Journal Article

FZJ-2015-03507

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Single-Crystal Neutron Diffraction Study on Guanidine, CN $_{3}$ H $_{5}$

Sawinski, P. K. ; Meven, M.FZJ* ; Englert, U. ; Dronskowski, R. (Corresponding Author)

2013
ACS Publ. Washington, DC

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Please use a persistent id in citations: doi:10.1021/cg400054k

Abstract: Pure guanidine crystallizes in the orthorhombic space group Pbca (no. 61) and a = 8.5022(2) Å, b = 9.0863(2) Å, c = 15.6786(4) Å at 100 K, Z = 16, with two Y-shaped molecules in the asymmetric unit. The compound features a three-dimensional network of classical N–H···N hydrogen bonds. Here, we present the results of a single-crystal neutron diffraction study, performed at two different temperatures (100 and 273 K). The data quality obtained at the HEiDi instrument (FRM II, Munich) allowed to derive accurate positional and anisotropic displacement parameters (ADP) for all the atoms, including H. The experimental hydrogen positions confirm a model derived from theory. On the basis of the displacement parameters, a TLS analysis of thermal motion proves that the guanidine molecules behave in good approximation as rigid bodies and essentially undergo libration. The unusual temperature behavior of one C–N bond found in a preceding single-crystal X-ray study is an artifact going back to this rigid-body movement. The existence of various hydrogen bonds also manifests from a well-resolved IR spectrum, which was analyzed in terms of individual vibrations on the basis of quasi-harmonic ab initio phonon calculations.

Keyword(s): Basic research (1st) ; Others (1st) ; Life Science and Health (1st) ; Crystallography (2nd) ; Chemistry (2nd)

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Contributing Institute(s):

1. Streumethoden (JCNS-2)
2. Streumethoden (PGI-4)
3. JARA-FIT (JARA-FIT)
4. JCNS-FRM-II (JCNS (München) ; Jülich Centre for Neutron Science JCNS (München) ; JCNS-FRM-II)

Research Program(s):

1. 422 - Spin-based and quantum information (POF2-422) (POF2-422)
2. 424 - Exploratory materials and phenomena (POF2-424) (POF2-424)
3. 542 - Neutrons (POF2-542) (POF2-542)
4. 544 - In-house Research with PNI (POF2-544) (POF2-544)
5. 54G - JCNS (POF2-54G24) (POF2-54G24)

Experiment(s):

1. HEiDi: Single crystal diffractometer on hot source (SR9b)

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Database coverage:
; Current Contents - Physical, Chemical and Earth Sciences ; IF < 5 ; JCR ; NCBI Molecular Biology Database ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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