Study of the ν1, ν1 + ν3 and ν2 + ν3 infrared bands of ONCl

A type (ΔK_a = 0) rovibrational lines of the near-prolate asymmetric top ¹⁶O¹⁴N³⁵Cl have been assigned on high resolution Fourier transform spectra: 820 lines of the ν₁ band, centered around 1800 cm⁻¹, 435 lines of the ν₁ + ν₃ band, centered around 2131 cm⁻¹, and 257 lines of the ν₂ + ν₃ band, centered around 925 cm⁻¹. Least-squares calculations have been carried out over these lines, using the A reduced Watson's hamiltonian in I^r representation; r.m.s. standard deviations of 0.0016 cm⁻¹, 0.0016 cm⁻¹ and 0.006 cm⁻¹ have been respectively obtained, making it possible to measure molecular constants of the (001), (101) and (011) vibrational levels of ¹⁶O¹⁴N³⁵Cl.     

The analysis of high-resolution spectra of the ν2 and ν5 bands of CH335Cl and CH337Cl

The ν₂ and ν₅ bands of CH³₃⁵Cl and CH³₃⁷Cl between 1300 and 1600 cm⁻¹ have been analysed using a Fourier transform spectrum with 0.006 cm⁻¹ resolution. For CH³₃⁵Cl, the microwave data and 1200 lines from the IR spectrum with J⩽ 50 were fitted with an overall r.m.s. error of 0.00079 cm⁻¹ using the method of predicative observations. A similar fit for 900 lines of CH³₃⁷Cl gave an overall r.m.s. error of 0.00055 cm⁻¹, providing erroneous microwave data on the ν₅ level are omitted. Improved molecular constants are reported for both isotopic species. As expected, the values for ν₂ and ν₅ are little affected by chlorine isotopic substitution.     

FTIR spectra of the 2ν4, ν4 + ν6 and 2ν6 bands of formaldehyde

High resolution IR spectra of the overtones and the combination band of the ν₄ and ν₆ modes of formaldehyde (2ν₄, ν₄ + ν₆ and 2ν₆) were measured in the region of 2200–2650 cm⁻¹ using FTIR. The combination band ν₄ + ν₆, whose dipole transition is forbidden from molecular symmetry, was observed due to the intensity borrowed from the other bands. The observed frequencies were analysed by a Hamiltonian in which A-type Coriolis interactions and Darling—Dennison interaction were taken into account. The ratio and the relative signs of the transition dipole moments of the overtone bands, μ_2ν4 and μ_2ν6, have been determined by analysing the intensity distribution of the vibration—rotation lines.     

High-resolution FTIR study of the 3ν1, rovibrational band of 16O14N35Cl

818 A type (ΔK_a = 0) rovibrational lines of the near-prolate asymmetric top ¹⁶O¹⁴N³⁵Cl have been assigned in the 3v₁     

Vibration—rotation spectrum of methyl cyanide— analyses of ν2 and ν3 + ν4 bands

Infrared spectrum of methyl cyanide was recorded in the region from 2235–2320 cm⁻¹ with a working resolution of 0.05 cm⁻¹. The transitions of two parallel type bands ν₂ and ν₃ + ν₄ as well as the associated hot bands are assigned. Since the molecular constants for the ground and ν₈ vibrational states are known precisely by microwave study for this molecule, highly accurate molecular constants for the upper vibrational states have been determined from those data by a least-squares procedure.     

Study of the spectrum of CH379Br between 1520 and 1700 cm−1: The ν3 + ν6 and the ν5 rovibrational bands

The ν₃ + ν₆ band of CH₃ ⁷⁹Br has been directly analyzed for the first time, and an r.m.s. standard deviation of 0.0035 cm⁻¹ was obtained over 394 lines of K″ΔK = 2 up to 12, through a least-squares calculation using an unperturbed model. Nevertheless discrepancies occur on sub-bands with K″ ⩾ 9, which remain not yet understood. In particular it seems difficult to explain them by a Fermi resonance with the ν₅ band, since it has been possible to fit properly around 580 lines of this band, belonging to sub-bands K″ΔK = 7 up to 16, taking only into account the Coriolis resonance with the ν₂ band and the l(2,2) resonance of ν₅.     

Vibrational spectra and force constants of symmetric tops—XLII. Rovibrational spectra of CF3I in the ν2, ν3, 2ν3 and ν2 + ν3 regions

The gas phase i.r. spectrum of CF₃I has been investigated in the ν₂, ν₃, 2ν₃ and ν₂ + ν₃ region with a resolution of 0.04 cm⁻¹. Rotational J clusters have been resolved, and several vibrational and rovibrational parameters of ν₂, 743.364(8) cm⁻¹ and ν₃, 286.303(3) cm⁻¹, have been determined by polynomial methods and by band contour simulation.     

ℓ-Resonance effects in the νv5, 2ν5←ν5, and ν4 + ν5←ν4 bands of C2H2 and 13C12CH2 near 13.7 μm

An extension to the previous LSCD (lower state combination difference) determination of molecular parameters involving acetylene's ν₅ fundamental and the strongest one quantum hotbands, 2ν₅←ν₅ and ν₄ + ν₅←ν₄ [J. Molec. Spectrosc. 146, 389 (1991)] has been made. A novel iterative numerical diagonalization procedure was employed to fit the vibrational states involved in the seven one quantum hotbands. This method utilizes the Hellmann—Feynman theorem to calculate first derivatives and singular value decomposition (SVD) in its least-square procedure and permits the simultaneous evaluation of the effective dipole moment responsible for the ℓ-type resonance effect upon IR intensities. A set of molecular parameters describing the rotation—vibration levels of the ground state, ν₅, ν₄, 2ν₅ and ν₄ + ν₅ for the major isotope and for ¹³C¹²CH₂ are reported based upon FT-spectrometric data taken at the McMath Solar Telescope Observatory. The improved spectroscopic parameters retrieved from this investigation will serve as a database for modelling abundances of acetylene in various astrophysical sources.     

Raman spectrum of carbonates MIICO3 in the 1100-1000cm −1 region: observation of the ν1, mode of the isotopic (C16O182O)2− ion

The Raman spectrum of a series of carbonates M^IICO₃ with aragonite or calcite structure has been reinvestigated in the 1100-1000 cm⁻¹ region, corresponding to the totally symmetric stretch (ν₁) of the (CO₃)²⁻ anion. Besides the very strong peak corresponding to the ν₁ mode of the (C¹⁶O₃)²⁻ ion, nearly all spectra exhibit a very weak satellite peak whose frequency agrees well with the calculated ν₁ frequency of the isotopic ion (C¹⁶O¹⁸₂O)⁻². Small deviations from the theoretical values are qualitatively discussed on the basis of vibrational couplings between near-neighbour anions.     

Chlorination of charged buckyballs: reactions of C60x+ cations (x = 1–3) with Cl2, CCl4, CDCl3, CH2Cl2, and CH3Cl

The chlorination of singly and multiply charged C₆₀ cations has been investigated with the selected-ion flow tube technique. Observations are reported for the reactions of C₆₀^·+, C₆₀²⁺ and C₆₀^·3+ with Cl₂, CCl₄, CDCl₃, CH₂Cl₂ and CH₃Cl at room temperature (295 ± 2 K) in helium at a total pressure of 0.35 ± 0.02 Torr. C₆₀^·+ and C₆₀²⁺ were observed not to chlorinate, or react in any other way, with these five molecules. Chlorine also did not react with C₆₀^·3+, but bimolecular chloride transfer and electron transfer reactions, reactions that result in charge reduction/charge separation, were observed to occur with CCl₄, CDCl₃, CH₂Cl₂ and CH₃Cl. Chloride transfer was the predominant channel seen with CCl₄, CDCl₃ and CH₂Cl₂ while electron transfer dominates the reaction with CH₃Cl. These results are consistent with trends in chloride affinity and ionization energy. The reluctant chlorination of the first two charge states of C₆₀ is attributed to the energy required to distort the carbon cage upon bond formation, while the observed chloride transfer to C₆₀^·3+ is attributed to the greater electrostatic interactions with this ion.     

Conductometric study of complexation reaction of 4′-nitrobenzo-15-crown-5 with Mn+2, Co+2, Y+3, and ZrO+2 cations in acetonitrile,methanol and their binary solvent solutions

The complexation reactions of Mn²⁺, Co²⁺, Y³⁺, and ZrO²⁺ cations with the macrocyclic ligand, 4′-nitrobenz-15-crown-5 (4′-NB15C5), in acetonitrile (AN), methanol and AN-MeOH binary mixtures have been studied at various temperatures using the conductometric method. The conductance data stand for the Me : L stoichiometric ratio 1 : 1. Values of the formation constants of the complexes were accumulated by plotting molar conductivity curves using the computer program, GENPLOT. The order of stability of the metal-ion complexes in pure AN at 15°C was found to be: (4′-NB15C5 · ZrO)²⁺ > (4′-NB15C5 · Mn)²⁺ ≈ (4′-NB15C5 · Co)²⁺ > (4′-NB15C5 · Y)³⁺. In the case of AN-MeOH binary solvent solutions with 50 and 75 mole percent of AN at the same temperature, the sequence of stability of the complexes was the following: (4′-NB15C5 · Mn)²⁺ > (4′-NB15C5 · ZrO)²⁺ ≈ (4′-NB15C5 · Co)²⁺ 〉 (4′-NB15C5 · Y)³⁺, and (4′-NB15C5 · Mn)²⁺ > (4′-NB15C5 · Y)³⁺ ≈ (4′-NB15C5 · Co)²⁺ > (4′-NB15C5 · ZrO)²⁺, respectively. The complexes formed are entropy stabilized in all cases.     

Rovibrational state specific scattering distributions of the O((1)D) + CD(4)→ OD + CD3 (v1, v2, N) reaction

The rovibrational state distributions and state-resolved scattering distributions of CD(3) radicals produced by the reaction O((1)D) + CD(4) were investigated by crossed molecular beam ion imaging. The rotational structure of the resonance-enhanced multiphoton ionization spectrum of CD(3) in the ground vibrational state indicates that the low K rotational states of CD(3) radicals are preferentially populated. The state-resolved scattering distributions of CD(3) (v = 0) and those of the excited states of the out-of-plane bending (v(2)) mode exhibit a structureless forward-scattering component due to an insertion pathway and a structured backward-scattering component due to an abstraction path. The scattering distributions of CD(3) in the excited state of the C-D symmetric stretch (v(1)) do not exhibit the abstraction component. The scattering distribution of the abstraction component gradually extends in the forward direction with increasing intensity as the v(2) vibration becomes more strongly excited. This suggests that abstraction with a larger impact parameter results in stronger excitation of v(2).     

Quantum-mechanical calculation of the reactions D + FH(ν = 0, 1, 2) → DF(ν′) + H and H + FD(ν = 0, 1, 2, 3) → HF(ν′) + D on a realistic potential energy surface

Collinear (two-mathematical-dimensional (2MD)) coupled-channel quantum-mechanical calculations have been performed on the reactions D + FH(ν = 0, 1, 2) → DF(ν′) + H and H + FD(ν = 0, 1, 2, 3) → HF(ν′) + D on a potential energy surface with a 40 kcal/mole barrier to exchange. This barrier height is close to that predicted by ab initio calculations and suggested by experiments. The relative effectiveness of reagent vibrational and translational excitation to promote reaction is considered. A one-mathematical-dimensional (1MD) model for these reactions is constructed and is shown to work very well for the D + FH reaction at high temperatures, and less well for that reaction at lower temperatures as well as for the reverse H + FD reaction. Possible reasons for the breakdowns of this model are discussed.     

Crystal Structure of 3, 7-Dihydroxy1-1, 5-diazacyclooctane Dihydrobromide C_6H_(14)N_2O_2. 2HBr. EtOH

1I7NTRODUCT1ONAsequenceofnovelhydroxylmesocyclicdiaminesLl-3Jweresynthesizedinourlaboratoryandemployedtobindtransitionmetalions.Wehavepreviouslyreported[']thatoneofthesemesocycles,3-hydroxyL1,5-diazacycloheptane,adoptstranschair-chairconformationinthecomplexes,whereasitlookslikeacrownintheabsenceofguests.Here,wereportthemolecularstructureofthetitlemesocyclicdiaminewhichbearsdoublehydroxylgroups.2EXPERIMENTALThetitlecompound['Jwasheatedtobedissolvedinalittlewater,followedbyad-ditiono…     

NMR study (1H, 13C and 31P) of the {(C2H5)2N}nPX3−n compounds (X = Cl,C2H5; n = 0, 1, 2, 3)

¹H, ¹³C and ³¹P NMR data of the compounds {(C₂H₅)₂N}_nPX_3−n, (X = Cl, C₂H₅; n = 0, 1, 2, 3) are reported. While the ¹H and ¹³C resonances from the PEt moiety rather follow the electron-withdrawing effect of the NEt₂ substituent, ¹H and ¹³C chemical shift data from the NEt₂ moiety reveal a quite important shift contribution originating from sterically induced polarization of the CH bonds . ³¹P chemical shift data are interpreted in terms of inductive effects but the anomalous diamagnetic shift deviation from linearity for X = Cl suggests a minor contribution from

multiple bonding. The general trend observed in the ³¹P-couplings is quite straightforward and can be qualitatively explained by Bent's rule.     

Synthesis of (±)-2-Methoxy-9a-Carbamorphinan and (±)-2-Methoxy-9a-Carba-14α-Morphinan: Acid Catalyzed Cyclizations of 1-m-Methoxybenzyl-4, 4a,5,6,7,8-Hexahydronaphthalen-2(3H)-ONE and 1 -m-Methox Ybenzyloctalins

The bridged-ethers, (±)-2-methoxy-9a-carbamorphinan (1b) and (±)-2-methoxy-9a-carba-14α-morphinan(2b) have been synthesized. The acid-catalyzed cyclizations of 1-m-methoxy benzyloctalone 3b and 1-m-methoxybenzyloctalins 4b proceed with high regio-and stereoselectivities leading mostly to the bridged-ketone 14 and ether 1b respectively, along with o-methoxy-tetracyclic ketone 15 and the ether 17, in addition to other minor products.     

Effect of non-aqueous solvents on stoichiometry and selectivity of complexes formed between 4′-nitrobenzo-15-crown-5 with Fe3+, Y3+, Cd2+, Sn4+, Ce3+ and Au3+ metal cations

The complexation processes between Fe³⁺, Y³⁺, Cd²⁺, Sn⁴⁺, Ce³⁺ and Au³⁺ metal cations with macrocyclic ligand, 4′-nitrobenzo-15-crown-5 (4′NB15C5), were studied in acetonitrile (AN), methanol (MeOH) and nitromethane (NM) solvents at different temperatures using conductometric method. The conductance data show that the stoichiometry of the complexes formed between this macrocyclic ligand and Cd²⁺, Au³⁺ cations is 1: 1 (ML), but in the case of Fe³⁺, Y³⁺ and Ce³⁺ metal cations, 2: 1 (M₂: L) and 2: 2 [M₂: L₂] complexes are formed in nitromethane solutions. The results show, that the selectivity of 4’NB15C5 for the studied metal cations in methanol solutions at 15°C is: Sn⁴⁺ > Cd²⁺ > Y³⁺ > Fe³⁺ ∼ Ce³⁺ > Au³⁺, but in the case of acetonitrile, the stability order was found to be: Y³⁺ > Au³⁺ > Fe³⁺ > Cd²⁺. The values of stability constants of the 1: 1 [M: L] complexes were determined from conductometric data using a GENPLOT computer program. The values of thermodynamic parameter (ΔH _c ^o and ΔH _c ^o) for formation of the complexes were obtained from temperature dependence of the stability constants, using the van’t Hoff plots. The results show that the values of standard enthalpy (ΔH _c ^o) and standard entropy (ΔH _c ^o) change with the nature of the non aqueous solvents.