eprintid: 1458752 rev_number: 34 eprint_status: archive userid: 608 dir: disk0/01/45/87/52 datestamp: 2014-12-20 09:08:57 lastmod: 2021-10-04 01:24:00 status_changed: 2014-12-20 09:08:57 type: article metadata_visibility: show item_issues_count: 0 creators_name: Fortes, AD creators_name: Wood, IG creators_name: Alfè, D creators_name: Hernández, ER creators_name: Gutmann, MJ creators_name: Sparkes, HA title: Structure, hydrogen bonding and thermal expansion of ammonium carbonate monohydrate. ispublished: pub divisions: UCL divisions: B04 divisions: C06 divisions: F57 keywords: Raman spectroscopy, ammonium carbonate, density functional theory, neutron diffraction note: This is an open-access article distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited. 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) Å(3) [ρcalc = 1281.8 (7) kg m(-3)] at 10 K. The single-crystal data collected at 10 and 100 K are complemented by X-ray powder diffraction data measured from 245 to 273 K, Raman spectra measured from 80 to 263 K 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 273 K; above 273 K, 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 (EHB ≃ 30-40 kJ mol(-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 ∼ 36 kJ mol(-1). The c-axis exhibits negative thermal expansion, but the thermal expansion behaviour of the a and b axes is ormal. date: 2014-12 official_url: http://dx.doi.org/10.1107/S205252061402126X vfaculties: VMPS oa_status: green full_text_type: pub language: eng primo: open primo_central: open_green article_type_text: Journal Article, Research Support, Non-U.S. Gov't verified: verified_manual elements_source: PubMed elements_id: 999919 doi: 10.1107/S205252061402126X pii: S205252061402126X lyricists_name: Alfe, Dario lyricists_name: Fortes, Andrew lyricists_name: Wood, Ian lyricists_id: DALFE65 lyricists_id: AFORT20 lyricists_id: IGWOO38 full_text_status: public publication: Acta Crystallogr B Struct Sci Cryst Eng Mater volume: 70 number: Pt 6 pagerange: 948 - 962 event_location: England citation: Fortes, AD; Wood, IG; Alfè, D; Hernández, ER; Gutmann, MJ; Sparkes, HA; (2014) Structure, hydrogen bonding and thermal expansion of ammonium carbonate monohydrate. Acta Crystallogr B Struct Sci Cryst Eng Mater , 70 (Pt 6) 948 - 962. 10.1107/S205252061402126X <https://doi.org/10.1107/S205252061402126X>. Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/1458752/1/eb5035-1.pdf