1070-74-2Relevant academic research and scientific papers
Reactions of C3H3+ with Acetylene and Diacetylene in the Gas Phase
Ozturk, F.,Baykut, G.,Moini, M.,Eyler, J. R.
, p. 4360 - 4364 (1987)
The reactions of linear C3H3+ with acetylene, diacetylene, and deuteriated acetylene were investigated with a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer.A rate coefficient of (1.4 +/- 0.7)E-9 cm3/s was obtained for the reaction of linear C3H3+ with diacetylene while no production of larger ions was observed with acetylene.The ejection capabilities of FTICR were used to study the reactions of different C3H3+ precursors with C2H2 in order to investigate the possible production of C5H5+ from ionic sources other than C3H3+ present in the reaction medium.Linear C3H3+ isomerized to the cyclic form in the reactions with both acetylene and diacetylene.The isomerization was shown to take place via a long-lived C5H5+ complex by isotope exchange reactions between linear C3H3+ and deuteriated acetylene.Results are discussed in relation to previous work involving C3H3+ reactions and a proposed ionic route to soot formation.
Comparison of bending, C-C stretching, and collision energy effects on the reaction of C2H2+ with D2
Chiu, Yu-hui,Yang, Baorui,Fu, Hungshin,Anderson, Scott L.,Schweizer, Martin,Gerlich, Dieter
, p. 5781 - 5788 (1992)
We report the effects of vibrational excitation and collision energy on the cross sections and branching ratios for reaction of acetylene cations with D2, using two different guided-ion-beam instruments.Two major reaction channels are observed, both of which are nearly thermoneutral.Hydrogen atom exchange is slightly exoergic due to zero point energy, and is inhibited by both collision and vibrational energy.Formation of the two isotopic C2H3+ products is enhanced by collision energy and C-C stretching vibration, but not by bending vibration.The branching ratios at low collision energies are consistent with reaction via an intermediate complex, and Rice-Ramsberger-Kassel-Marcus (RRKM) analysis is used to extract further information.At collision energies above 1 eV, D-atom transfer by a direct mechanism is also observed as a route to C2H2D+ production.Comparison of our results using both the Stony Brook and Freiburg instruments is made with the state-selected experiments of Honma, Kato, Tanaka, and Koyano , who previously studied both the C2H2+ + D2 and C2D2+ + H2 isotopic reactants.Our results for C2H2+ + D2 are consistent with their C2D2+ + H2 data for all collision energies and with their C2H2+ + D2 data at 0.2 eV collision energy.We do not reproduce the anomalous vibrational effects they reported for 1 and 2 eV collision energies.
Mechanistic studies on platinum(II) catalyzed hydroarylation of alkynes
Hahn, Christine,Miranda, Mayra,Chittineni, Nagendra P. B.,Pinion, Trent A.,Perez, Ricardo
, p. 3040 - 3050 (2014)
The dicationic acetylene platinum(II) complex [Pt(PNP)(C2H 2)](BF4)2 (PNP = 2,6- bis(diphenylphosphinomethyl)pyridine) was generated in situ by ligand substitution from the ethylene complex [Pt(PNP)(C2/sub
Contrasting Free Energies of Electron Transfer from - and Annulenes to Their Perdeuteriated and Per-(13)C Analogues
Stevenson, Gerald R.,Peters, Steven J.,Reidy, Kerry A.,Reiter, Richard C.
, p. 1877 - 1882 (1992)
A very large equilibrium isotope effect (confirmed via physical, separation oof the isotopes involved) was observed via the EPR analysis of a mixture of benzene and perdeuteriated-per-(13)C-benzene competing for a deficient number of electrons in tetrahyydrofuran (THF) in the presence of 18-crown-6 (18C6).The Keq for the reaction C6H6.-, K+(18C6) + (13)C6D6 = C6H6 + (13)C6D6.-, K+(18C6) is 0.096 +/- 0.008 at 100 deg C.An analogous competition for electrons exists between annulene and perdeuteriated-per-(13)C-annulene.In contrast to the benzene system the Keq for the reaction C8H8.-, Na+ + (13)C8D8 = C8H8 + (13)C8D8.-,Na+ in liquid ammonia is 1.20 +/- 0.04 at -100 deg C.Similar contrasting results (but smaller in magnitude) were observed for the benzene and cyclooctatetraene perdeuteriated and per -(13)C systems.The results are interpreted in terms of the divergence of the annulene system from aromatic character upon electron addition and the convergence of the annulene system toward aromatic character upon electron addition.
MICROWAVE ROTATIONAL SPECTRUM AND PROPERTIES OF HYDROGEN-BONDED DIMER FORMED BY TRIMETHYLAMINE AND ACETYLENE
Legon, A. C.,Rego, C. A.
, p. 137 - 152 (1988)
The rotational spectra of the four isotopic species (CH3)3-14N...HCCH, (CH3)3-14N...DCCH, (CH3)3-14N...HCCD and (CH3)3-14N...DCCD of a hydrogen-bonded dimer formed between trimethylamine and acetylene have been observed by pulsed-nozzle, Fourier-transform microwave spectroscopy.The ground-state spectroscopic constants determined for these symmetric-top molecules are: For (CH3)3-14N...HCCH it has been established that the 14N-nuclear quadrupole coupling constant varies linearly with K2 according to χ(K) = χ(K = 0) + (6.6*10-3)K2 MHz.The following molecular properties have been determined for the dimer from the spectroscopic constants: r(N...C) = 3.254(4) Angstroem, θav = 15.43(9) deg and k? = 5.82(2) N m-1.
Rotational spectroscopy of mixtures of ethyne and iodine monochloride: Isolation and characterisation of the π-type complex C2H2···ICl
Davey,Legon
, p. 3721 - 3726 (1999)
The ground-state rotational spectrum of a complex formed by ethyne and iodine monochloride was observed by using pulsed-nozzle, Fourier-transform microwave spectroscopy. A fast-mixing nozzle was utilised to avoid chemical reaction of the component gases prior to their supersonic expansion. Rotational constants A0, B0 and C0, quartic centrifugal distortion constants Δ(J), Δ(JK) and δ(J), and halogen nuclear quadrupole coupling constants χ(aa)(X) and {χ(bb)(X) χ(cc)(X)}, where X = Cl or I, were determined for the three isotopomers C2H2···I35Cl, C2H2···I37Cl and C2D2···I35Cl. Detailed interpretation of the rotational constants established that the equilibrium geometry of the complex has a planar, T- shape of C(2v) symmetry in which ethyne acts as the bar of the T. This geometry, with the zero-point distance r(*···I) = 3.115(1) A between the centre of the π-bond of ethyne and the nearest halogen atom I, establishes that the interaction in this complex is between ethyne as a π electron donor and I of ICl as the electron acceptor. The halogen nuclear quadrupole coupling constants χ(aa)(X) were interpreted on the basis of a simple model to show that, on complex formation, fractions δ1 = 0.026 and δ2 = 0.056 of an electronic charge are transferred from the ethyne π bond to I and from I to C1, respectively, leading to a net decrease of 0.030e at I. The complex is weakly bound, according to the intermolecular stretching force constant kσ = 12.2(1) Nm-1 determined for the isotopomers C2H2···I35Cl and C2H2···I37Cl from Δ(J) values. The opportunity is taken to compare the properties of C2H2···ICl established here with those similarly determined for the series C2H2···XY, where XY = Cl2, ClF, or BrCl.
The phenylcyclooctatetraene anion radical and dianion: An intramolecular charge and spin distribution isotope effect
Stevenson, Gerald R.,Burton, Richard D.,Reiter, Richard C.
, p. 399 - 403 (1992)
EPR studies on the anion radicals and 13C NMR studies of the dianions of phenylcyclooctatetraene ([6]-[8]), phenylcyclooctatetraene-d7, and phenyl-d5-cyclooctatetraene show that deuteriation of the cyclooctatetraenyl moiety perturbs and phenyl group spin and charge distributions in the anion radical and dianion, respectively. However, deuteriation of the phenyl moiety does not alter these distributions in the cyclooctatetraenyl moiety. The upfield shift in the chemical shifts of the phenyl carbons in the dianion and the increased spin density in the phenyl moiety in the anion radical, resulting from deuteriation of the eight-membered ring, is explained in terms of the different degrees of twist between the COT and phenyl rings. Since there is more zero-point energy in the coplanar arrangement and the force constant for C-D or C-H stretching mode should be maximized in a coplanar arrangement, [6]-[8]*- will tend to be more twisted than will [6]-[8]-d7*-. The deuteriation studies have further shown that the nature of the spin distribution in the anion radical of [6]-[8] has long been fundamentally misunderstood.
Deuterium Nuclear Magnetic Resonance spectroscopy. 1 - Larmor Frequency Ratio, Referencing and Chemical Shift
Al-Rawi, Jasim M. A.,Behnam, George Q.,Taha, Nihad I.
, p. 198 - 201 (1981)
Precise values for the ratio of the Larmor frequencies, w1H/w2H, were measured at constant field for various organic compounds.The values of the Larmor frequency ratio depend on carbon-hydrogen bond hybridization.The best ratio for the ghost referencing of 2H NMR spectra was then determined (6.514399862).This value enables an accurate ghost reference for any 2H NMR spectrum to be derived from the observed 1H NMR frequency of the normal internal reference.Deuterium and proton chemical shifts measured from internal, partially deuteriated TMS under the same conditions are shown to be the same.
INTERNAL ROTATION AND FRAMEWORK RELAXATION IN ETHENE THIOL
Almond,V.,Permanand, R. R.,Macdonald, J. N.
, p. 337 - 352 (1985)
New and existing data on the ground and excited CS torsional states of the stable rotamers of ethene thiol have been analysed to give a potential function for internal rotation around the CS bond.The barrier between the syn and anti rotamers is found to be 800 cm-1 and that at the planar anti conformation itself to be 12 cm-1.The syn conformation is 50 cm-1 more stable than the 'quasi-planar' anti conformation.Satisfactory reproduction of the observed trends in rotational constants with torsional excitation has been achieved by introducing extensive relaxation of the CCS angle and the CS bond length during internal rotation.The CCS angle reduces by up to 5 deg whilst the CS bond length increases by up to 0.02 Angstroem during rotation from the syn to anti conformation.The use of ab initio M.O. calculations to provide an indication of the most significant aspects of structure relaxation is described.
Thermal rearrangement of 2,5-bis(dicyanomethylene)bicyclo[4.2.0]oct-7-ene and 2,5-bis(dicyanomethylene)bicyclo[4.2.0]octa-3,7-diene. Unexpected formation of 2,6-bis(dicyanomethylene)bicyclo[3.3.0]octa-1(5)-ene and -octa-3,7-diene, new electron acceptors
Kawase, Takeshi,Okada, Tomoaki,Enomoto, Tetsuya,Kikuchi, Takayuki,Miyake, Yoji,Oda, Masaji
, p. 1793 - 1799 (2003)
Upon heating at 200 °C in o-dichlorobenzene, 2,5-bis(dicyanomethylene)bicyclo[4.2.0]octa-3,7-diene gave rise to 2,6-bis(dicyanomethylene)bicyclo[3.3.0]octa-3,7-diene by a rearrangement as a sole isolable product in modest yield, and no trace of 5,8-bis(dicyanomethylene)cycloocta-1,3,6-triene, the expected product, was detected. On the other hand, 2,5-bis(dicyanomethylene)bicyclo[4.2.0]octa-7-ene underwent a thermal reaction at lower temperature (110 °C in toluene) to give 5,8-bis(dicyanomethylene)-1,3-cyclooctadiene, the normal ring-opened product, and 2,6-bis(dicyanomethylene)bicyclo[3.3.0]octa-1(5)-ene, a rearranged product, in about 1:1 ratio. The rearranged product has a planar 1,1,6,6-tetracyanohexatriene structure (X-ray analysis), and shows a considerably lower electron affinity than that of tetracyano-ethylene and 7,7,8,8-tetracyano-p-quinodimethane. The electron acceptor also formed a crystalline 1:1 charge transfer complex with tetrathiafulvalene, of which electronic conductivity was near insulating (1.1 × 10-7 S cm-1). We have proposed a possible mechanism for the rearangements involving the zwitterionic intermediates.
