The crystal structure of imidazole at 103 K by neutron diffraction

McMullan, R. K.; Epstein, Joel; Ruble, J. R.; Craven, B. M.

doi:10.1107/s0567740879004441

Cited by 113 publications

(76 citation statements)

References 3 publications

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“…592 (4) 402 (6) idealized picture of imidazole, A, and to what is H35 624(4) 267 (7) HO 1009 (4) 133 (6) found in imidazole (McMullen et al, 1979;Martinez-Carrera, 1966 We have no reasonable explanation for these observations. Structure B might be stabilized by hydrogen bonding in tings 1 and 2, but the effect is also observed in ring 3 where no hydrogen bonding is present.…”

Section: Tris(2-imidazolyl)phosphine Hemihydratementioning

confidence: 40%

Tris(2-imidazolyl)phosphine hemihydrate

Copping¹,

Frampton²,

Howard-Lock³

et al. 1992

Acta Crystallogr C

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Section: Tris(2-imidazolyl)phosphine Hemihydratementioning

confidence: 40%

Tris(2-imidazolyl)phosphine hemihydrate

Copping¹,

Frampton²,

Howard-Lock³

et al. 1992

Acta Crystallogr C

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“…Within the limits of precision, the dimensions of the coordinated imidazole rings in the present complex are the same as in free imidazole as determined by neutron diffraction (Craven, McMullan, Bell & Freeman, 1977;McMullan, Epstein, Ruble & Craven, 1979). Manganese-imidazole complexes in which the Mn n atoms have coordination numbers 6, 5 and 4, respectively, are listed in Table 3.…”

Section: Bond Lengths (~) and Angles (O) With Esd 'S In Parenthesesmentioning

confidence: 92%

trans-Diaquatetrakis(imidazole)manganese(II) dichloride, [Mn(C3H4N2)4(H2O)2]Cl2

Garrett¹,

Guss²,

Freeman³

1983

Acta Crystallogr C

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“…The smaller X-ray values for U U may be due to the crystal temperature being somewhat lower than the measured value. These X-ray intensity data were collected before we adopted the practice of measuring the changes in crystal lattice parameters over a range of temperature so as to match the temperatures of the X-ray and neutron data collection (McMullan, Epstein, Ruble & Craven, 1979). However, this may not be a satisfactory explanation.…”

Section: The Charge-density Refinementsmentioning

confidence: 99%

The charge density in polymorph II of 5,5-diethylbarbituric acid (barbital) at 198 K

Craven¹,

Fox²,

Weber³

1982

Acta Crystallogr Sect B

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The charge density in barbital II (CaH12N203) at 198K has been determined from 3220 X-ray reflections (Mo Ka radiation) having sin 0/2 < 1.08 A -I and I Fobsl > 3o. Atomic positional parameters and H-atom thermal parameters were given fixed values determined in a previous neutron structure determination. Other parameters, including electron population parameters, and third-order temperature factors, were obtained by least-squares refinement, assuming Stewart's rigid pseudoatom formalism. Results show that in chains of four C atoms there appears to be an alternation of atomic charges which may represent an inductive effect. The H atom which is H-bonded is significantly depleted of electronic charge (~0.2 e) compared with methyl or methylene H atoms. There is a polarization of charge density in C-N and C-O bonds. Carbonyl O atoms have paired lobes of excess electron density (~l.2eA -3) above and below the amide plane. It has not been explained why these lobes are found in various orientations in amide crystal structures. The calculated molecular dipole moment is 0.7 (1.2) debye (1 debye = 3.336 x 10 -30 C m) with negative charge displacement towards atom C(5) and positive towards 0(2).

show abstract

The crystal structure of imidazole at 103 K by neutron diffraction

Cited by 113 publications

References 3 publications

Tris(2-imidazolyl)phosphine hemihydrate

Tris(2-imidazolyl)phosphine hemihydrate

trans-Diaquatetrakis(imidazole)manganese(II) dichloride, [Mn(C3H4N2)4(H2O)2]Cl2

The charge density in polymorph II of 5,5-diethylbarbituric acid (barbital) at 198 K

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