract This study follows an analogous treatment of data for H 13 C 14 NO (K. Islami, B. P. Winnewisser, J. Preusser, and M. Winnewisser, J. Mol. Spectrosc. 176, xxx–xxx (1996)). The model used for the analysis of the Coriolis resonance (00002)/(00010) was extended by G. Wagner, B. P. Winnewisser, M. Winnewisser, and K. Sarka, J. Mol. Spectrosc. 162, 82–119 (1993). In addition to the interaction between the vibrational levels ( v 1 v 2 v 3 v 4 v 5 ) k = (00002) 0 e and (00010) 1 e , an interaction between the levels (00002) 2 e , f and (00010) 1 e , f was included. However, the correlation between the Coriolis parameters describing the two interactions and their correlation with the l -type doubling parameters do not allow a simultaneous fit of both parameters. If the values of both Coriolis parameters are stepped manually, the standard deviation forms a surface. The minimum of the surface of the standard deviation has the form of a shallow valley which leads to ambiguous Coriolis parameters. The aim of this article is to illuminate and compare the ambiguity of the two Coriolis parameters for the four isotopomers H 12 C 14 NO, H 13 C 14 NO, H 12 C 15 NO, and H 13 C 15 NO using contour graphs which represent a projection onto a two-dimensional coordinate system of the surface of the standard deviation as a function of the two Coriolis parameters.
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analysis of the coriolis resonance system 00002 00010 in four isotopomers of Fulminic Acid
Journal of Molecular Spectroscopy, 1996Co-Authors: Kastriot Islami, Jürgen Preusser, Roland Schermaul, Brenda P. Winnewisser, Manfred WinnewisserAbstract:Abstract This study follows an analogous treatment of data for H 13 C 14 NO (K. Islami, B. P. Winnewisser, J. Preusser, and M. Winnewisser, J. Mol. Spectrosc. 176, xxx–xxx (1996)). The model used for the analysis of the Coriolis resonance (00002)/(00010) was extended by G. Wagner, B. P. Winnewisser, M. Winnewisser, and K. Sarka, J. Mol. Spectrosc. 162, 82–119 (1993). In addition to the interaction between the vibrational levels ( v 1 v 2 v 3 v 4 v 5 ) k = (00002) 0 e and (00010) 1 e , an interaction between the levels (00002) 2 e , f and (00010) 1 e , f was included. However, the correlation between the Coriolis parameters describing the two interactions and their correlation with the l -type doubling parameters do not allow a simultaneous fit of both parameters. If the values of both Coriolis parameters are stepped manually, the standard deviation forms a surface. The minimum of the surface of the standard deviation has the form of a shallow valley which leads to ambiguous Coriolis parameters. The aim of this article is to illuminate and compare the ambiguity of the two Coriolis parameters for the four isotopomers H 12 C 14 NO, H 13 C 14 NO, H 12 C 15 NO, and H 13 C 15 NO using contour graphs which represent a projection onto a two-dimensional coordinate system of the surface of the standard deviation as a function of the two Coriolis parameters.
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ROTATIONAL AND ROVIBRATIONAL SPECTRA OF H13C15NO IN THE SPECTRAL REGIONS 18-40 GHZ, 110-440 GHZ, AND 170-1850 CM-1
Journal of Molecular Spectroscopy, 1996Co-Authors: Jürgen Preusser, Roland Schermaul, Brenda P. Winnewisser, Manfred WinnewisserAbstract:Abstract The pure rotational and rovibrational spectra of H 13 C 15 NO, an isotopically substituted species of the quasilinear molecule Fulminic Acid, were investigated by means of microwave, millimeter-wave, and Fourier-transform infrared spectroscopy. The pure rotational spectra were measured in the spectral regions from 18 to 40 GHz and from 110 to 440 GHz. Direct l -type transitions were also observed in the region from 18 to 40 GHz. Approximately 500 line positions with microwave accuracy (10–40 kHz) were obtained in these spectral regions. The rovibrational spectrum was recorded in four segments covering the range from the far-infrared to the mid-infrared, 170–1850 cm −1 , using a Bruker IFS 120 HR interferometer with resolutions between 0.0017 and 0.0028 cm −1 . In total, more than 13 000 infrared lines were assigned. Power series constants for the assigned transitions are given. Spectroscopic parameters of an effective Hamiltonian for linear molecules were adjusted for the vibrational states ( v 1 v 2 v 3 v 4 v 5 ) = (00000), (00001), (00002), (00003), (00004), (00010), (00011), (00100), and (00101). Several accidental resonances, known from other isotopomers of Fulminic Acid, were analyzed and the isotopic dependence of the resonance effects compared. The treatment of a calibration problem, which became obvious when data from the different infrared spectra were fitted simultaneously, is discussed.
Robert Flammang - One of the best experts on this subject based on the ideXlab platform.
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Formation of Cumulenes, Triple-Bonded, and Related Compounds by Flash Vacuum Thermolysis of Five-Membered Heterocycles
ChemInform, 2010Co-Authors: Gloria I. Yranzo, Robert Flammang, José Elguero, Curt WentrupAbstract:Flash vacuum thermolysis of a large variety of heterocyclic compounds is a useful means of production of ketenes, ketenimines, thioketenes, allenes, iminopropadienones, bis(imino)propadienes, iminopropadienethiones, carbodiimides, isothiocyanates, acetylenes, Fulminic Acid, nitrile imines and nitrile ylides, nitriles, cyanamides, cyanates, and other compounds, often in preparatively useful yields.
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Formation of Cumulenes, Triple‐Bonded, and Related Compounds by Flash Vacuum Thermolysis of Five‐Membered Heterocycles
European Journal of Organic Chemistry, 2001Co-Authors: Gloria I. Yranzo, José Elguero, Robert FlammangAbstract:Flash vacuum thermolysis of a large variety of heterocyclic compounds is a useful means of production of ketenes, ketenimines, thioketenes, allenes, iminopropadienones, bis(imino)propadienes, iminopropadienethiones, carbodiimides, isothiocyanates, acetylenes, Fulminic Acid, nitrile imines and nitrile ylides, nitriles, cyanamides, cyanates, and other compounds, often in preparatively useful yields.
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Formation and identification of ionized and neutral cumulenes, RNCCCNH, by tandem mass spectrometry
Organic Mass Spectrometry, 1993Co-Authors: Robert Flammang, Sophie Laurent, M. Flammang-barbieux, Curt WentrupAbstract:Using a combination of mass spectrometric techniques, it is shown that 5-amino-4-cyanoisoxazole molecular ions (1+.), lose isocyanic Acid HNC=O, not Fulminic Acid, HC=N --> 0. Metastable ion fragmentations (unimolecular and collision induced) and deuterium-labelling experiments are in agreement with the formation of a cumulenic structure, HN=C=C=C=NH (3a+.). The hitherto unreported molecules HNCCCNH are also shown to be stable when formed in the low-pressure gas phase of the mass spectrometer by using the technique of neutralization-reionization mass spectrometry. The arguments developed for the characterization of 3a+. have also been extended to the methylated and phenylated analogues 3b+. and 3c+. [RN=C=C=C=NH+., R = CH3 or C6H5]. On flash-vacuum pyrolysis at 700-degrees-C, 1 also loses HN=C=O producing the cumulene 3a, which is in turn readily tautomerized into malononitrile via wall collisions.
David L. Cooper - One of the best experts on this subject based on the ideXlab platform.
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Modern valence-bond description of chemical reaction mechanisms: the 1,3-dipolar addition of diazomethane to ethene.
The Journal of organic chemistry, 2001Co-Authors: Joshua J. Blavins, Peter B. Karadakov, David L. CooperAbstract:The electronic mechanism for the gas-phase concerted 1,3-dipolar cycloaddition of diazomethane (CH2N2) to ethene (C2H4) is described through spin-coupled (SC) calculations at a sequence of geometries along the intrinsic reaction coordinate obtained at the MP2/6-31G(d) level of theory. It is shown that the bonding rearrangements occurring during the course of this reaction follow a heterolytic pattern, characterized by the movement of three well-identifiable orbital pairs, which are initially responsible for the π bond in ethene and the C−N π bond and one of the N−N π bonds in diazomethane and are retained throughout the entire reaction path from reactants to product. Taken together with our previous SC study of the electronic mechanism of the 1,3-dipolar cycloaddition of Fulminic Acid (HCNO) to ethyne (C2H2) (Theor. Chim. Acc. 1998, 100, 222), the results of the present work suggest strongly that most gas-phase concerted 1,3-dipolar cycloaddition reactions can be expected to follow a heterolytic mechanism...
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Modern valence-bond description of chemical reaction mechanisms: the 1,3-dipolar addition of Fulminic Acid to ethyne
Theoretical Chemistry Accounts, 1998Co-Authors: Peter B. Karadakov, David L. Cooper, Joseph GerrattAbstract:The electronic mechanism for the gas-phase 1,3-dipolar cycloaddition of Fulminic Acid (HCNO) to ethyne is studied through a combination of modern valence-bond theory in its spin-coupled (SC) form and intrinsic reaction coordinate calculations utilizing a complete-active-space self-consistent field wavefunction. It is shown that the concerted reaction follows a “heterolytic” route, during which three orbital pairs corresponding to three distinct bonds in the reactants (an in-plane π bond in ethyne, and a C-N and an N-O in-plane bond in HCNO) shift simultaneously to create the two new bonds closing the isoxazole ring and a nitrogen lone pair. The analysis of the SC wavefunction strongly suggests that the reacting system remains nonaromatic throughout the most important part of the cycloaddition process. This investigation provides the first demonstration of an alternative SC description of a bond rearrangement, achieved through the movement of singlet orbital pairs through space, during which at least one of the orbitals within a pair becomes completely detached from the atomic centre with which it is associated initially and ends up localized about another centre.
Marius Lewerenz - One of the best experts on this subject based on the ideXlab platform.
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Electric and magnetic properties of the four most stable CHNO isomers from ab initio CCSD(T) studies
Journal of Chemical Physics, 2017Co-Authors: Marko Mladenović, M. Elhiyani, Marius LewerenzAbstract:Electric and magnetic properties obtained from CCSD(T) /(aug-)cc-pCVXZ (X=T, Q, or 5) electronic structure calculations are reported for isocyanic Acid, HNCO, cyanic Acid, HOCN, Fulminic Acid, HCNO, and isoFulminic Acid, HONC, in their ground electronic states. Comparison of the theoretical results with the available experimentally derived values shows very satisfactory agreement. The new data should be helpful for the identification of these molecules due to characteristic hyperfine structure patterns in their microwave spectra. A brief discussion of the electronic structure properties, based on the electric field gradients, Mulliken population analysis of the total electron density, and molecular orbitals, is provided for the four CHNO isomers and the related HCN/HNC system.
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Equilibrium structure and energetics of CHNO isomers: Steps towards ab initio rovibrational spectra of quasi-linear molecules
2007Co-Authors: Mirjana Mladenović, Marius LewerenzAbstract:We report large-scale electronic structure calculations for Fulminic Acid, HCNO, isocyanic Acid, HNCO, and cyanic Acid, HOCN, in their ground electronic states. The coupled cluster CCSD(T) method including all single and double excitations and a perturbative term for connected triple substitutions is used in conjunction with large correlation consistent polarized valence basis sets of the form cc-pVXZ (X = 2-6) and cc-pCVXZ (X = 2-5). Our results show the importance of including all electrons in the correlation treatment to obtain a converged molecular structure for the extremely floppy HCNO molecule and the correct energetics of the three isomers. All-electron correlation calculations and frozen core calculations with very large basis sets clearly converge towards a linear electronic minimum for HCNO surrounded by a very large flat region of the potential energy surface for hydrogen bending motions. For each of the three isomers we have computed the barrier to linearity along the respective minimum energy path and several spectroscopic parameters and equilibrium rotational constants.
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AB INITIO ELECTRONIC AND ROVIBRATIONAL STRUCTURE OF Fulminic Acid
2007Co-Authors: Mirjana Mladenović, Marius LewerenzAbstract:Author Institution: Laboratoire de Chimie Theorique,; Universite de Marne la Vallee, 5, boulevard Descartes,; Champs sur Marne, 77454 Marne la Vallee Cedex 2, France
