%0 Journal Article
%A Truong, Khai-Nghi
%A Meven, Martin
%A Englert, Ulli
%T Proton disorder in a short intramolecular hydrogen bond investigated by single-crystal neutron diffraction at 2.5 and 170 K
%J Acta crystallographica / C Structural Chemistry Section C
%V 74
%N 12
%@ 2053-2296
%C Oxford
%I Wiley-Blackwell
%M FZJ-2019-00337
%P 1635 - 1640
%D 2018
%X 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.
%F PUB:(DE-HGF)16
%9 Journal Article
%$ pmid:30516147
%U <Go to ISI:>//WOS:000452192900010
%R 10.1107/S2053229618015164
%U https://juser.fz-juelich.de/record/859484