A neutron diffraction study of squaric acid (3,4-dihydroxy-3-cyclobutene-1,2-dione)
- 15 May 1977
- journal article
- research article
- Published by AIP Publishing in The Journal of Chemical Physics
- Vol. 66 (10) , 4405-4412
- https://doi.org/10.1063/1.433745
Abstract
A neutron diffraction study of squaric acid (C4H2O4; 3,4‐dihydroxy‐3‐cyclobutene‐1,2‐dione) at 25°C has been carried out. Space group P21/m, a=6.143(2), b=5.286(2), c=6.148(2) Å, β=89.96(2) °, Z=2. The structure has been refined with 67 variable parameters on 1026 reflections, comprising one hemisphere of the reciprocal lattice to yield a conventional crystallographic R value of 0.025. An anisotropic extinction correction was applied, and 66 reflections severely effected by extinction were not used in the final cycles of refinement. The squaric acid molecules are linked by strong hydrogen bonds to form infinite planar layers in the crystallographic mirror planes. The hydrogen bond lengths are H⋅⋅⋅O 1.034 and O⋅⋅⋅O 2.554 Å, the O−H⋅⋅⋅O angle is 177.5°. Average intramolecular bond distances are C–O 1.288, C=O 1.229, C–C 1.500 and 1.462, and C=C 1.414 Å.Keywords
This publication has 18 references indexed in Scilit:
- The experimental charge density in sulfur-containing molecules. A study of the deformation electron density in sulfamic acid at 78 K by X-ray and neutron diffractionActa Crystallographica Section B: Structural Science, Crystal Engineering and Materials, 1977
- The Crystal Structure Determination of Lithium 2-Hydroxy-3,4-dioxocyclobut-1-en-1-olate Monohydrate, LiHC4O4.H2O.Acta Chemica Scandinavica, 1976
- Valence electron distribution in perdeuterio-.alpha.-glycylglycine. High-resolution study of the peptide bondJournal of the American Chemical Society, 1975
- The hydrated proton H+(H2O)n. III. A neutron diffraction study of deuterated paratoluene sulfonic acid monohydrate, D3O+CH3C6H4SO3−, and an analysis of the effect of deuteration on oxonium ion geometryThe Journal of Chemical Physics, 1973
- The Crystal Structure of Squaric Acid.Acta Chemica Scandinavica, 1973
- Electron density distribution in cyanuric acid. II. Neutron diffraction study at liquid nitrogen temperature and comparison of X-ray neutron diffraction resultsActa Crystallographica Section B: Structural Science, Crystal Engineering and Materials, 1971
- The infrared and Raman spectra of crystalline squaric acidSpectrochimica Acta Part A: Molecular Spectroscopy, 1970
- Anisotropic extinction corrections in the Zachariasen approximationActa Crystallographica Section A, 1970
- Neutron diffraction study of hydrogen bonding and thermal motion in deuterated α and β oxalic acid dihydrateActa Crystallographica Section B: Structural Science, Crystal Engineering and Materials, 1969
- Multiple spectrometer control by computerNuclear Instruments and Methods, 1966