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Inne
Relationship between electron difference-density distribution, planarity of the >N-O groups and intermolecular hydrogen bond systems in crystals of stable nitroxide radicals.
Autorzy
Rok wydania
1997
Czasopismo
Journal of Molecular Structure
Numer woluminu
412
Strony
27-37
DOI
10.1016/S0022-2860(97)00010-0
Kolekcja
Język
Angielski
Typ publikacji
Artykuł
The electron density distribution calculated for 2,2,6,6-tetramethyl-1-piperidinyloxy (1), 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy (2) and 3-carbamoyl-2,2,5,5-tetramethyl-3-pyrrolin-1-yloxy (3) free radicals on the basis of low-temperature X-ray single crystal diffraction experiments revealed some differences in region of the >N–O groups. Generally, the experimental bonding density along the axis of the N–O bond is relatively low and asymmetric in cases of the pyramidal geometry of the aminoxyl group (1 and 2) and almost symmetrical for the planar geometry (3). The shape and distribution of electron densities in the region of the oxygen lone-pairs suggest that this atom is sp3 hybridized but the spatial orientation of these maxima depends on hydrogen bond interactions (>N–O⋯H) in studied crystals. Also the relation between the direction of the relatively strong hydrogen bonds (O⋯H<2.2 Å) and the geometry of aminoxyl groups analysed for crystal structures collected in the Cambridge Structural Database showed that these interactions can affect the aminoxyl group geometry.
Adres publiczny
https://doi.org/10.1016/S0022-2860(97)00010-0
