Journal Article

FZJ-2019-00337

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Proton disorder in a short intramolecular hydrogen bond investigated by single-crystal neutron diffraction at 2.5 and 170 K

Truong, K.-N. (Corresponding author) ; Meven, M.MLZ*FZJ*RWTH* ; Englert, U. (Corresponding author)

2018
Wiley-Blackwell Oxford

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Please use a persistent id in citations: doi:10.1107/S2053229618015164

Abstract: The substituted acetyl­acetone 3-[2-(pyridin-4-yl)eth­yl]pentane-2,4-dione, C12H15NO2, (1), with an ethyl­ene bridge between the acetyl­acetone moiety and the heteroaromatic ring, represents an attractive linker for mixed-metal coordination polymers. In the crystal, (1) adopts an anti­periplanar conformation with respect to the C—C bond in the central ethyl­ene group and almost coplanar acetyl­acetone and pyridyl groups. The ditopic mol­ecule exists as the enol tautomer, with proton disorder in the short intra­molecular hydrogen bond. Single-crystal neutron diffraction at 2.5 K indicated site occupancies of 0.602 (17) and 0.398 (17). The geometry of the acetyl­acetone moiety is in agreement with such a site preference of the bridging hydrogen: the O atom associated with the preferred H-atom site subtends the longer [1.305 (2) Å] and the more carbonyl-like O atom the shorter [1.288 (2) Å] C—O bond. Based on structure-factor calculations for the alternative H-atom sites, reflections particularly sensitive for proton distribution were identified and measured in a second neutron data collection at 170 K. At this temperature, 546 independent neutron intensities were used to refine positional and isotropic displacement parameters for a structure model in which parameters for C and O atoms were constrained to those obtained by single-crystal X-ray diffraction at the same temperature. The site occupancies for the disordered proton do not significantly differ from those at 2.5 K.

Keyword(s): Chemical Reactions and Advanced Materials (1st) ; Crystallography (2nd) ; Chemistry (2nd)

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Contributing Institute(s):

1. JCNS-FRM-II (JCNS-FRM-II)
2. Heinz Maier-Leibnitz Zentrum (MLZ)
3. Streumethoden (JCNS-2)

Research Program(s):

1. 6G4 - Jülich Centre for Neutron Research (JCNS) (POF3-623) (POF3-623)
2. 6G15 - FRM II / MLZ (POF3-6G15) (POF3-6G15)

Experiment(s):

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

Appears in the scientific report 2018

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Database coverage:
; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; IF >= 5 ; JCR ; NCBI Molecular Biology Database ; Nationallizenz ; PubMed Central ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Web of Science Core Collection

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