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Conformational Flexibility of the Acetoxyphenyl Group Studied by Statistical Analysis of Crystal Structure Data
Author(s) -
Hummel Wolfgang,
Roszak Aleksander,
Bürgi HansBeat
Publication year - 1988
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19880710539
Subject(s) - chemistry , perpendicular , steric effects , group (periodic table) , crystallography , ring (chemistry) , atom (system on chip) , rotation (mathematics) , bond length , crystal structure , planar , crystal (programming language) , stereochemistry , geometry , mathematics , computer graphics (images) , organic chemistry , computer science , embedded system , programming language
The preferred conformation of the acetoxyphenyl fragment shows a planar acctoxy (AcO) group perpendicular to the Ph ring. Steric hindrance strongly limits and affects rotation about the COCOCH 3 bond: if the A c O group twists away from its perpendicular conformation, the carbonyl oxygen moves to keep the nonbonded distance to the atoms in ortho ‐position maximal. This is achieved by some twisting about the OCOCH 3 bond correlated with angle bending at the ipso ‐C‐atom and ester O‐atom. The maximum observed deviation away from the perpendicular conformation is ∼ 47°. In the case of one or two ortho ‐hydrogens, deviations of the AcO group from the perpendicular conformation tend to be larger than in the case of two substituents.