Acta Crystallographica Section B

Structural Science

Volume 54, Part 1 (February 1998)

Cover illustration: Space filling representation of the hydrated anionic framework formed by trimesic acid around piles of cobalticinium cations in crystalline [(C₅H₅)₂Co][(H₃TMA)(H₂TMA)].2H₂O. Graphics (picture or drawing) obtained using SCHAKAL by E. Keller, University of Freiburg, Germany. Courtesy of D. Braga and F. Grepioni

international union of crystallography
research papers
short communications

international union of crystallography

Acta Cryst. (1998). B54, 1-7 [doi:10.1107/S0108768198099911]

Notes for Authors

research papers

Acta Cryst. (1998). B54, 8-17 [doi:10.1107/S0108768197008963]

X-ray and Electron Diffraction Study of MgO

V. G. Tsirelson, A. S. Avilov, Yu. A. Abramov, E. L. Belokoneva, R. Kitaneh and D. Feil

Synopsis: Precise X-ray and electron diffraction studies of MgO have been performed. Experimental structure amplitudes have been compared with those calculated by the non-empirical Hartree-Fock method and analysis of both experimental and theoretical electron densities and electrostatic potentials is described.

Acta Cryst. (1998). B54, 18-28 [doi:10.1107/S0108768197009208]

Investigation into the Crystal Structure of the Perovskite Lead Hafnate, PbHfO₃

D. L. Corker, A. M. Glazer, W. Kaminsky, R. W. Whatmore, J. Dec and K. Roleder

Synopsis: Polycrystalline neutron diffraction and low-temperature single crystal X-ray diffraction are used to investigate the room- temperature phase of lead hafnate, PbHfO₃. The octahedral distortion and cation shifts arising in this pseudo-cubic perovskite are compared with those of the technologically important material PbZrO₃.

Acta Cryst. (1998). B54, 29-34 [doi:10.1107/S0108768197009622]

Experimental Electron Density Study of NaH₂PO₄ at 30 K

M. Ichikawa, T. Gustafsson and I. Olovsson

Synopsis: The deformation electron density of NaH₂PO₄ has been studied at 30 K as a reference for the electron-density characteristics of hydrogen-bonded ferroelectrics containing phosphate ions and the effective charges were obtained.

Acta Cryst. (1998). B54, 35-40 [doi:10.1107/S0108768197012068]

Distribution of the M-M Distances in the Oxides of the Group 13 Elements and their Spinels and Delafossites

R. Isea, A. Vegas and A. Ramos-Gallardo

Synopsis: The M-M distances (M = Al, Ga, In, Tl), in their oxides, are not distributed uniformly, but present maxima at values near the corresponding distances in the pure metals.

Acta Cryst. (1998). B54, 41-49 [doi:10.1107/S0108768197012147]

Intermolecular Force-Field Parameters for Boron Hydrides

D. E. Williams and D. Gao

Synopsis: A new computer program, nbp, is used to fit a training set of 15 borane crystal structures with an (exp-6-1) intermolecular force field.

Acta Cryst. (1998). B54, 50-65 [doi:10.1107/S0108768197008677]

Intermolecular N-HO Hydrogen Bonding Assisted by Resonance. II. Self Assembly of Hydrogen-Bonded Secondary Enaminones in Supramolecular Catemers

V. Bertolasi, P. Gilli, V. Ferretti and G. Gilli

Synopsis: Structures of compounds containing the 2-en-3-amino-1-one heterodienic system are investigated; they form intermolecular N-HO resonance-assisted hydrogen bonds by which the molecules are connected in infinite chains. The effects of the substituents on the enaminonic systems and the chain morphologies are analyzed in order to discover crystal engineering rules to predict and interpret crystal packings.

Acta Cryst. (1998). B54, 66-72 [doi:10.1107/S0108768197009269]

Experimental Electron-Density Study of 4-Cyanoimidazolium-5-olate at 120 K

R. Bianchi, G. Gervasio and G. Viscardi

Synopsis: The experimental electron density study of 4-cyanoimidazolium-5-olate at 120 K shows details of its molecular mesoionic structure.

Acta Cryst. (1998). B54, 73-81 [doi:10.1107/S0108768197009440]

Nucleophile-Electrophile Interactions in 1,8-Disubstituted Naphthalenes: Structures of Three 1-Naphthaldehydes and a 1-Naphthyl Methyl Ketone

J. C. Gallucci, D. J. Hart and D. G. J. Young

Synopsis: Crystal structures of several 8-oxygenated 1-naphthaldehydes and 1-naphthyl methyl ketones indicate that the carbonyl group in the former approaches coplanarity with the naphthalene ring, while in the latter it approaches orthogonality. This difference in behavior is discussed in terms of steric effects and C-HO interactions.

Acta Cryst. (1998). B54, 82-93 [doi:10.1107/S0108768197010471]

Temperature-Dependent Phase Transitions in Two Crystalline Host-Guest Complexes Derived from Mandelic Acid

O. Hager, C. Foces-Foces, A. L. Llamas-Saiz and E. Weber

Synopsis: The crystal structures of two inclusion complexes of mandelic acid derivatives and DMF [(1) and (2)], which show reversible solid-solid phase transitions dependent on temperature, have been established for both crystal forms [170 and 250 K, and 170 and 270 K] of (1) and (2), respectively.

short communications

Acta Cryst. (1998). B54, 94-96 [doi:10.1107/S0108768197010264]

Structural and computational analysis of published neutron diffraction data show that crystalline vitamin B₁₂ coenzyme contains a strong intramolecular N-HPh hydrogen bond

E. B. Starikov and T. Steiner

Synopsis: The neutron diffraction crystal structure of vitamin B₁₂ coenzyme contains an intramolecular N-HPh hydrogen bond with an energy of ca 16.7 kJ mol^-1.