
%0 Journal Article
%A Becker, HD 
%A Kildea, JD 
%A Patrick, VA 
%A Skelton, BW 
%A White, AH 
%T Molecular-Structures and Conformations of 9,9'-Anthroin ('&#945;' and '&#946;' Forms), 9,9'-Anthroin Acetate, and Some Related Benzoin Derivatives
%J Australian Journal of Chemistry
%D 1991/12/01
%V 44
%N 12
%P 1737-1747
%K 
%R https://doi.org/10.1071/CH9911737
%U https://www.publish.csiro.au/paper/CH9911737 
%X The molecular conformations of 9,9&#8242;-anthroin (two forms, '&#945;' and '&#946;') and its acetate, as well as those of the acetates of benzoin and p- anisoin , have been studied by X-ray diffraction methods and found to display similar characteristics in respect of the COCO moiety. The conformation of 1,2-diaryl acyloins is characterized by a small torsion angle (10-24&#176;) about the central four-atom fragment O=C-C-O, and the intramolecular distance between the two oxygen atoms does not exceed 2.8 &#506;. The torsion angle about the three-bond segment Ar-C-C-Ar is in all cases smaller than 90&#176;. In benzoin and its derivatives, the arylcarbonyl group deviates from planarity by 4-12&#176;. In the cases of &#946; 9,9&#8242;-anthroin and its acetate, the carbonyl group is twisted out of the plane of the anthracene moiety by 75&#176;, and the two anthracene &#960;-systems are in an overlapping arrangement; for &#945;-anthroin, despite the presence of disorder in the COCOH moiety, a similar disposition can be inferred, indicative overall that, for such species, hydrogen bonding is not necessarily dominant in determining conformation. 
