Microwave Spectra and Structures of Isothiazole, 1,2,4-Oxadiazole and Imidazole

Griffiths, John H.; Wardley, A.; Williams, Valerie E.; Owen, Noel L.; Sheridan, J.

doi:10.1038/2161301a0

Cited by 40 publications

(11 citation statements)

References 9 publications

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“…16 Since basis set effects are small, the discrepancies between our best calculations (MP2/C) and experiment for µ and θ must largely be due to the effects of molecular vibration and higher order electron correlation. 16 Since basis set effects are small, the discrepancies between our best calculations (MP2/C) and experiment for µ and θ must largely be due to the effects of molecular vibration and higher order electron correlation.…”

Section: Dipole Momentsmentioning

confidence: 82%

Polarizabilities of Oxazoles: Ab Initio Calculations and Simple Models

1996

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Ab initio, electron correlated calculations of the equilibrium geometries, dipole moments, and static dipole polarizabilities are reported for 10 heteroaromatic five-membered rings: furan, oxazole, isoxazole, all four oxadiazoles, both oxatriazoles, and oxatetrazole. Our geometries and dipole moments agree well with available experimental microwave determinations. The polarizabilities are expected to be accurate to within 5%. Structural isomerism affects the dipole moments strongly but the dipole polarizabilities are rather insensitive to it. Uncoupled Hartree-Fock calculations indicate that as much as half the polarizability comes from the σ-electrons. Simple empirical formulas based upon atom-and bond-additive models correlate the calculated polarizabilities of 20 five-membered heteroaromatic rings (10 azoles and 10 oxazoles) quite well. * Fax 506-453-4981; e-mail: ajit@unb.ca. X Abstract published in AdVance ACS Abstracts, April 15, 1996.Figure 1. Oxazoles with MP2/C dipole moments shown to scale, with the arrowhead pointing to the negative end.

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Section: Dipole Momentsmentioning

confidence: 82%

Polarizabilities of Oxazoles: Ab Initio Calculations and Simple Models

1996

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“…57 Table 1 shows the molecular dipole moment at each level of theory, and compares it to experiment. An experimental value of 3.8 AE 0.4 D, determined by Stark measurements, was reported 58 in 1967. A more recent experimental value of 3.66 AE 0.06 D was published 59 in 1982 and mentioned in a review 60 on molecular electric moments.…”

Section: Introductionmentioning

confidence: 96%

Simulation of liquid imidazole using a high-rank quantum topological electrostatic potential

Shaik

Liem

Yuan

et al. 2010

Phys. Chem. Chem. Phys.

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Rigid body molecular dynamics simulations were carried out on pure liquid imidazole at four different temperatures and at 1 atm. Imidazole, which is important both in life science and materials science, is one of the simplest molecules to possess both a lone pair and a π system. These two features are known to benefit from multipolar electrostatics. Here the electrostatic interaction is governed by atomic multipole moments obtained from topologically partitioned ab initio electron densities. The non-electrostatic terms are modeled with Lennard-Jones parameters adjusted to fit the experimental liquid density. All σ values are incrementally increased by one single scaling factor. We report on how the presence of multipolar electrostatics influences the local structure, dynamics and thermodynamics of the liquid compared to electrostatics by atomic point charges. The point charge force field exaggerates the number of π-stacked dimers in the liquid, and underestimates the number of hydrogen-bonded dimers. The effect of the temperature on the local structure of liquid imidazole was analysed using radial and spatial distribution functions.

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“…Building on this, and their previous study in Ref. [18], Christen et al provided a set of rotational constants for the molecule's parent species, as well as the D, 13 C, and 15 N isotopologues determined from data up to 40 GHz [19]. This allowed a comprehensive structure of imidazole in the gas phase to be constructed, which is re-evaluated here based on our extended data set.…”

Section: Introductionmentioning

confidence: 97%