TY - JOUR
T1 - Tautomerism in acyl-pyrazolones and in a novel photolysis product—importance and impact of the accurate localization of hydrogen atoms in crystal structures
AU - Malaspina, Lorraine A.
AU - White, Allan H.
AU - Wege, Dieter
AU - Tolmie, Michael B.
AU - Skelton, Brian W.
AU - Grabowsky, Simon
PY - 2017/10
Y1 - 2017/10
N2 - Acyl-pyrazolones exist in four different tautomeric forms (two keto and two enol) in crystal structures. Routine crystal structure refinements using an independent atom model and routine isolated-molecule calculations fail in locating the mobile hydrogen atoms accurately in 22 investigated acyl-pyrazolone examples. However, a combination of both within the framework of quantum crystallography represented by the method of Hirshfeld atom refinement accurately locates the mobile hydrogen atom in a resonance-assisted hydrogen bond of title compound 3, a novel photolysis product. The impact of the hydrogen atom position on the resonance system of the non-hydrogen framework of the various tautomers is discussed, and the importance of intermolecular interactions for the positioning of the hydrogen atom is highlighted.
AB - Acyl-pyrazolones exist in four different tautomeric forms (two keto and two enol) in crystal structures. Routine crystal structure refinements using an independent atom model and routine isolated-molecule calculations fail in locating the mobile hydrogen atoms accurately in 22 investigated acyl-pyrazolone examples. However, a combination of both within the framework of quantum crystallography represented by the method of Hirshfeld atom refinement accurately locates the mobile hydrogen atom in a resonance-assisted hydrogen bond of title compound 3, a novel photolysis product. The impact of the hydrogen atom position on the resonance system of the non-hydrogen framework of the various tautomers is discussed, and the importance of intermolecular interactions for the positioning of the hydrogen atom is highlighted.
KW - Hirshfeld atom refinement
KW - Hydrogen atom parameters
KW - Photolysis
KW - Resonance-assisted hydrogen bond
KW - Tautomerism
UR - http://www.scopus.com/inward/record.url?scp=85026894054&partnerID=8YFLogxK
U2 - 10.1007/s11224-017-1005-0
DO - 10.1007/s11224-017-1005-0
M3 - Article
AN - SCOPUS:85026894054
VL - 28
SP - 1343
EP - 1357
JO - Structural Chemistry: computational and experimental studies of chemical and biological systems
JF - Structural Chemistry: computational and experimental studies of chemical and biological systems
SN - 1040-0400
IS - 5
ER -