Summaries of FY 1988 Research in the Chemical Sciences
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A Comprehensive Investigation on the Formation of Organo-Sulfur Molecules in Dark Clouds Via Neutral-Neutral Reactions
A&A 395, 1031–1044 (2002) Astronomy DOI: 10.1051/0004-6361:20021328 & c ESO 2002 Astrophysics A comprehensive investigation on the formation of organo-sulfur molecules in dark clouds via neutral-neutral reactions M. Yamada1, Y. Osamura1, and R. I. Kaiser2;? 1 Department of Chemistry, Rikkyo University, 3-34-1 Nishi-ikebukuro, Tokyo 171-8501, Japan 2 Department of Chemistry, University of York, YO10 5DD, UK Received 11 June 2002 / Accepted 9 September 2002 Abstract. Fifteen reactions on the doublet HCnS and singlet/triplet H2CnS(n = 1; 2) potential energy surfaces have been investi- gated theoretically via electronic structure calculations to unravel the formation of hydrogen deficient, sulfur bearing molecules via bimolecular reactions of two neutral species in cold molecular clouds. Various barrierless reaction pathways to synthe- size astronomically observed CnS and hitherto undetected HCnS(n = 1; 2) isomers are offered. These data present important 2 2 guidance to search for rotational transitions of the elusive thioformyl HCS(X A0) and thioketenyl HCCS(X Π) radicals in the interstellar medium. Key words. astrochemistry – ISM: molecules – molecular processes – methods: miscellaneous 1. Introduction terminated counterparts HCnSandCnSH have not been de- tected in the interstellar medium yet. However, these molecules Untangling the synthetic routes to form sulfur-carrying might represent the missing source of molecular-bound sul- molecules in the interstellar medium is a significant instru- fur in the interstellar medium. Hydrogen deficient organosul- ment to understand the chemical evolution and physical con- 2 2 fur molecules like HCS(X A0) and HCCS(X Π) resemble also ditions in star forming regions and in circumstellar envelopes important reaction intermediates which could lead to sulfur (Minh & van Dishoeck 2000). -
What Is the Shape of the Helium Trimer? a Comparison with the Neon and Argon Trimers Dario Bressanini* and Gabriele Morosi
ARTICLE pubs.acs.org/JPCA What Is the Shape of the Helium Trimer? A Comparison with the Neon and Argon Trimers Dario Bressanini* and Gabriele Morosi Dipartimento di Scienze Chimiche e Ambientali, Universita' dell'Insubria, Via Lucini 3, 22100 Como, Italy ABSTRACT: Despite its apparent simplicity and extensive theoretical investiga- tions, the issue of what is the shape of the helium trimer is still debated in the literature. After reviewing previous conflicting interpretations of computational studies, we introduce the angleÀangle distribution function as a tool to discuss in a simple way the shape of any trimer. We compute this function along with many different geometrical distributions using variational and diffusion Monte Carlo methods. We compare them with the corresponding ones for the neon and argon fl trimers. Our analysis shows that while Ne3 and Ar3 uctuate around an 4 equilibrium structure that is an equilateral triangle, He3 shows an extremely broad angleÀangle distribution function, and all kinds of three-atom configura- 4 tions must be taken into account in its description. Classifying He3 as either equilateral or linear or any other particular shape, as was done in the past, is not sensible, because in this case the intuitive notion of equilibrium structure is ill defined. Our results could help the interpretation of future experiments aimed at measuring the geometrical properties of the helium trimer. ’ INTRODUCTION candidate for the Efimov effect, first discussed in nuclear physics. 1 Weakly bound van der Waals noble gases clusters in the last The recent paper of Kolganova et al. provides a nice review of the literature of this field of research. -
H2CS) and Its Thiohydroxycarbene Isomer (HCSH
A chemical dynamics study on the gas phase formation of thioformaldehyde (H2CS) and its thiohydroxycarbene isomer (HCSH) Srinivas Doddipatlaa, Chao Hea, Ralf I. Kaisera,1, Yuheng Luoa, Rui Suna,1, Galiya R. Galimovab, Alexander M. Mebelb,1, and Tom J. Millarc,1 aDepartment of Chemistry, University of Hawai’iatManoa, Honolulu, HI 96822; bDepartment of Chemistry and Biochemistry, Florida International University, Miami, FL 33199; and cSchool of Mathematics and Physics, Queen’s University Belfast, Belfast BT7 1NN, Northern Ireland, United Kingdom Edited by Stephen J. Benkovic, The Pennsylvania State University, University Park, PA, and approved August 4, 2020 (received for review March 13, 2020) Complex organosulfur molecules are ubiquitous in interstellar molecular sulfur dioxide (SO2) (21) and sulfur (S8) (22). The second phase clouds, but their fundamental formation mechanisms have remained commences with the formation of the central protostars. Tempera- largely elusive. These processes are of critical importance in initiating a tures increase up to 300 K, and sublimation of the (sulfur-bearing) series of elementary chemical reactions, leading eventually to organo- molecules from the grains takes over (20). The subsequent gas-phase sulfur molecules—among them potential precursors to iron-sulfide chemistry exploits complex reaction networks of ion–molecule and grains and to astrobiologically important molecules, such as the amino neutral–neutral reactions (17) with models postulating that the very acid cysteine. Here, we reveal through laboratory experiments, first sulfur–carbon bonds are formed via reactions involving methyl electronic-structure theory, quasi-classical trajectory studies, and astro- radicals (CH3)andcarbene(CH2) with atomic sulfur (S) leading to chemical modeling that the organosulfur chemistry can be initiated in carbonyl monosulfide and thioformaldehyde, respectively (18). -
UV-Spectrum of Thioformaldehyde-S-Oxide
Electronic Supplementary Material (ESI) for Chemical Communications This journal is © The Royal Society of Chemistry 2013 Matrix Isolation and Spectroscopic Properties • of the Methylsulfinyl Radical CH3(O)S [a] [b] [b] Hans Peter Reisenauer,* Jaroslaw Romanski, Grzegorz Mloston,* Peter R. Schreiner[a] [a] Justus-Liebig University, Institute of Organic Chemistry, Heinrich-Buff-Ring 58, D-35392 Giessen, Fax: (+49) 641-99-34209; E-mail: [email protected] [b] University of Lodz, Section of Heteroorganic Compounds, Tamka 12, PL-91-403 Lodz, Fax: (+48) (42) 665 51 62; E-mail: [email protected] Supplementary Information Table S1. Experimental (Ar, 10 K) and computed (AE-CCSD(T)/cc-pVTZ, harmonic approximation, no scaling) the IR spectra of 3. 13 3 C-3 D3-3 a b a b a b Sym. Approx. Band Position (Intensity) Band Position (Intensity) Band Position (Intensity) Mode Computation Experiment Computation Experiment Computation Experiment a’’ CH str. 3151.3 (2.1) 2995.4 3139.3 (2.1) n.o. 2336.4 (1.2) 2247.2 a’ CH str. 3149.3 (4.1) (vw) 3137.5 (4.0) n.o. 2334.5 (2.2) (vw) 2919.4 2095.5 a’ CH str. 3065.6 (4.3) 3062.7 (4.5) n.o. 2194.2 (1.4) (vw) (vw) CH 1062.8 a’ 3 1477.4 (6.5) 1417.1 (w) 1474.8 (6.6) 1414.6 (w) 1028.7 (s) def. (17.3) CH a’’ 3 1464.4 (7.8) 1405.2 (w) 1461.7 (7.8) 1401.4 (w) 1058.5 (3.7) 1025.6 (w) def. -
Thermal Averaging of the Indirect Nuclear Spin-Spin Coupling Constants of Ammonia: the Importance of the Large Amplitude Inversion Mode Andrey Yachmenev, Sergei N
Thermal averaging of the indirect nuclear spin-spin coupling constants of ammonia: The importance of the large amplitude inversion mode Andrey Yachmenev, Sergei N. Yurchenko, Ivana Paidarová, Per Jensen, Walter Thiel, and Stephan P. A. Sauer Citation: J. Chem. Phys. 132, 114305 (2010); doi: 10.1063/1.3359850 View online: https://doi.org/10.1063/1.3359850 View Table of Contents: http://aip.scitation.org/toc/jcp/132/11 Published by the American Institute of Physics Articles you may be interested in Accurate ab initio vibrational energies of methyl chloride The Journal of Chemical Physics 142, 244306 (2015); 10.1063/1.4922890 Automatic differentiation method for numerical construction of the rotational-vibrational Hamiltonian as a power series in the curvilinear internal coordinates using the Eckart frame The Journal of Chemical Physics 143, 014105 (2015); 10.1063/1.4923039 Theoretical rotation-vibration spectrum of thioformaldehyde The Journal of Chemical Physics 139, 204308 (2013); 10.1063/1.4832322 High-level ab initio potential energy surfaces and vibrational energies of H2CS The Journal of Chemical Physics 135, 074302 (2011); 10.1063/1.3624570 A highly accurate ab initio potential energy surface for methane The Journal of Chemical Physics 145, 104305 (2016); 10.1063/1.4962261 Ro-vibrational averaging of the isotropic hyperfine coupling constant for the methyl radical The Journal of Chemical Physics 143, 244306 (2015); 10.1063/1.4938253 THE JOURNAL OF CHEMICAL PHYSICS 132, 114305 ͑2010͒ Thermal averaging of the indirect nuclear spin-spin coupling constants of ammonia: The importance of the large amplitude inversion mode Andrey Yachmenev,1 Sergei N. -
Structural Features of the Carbon-Sulfur Chemical Bond: a Semi-Experimental Perspective Supporting Information
Structural features of the carbon-sulfur chemical bond: a semi-experimental perspective Supporting Information Emanuele Penocchio, Marco Mendolicchio, Nicola Tasinato, and Vincenzo Barone∗ Scuola Normale Superiore, Pisa, Italy E-mail: [email protected] ∗To whom correspondence should be addressed 1 In Table 1 we focus on molecules reported in Table 2 of the main article and compare reference SE equilibrium parameters with ab-initio predictions obtained with B3LYP/SNSD, B2PLYP/VTZ, M06-2X, and BHandH model chemistries. β In Table 2, experimental rotational constants, ∆Bvib calculated at B3LYP/SNSD and B2PLYP/VTZ β levels of theory, and ∆Bel calculated at B3LYP/AVTZ level are reported for all the species discussed in the main text. Table 1: Comparison between reference SE equilibrium parameters and ab-initio ones ob- tained using functionals with a different amount of Hartree-Fock exchange (see main text). Distances in A,˚ angles in degrees. Atom numbering as in Figure 2 of the main work. SEa re re B3LYP/SNSD B2PLYP/VTZ M06-2X/VTZ BHandH/VTZ SE { Sulfur chains { isothiocyanic acid r(S-C) 1:5832 1:5744 1:5713 1:5588 1:5678(7) r(C-N) 1:2091 1:2047 1:1922 1:179 1:2047(9) r(N-H) 1:0102 1:0035 1:0035 0:9974 1:0070(9) a(S-C-N) 173:77 173:95 174:81 175:42 172:23(18) a(H-N-C) 129:67 131:50 134:72 137:28 129:75(5) thioformaldehyde r(S-C) 1:6227 1:6135 1:60089 1:58782 1:6093(1) r(C-H) 1:0918 1:0859 1:08702 1:0849 1:0854(2) a(H-C-S) 121:95 122:01 122:025 121:964 121:73(2) thioketene r(S-C) 1:5724 1:5623 1:5546 1:5426 1:5556(4) r(C-C) 1:3107 1:3082 1:3021 1:2899 1:3107(5) r(C-H) 1:0863 1:0801 1:0811 1:0793 1:0806(1) a(C-C-H) 120:66 120:46 120:31 129:34 120:15(1) propadienethione r(S1-C2) 1:5876 1:5776 1:5673 1:5546 1:5715(15) r(C2-C3) 1:2722 1:2691 1:2679 1:2571 1:2702(18) r(C3-C4) 1:3223 1:3191 1:3119 1:3003 1:3228(9) r(C4-H) 1:0905 1:0848 1:0851 1:0832 1:0842(3) a(H-C4-C3) 121:80 121:68 121:48 121:49 121:20(2) 2 β β Table 2: Experimental rotational constants, ∆Bvib, and ∆Bel are reported for all the species discussed in the main text. -
Version 038 – Exam 2 – Mccord – (53130) 1 This Print-Out Should
Version038–Exam2–McCord–(53130) 1 This print-out should have 31 questions. 3. sp3 Multiple-choice questions may continue on the next column or page – find all choices 4. Pure pz orbitals are used in bonding. before answering. 5. sp3d McCord CH301tt Explanation: The structure is b b b This exam is only for b O McCord’s Tues/Thur CH301 class. C If Quest works properly, you should be able H3C CH3 to see your score for this exam by 11:30 PM tonight. Do realize however that Quest has 003 10.0 points been taking up to 8 hours to get through the Which of the molecules b b b grading, so your score might appear bit by bit. b O I will post an announcement on our web page I) and/or Quest when I feel like all bubblesheets H H have been graded. b b b b b b Cl PLEASE carefully bubble in your UTEID and Version Number! We av- II) b b B b b b erage about 20-30 students per exam that b b b b Cl Clb b misbubble this information. Get it right! b b b b b b b b III) b Cl Cl b b b b 001 10.0 points contains polar covalent bonds but is NOT Choose the species that is incorrectly matched itself a polar molecule? with electronic geometry about the central atom. 1. III only 1. CF4 : tetrahedral 2. II and III only 2. BeBr2 : linear 3. I and II only 3. H2O : tetrahedral 4. -
Fantasy Versus Reality in Fragment-Based Quantum Chemistry
The Journal PERSPECTIVE of Chemical Physics scitation.org/journal/jcp Fantasy versus reality in fragment-based quantum chemistry Cite as: J. Chem. Phys. 151, 170901 (2019); doi: 10.1063/1.5126216 Submitted: 31 August 2019 • Accepted: 6 October 2019 • Published Online: 4 November 2019 John M. Herberta) AFFILIATIONS Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, USA a)[email protected] ABSTRACT Since the introduction of the fragment molecular orbital method 20 years ago, fragment-based approaches have occupied a small but growing niche in quantum chemistry. These methods decompose a large molecular system into subsystems small enough to be amenable to electronic structure calculations, following which the subsystem information is reassembled in order to approximate an otherwise intractable supersys- tem calculation. Fragmentation sidesteps the steep rise (with respect to system size) in the cost of ab initio calculations, replacing it with a distributed cost across numerous computer processors. Such methods are attractive, in part, because they are easily parallelizable and there- fore readily amenable to exascale computing. As such, there has been hope that distributed computing might offer the proverbial “free lunch” in quantum chemistry, with the entrée being high-level calculations on very large systems. While fragment-based quantum chemistry can count many success stories, there also exists a seedy underbelly of rarely acknowledged problems. As these methods begin to mature, it is time to have a serious conversation about what they can and cannot be expected to accomplish in the near future. Both successes and challenges are highlighted in this Perspective. -
Anchoring the Potential Energy Surfaces of Homogenous and Heterogenous Dimers of Formaldehyde and Thiofomaldehyde
ANCHORING THE POTENTIAL ENERGY SURFACES OF HOMOGENOUS AND HETEROGENOUS DIMERS OF FORMALDEHYDE AND THIOFOMALDEHYDE by Christina Michelle Holy A thesis submitted to the faculty of The University of Mississippi in partial fulfillment of the requirements of the Sally McDonnell Barksdale Honors College Oxford May 2014 Approved by _____________________________________ Advisor: Professor Gregory Tschumper _____________________________________ Reader: Associate Professor Nathan Hammer _____________________________________ Reader: Professor Susan Pedigo © 2014 Christina Michelle Holy ALL RIGHTS RESERVED ii ACKNOWLEDGEMENTS Many people in the Department of Chemistry and Biochemistry here at the University of Mississippi were of great assistance during the work presented in this manuscript. I would like to thank the Mississippi Center for Supercomputing Research for the use of their computational facilities and the research group of Dr. Gregory Tschumper for their guidance and computational assistance. Specifically, I would like to thank Eric Van Dornshuld for his continual support and advisement throughout this research project. Lastly, I would like to thank my advisor, Dr. Gregory Tschumper, for allowing me to work in his laboratory as well as providing me with a worthwhile project to fulfill this thesis requirement. iii ABSTRACT This work characterizes five stationary points of the formaldehyde dimer, (CH2O)2, two of which are minima, seven newly-identified stationary points of the formaldehyde/thioformaldehyde (mixed) dimer, CH2O/CH2S, four of which are minima, and five newly-identified stationary points of the thioformaldehyde dimer, (CH2S)2 , three of which are minima. Full geometry optimizations and corresponding harmonic vibrational frequencies were performed on CH2O and CH2S as well as each of the dimer configurations (Figures 3-5). -
TA-02 Ion Science PID Response Factors USA V1.6.Pdf 1.43 MB
Technical/Application Article 02 Version 1.6 19 July 2016 WRH/FD Ion Science PID Response Factors PID Response Photoionization Detectors (PIDs) respond to a broad range of organic and a few inorganic gaseous and volatile chemicals (‘volatiles’). In order for PID to respond to a volatile, the photon energy of the lamp must be greater than its ionization energy. Ion Science PIDs are available with 10.0 eV, 10.6 eV, and 11.7 eV lamps. This Technical Article lists the response factors (‘RF’s’) for over 800 volatiles with PID engaging these lamps. The RF relates the sensitivity of PID to a volatile to the sensitivity to the standard calibration gas isobutylene. The higher the RF, the lower the sensitivity. In the table ‘ZR’ means there is no response, NA that the value has not been measured (Not Available), and NV means that the compound is not volatile enough to measure accurately. For chemicals not listed, contact Ion Science for more information. Isobutylene as Reference Gas It is always most accurate to calibrate a PID directly with the compound to be measured. However, standard gas cylinders of many chemicals are not readily available, and in such cases isobutylene is the standard reference gas used to calibrate. The response of these chemicals differs to isobutylene by the factors listed in the table below. This table allows measurement of all the listed volatiles using only isobutylene for calibration. To obtain the true concentration of the target volatile chemical, multiply the apparent reading by the response factor listed in the table: True Concentration = Apparent Response x Response Factor For example, anisole has a response factor (RF) of 0.47 with a 10.6 eV lamp. -
Few-Body Approach to Diffraction of Small Helium Clusters by Nanostructures
Few-body approach to diffraction of small helium clusters by nanostructures1 Gerhard C. Hegerfeldt2 Institut f¨ur Theoretische Physik, Universit¨at G¨ottingen Bunsenstr. 9, 37073 G¨ottingen, Germany and Thorsten K¨ohler3 Max-Planck-Institut f¨ur Str¨omungsforschung Bunsenstr. 10, D-37073 G¨ottingen, Germany Abstract We use few-body methods to investigate the diffraction of weakly bound systems by a transmission grating. For helium dimers, He2, we obtain explicit expressions for the transition amplitude in the elastic channel. 1 1. Introduction In recent years typical optics experiments have been carried over to atoms, among them diffraction by double slits [1] and by transmission gratings which were produced by nanostructure techniques [2, 3]. The usual wave-theoretical methods of classical optics (Huygens, Kirchhoff) seem to give excellent descriptions of these experiments [4] so that apparently not much more than a good textbook on classical optics seems to be needed. This simple picture, however, has changed. Recently Sch¨ollkopf and Toennies [2, 5, 6] have performed impressive diffraction experiments with helium dimers and helium clusters consisting of up to 26 atoms. A typical diffraction pattern arXiv:quant-ph/9809031v1 11 Sep 1998 is shown in Fig. 1. The helium dimer He2, discovered a few years ago [8, 2], has an extremely low binding energy of −0.11 µeV [7], with no excited states. The binding energy is much smaller than the incident kinetic energy of typical experiments. Its diameter is estimated to be about 6 nm [9]. Present day slit widths are as low as 50 nm and a further reduction is expected. -
Criegee Intermediate-Hydrogen Sulfide Chemistry at the Air/Water
Chemical Science View Article Online EDGE ARTICLE View Journal | View Issue Criegee intermediate-hydrogen sulfide chemistry at the air/water interface† Cite this: Chem. Sci.,2017,8,5385 Manoj Kumar,‡a Jie Zhong,‡a Joseph S. Francisco*a and Xiao C. Zeng*ab We carry out Born–Oppenheimer molecular dynamic simulations to show that the reaction between the smallest Criegee intermediate, CH2OO, and hydrogen sulfide (H2S) at the air/water interface can be observed within few picoseconds. The reaction follows both concerted and stepwise mechanisms with former being the dominant reaction pathway. The concerted reaction proceeds with or without the Received 22nd April 2017 involvement of one or two nearby water molecules. An important implication of the simulation results is Accepted 9th May 2017 that the Criegee-H2S reaction can provide a novel non-photochemical pathway for the formation of DOI: 10.1039/c7sc01797a aC–S linkage in clouds and could be a new oxidation pathway for H2S in terrestrial, geothermal and rsc.li/chemical-science volcanic regions. Creative Commons Attribution 3.0 Unported Licence. Carbon–sulfur linkages are ubiquitous in atmospheric, combus- hydrogen sulde (H2S) under water or acid catalysis could account tion, and biological chemistries. Thioaldehydes comprise an for the atmospheric formation of thioaldehydes and provide useful important class of carbon–sulfur compounds that has a broad guidelines for efficiently synthesizing thioaldehydes within labo- chemical appeal. For example, thioformaldehyde (HCHS) has been ratory environment.7,9