UCL  IRIS
Institutional Research Information Service
UCL Logo
Please report any queries concerning the funding data grouped in the sections named "Externally Awarded" or "Internally Disbursed" (shown on the profile page) to your Research Finance Administrator. Your can find your Research Finance Administrator at https://www.ucl.ac.uk/finance/research/rs-contacts.php by entering your department
Please report any queries concerning the student data shown on the profile page to:

Email: portico-services@ucl.ac.uk

Help Desk: http://www.ucl.ac.uk/ras/portico/helpdesk
Publication Detail
Structure, hydrogen bonding and thermal expansion of ammonium carbonate monohydrate
  • Publication Type:
    Journal article
  • Publication Sub Type:
    Journal Article
  • Authors:
    Fortes AD, Wood IG, Alfè D, Hernández ER, Gutmann MJ, Sparkes HA
  • Publication date:
    01/12/2014
  • Pagination:
    948, 962
  • Journal:
    Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials
  • Volume:
    70
  • Issue:
    6
  • Status:
    Published
  • Print ISSN:
    2052-5192
Abstract
We have determined the crystal structure of ammonium carbonate monohydrate, (NH4)2CO3·H2O, using Laue single-crystal diffraction methods with pulsed neutron radiation. The crystal is orthorhombic, space group Pnma (Z = 4), with unit-cell dimensions a = 12.047(3), b = 4.453(1), c = 11.023(3)Å and V = 591.3(3)Å3 [ρcalc = 1281.8(7)kgm-3] at 10K. The single-crystal data collected at 10 and 100K are complemented by X-ray powder diffraction data measured from 245 to 273K, Raman spectra measured from 80 to 263K and an athermal zero-pressure calculation of the electronic structure and phonon spectrum carried out using density functional theory (DFT). We find no evidence of a phase transition between 10 and 273K; above 273K, however, the title compound transforms first to ammonium sesquicarbonate monohydrate and subsequently to ammonium bicarbonate. The crystallographic and spectroscopic data and the calculations reveal a quite strongly hydrogen-bonded structure (E HB ≃ 30-40kJmol-1), on the basis of H⋯O bond lengths and the topology of the electron density at the bond critical points, in which there is no free rotation of the ammonium cation at any temperature. The barrier to free rotation of the ammonium ions is estimated from the observed librational frequency to be ∼36kJmol-1. The c-axis exhibits negative thermal expansion, but the thermal expansion behaviour of the a and b axes is ormal.
Publication data is maintained in RPS. Visit https://rps.ucl.ac.uk
 More search options
UCL Researchers
Author
Dept of Earth Sciences
Author
Dept of Earth Sciences
Author
Dept of Earth Sciences
University College London - Gower Street - London - WC1E 6BT Tel:+44 (0)20 7679 2000

© UCL 1999–2011

Search by