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Strukturen und Moleküleigenschaften sterisch überfüllter Moleküle, 43. Triisopropylammonium‐chlorid: Einkristallstruktur und Berechnungen zur Protonierung des p‐Typ‐Stickstoff‐Elektronenpaares
Author(s) -
Bock Hans,
Göbel Ilka,
Bensch Wolfgang,
Solouki Bahman
Publication year - 1994
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19941270211
Subject(s) - chemistry , steric effects , protonation , crystallography , lone pair , isopropyl , molecule , crystal structure , hydrogen bond , stereochemistry , medicinal chemistry , ion , organic chemistry
Structures and Molecular Properties of Sterically Overcrowded Molecules 43 [1] . — Triisopropylammonium Chloride: Single‐Crystal Structure and Calculations Concerning the Protonation of the p‐Type Nitrogen Electron Pair [2] The protonation of triisopropylamine, which contains an almost planar NC 3 skeleton of C 3 symmetry and, therefore, a p‐type N electron pair, with HCl in methanol causes severe structural perturbation due to extreme steric overcrowdedness: the single‐crystal structure determination (orthorhombic Pbca , Z = 8) proves that the molecular symmetry is reduced to C 5 by the rotation of one isopropyl group around its CN axis by almost 90° and the decrease of the angles CNC from 119° each to 115, 115 and 111°, respectively. The Cl ⊖ ⃛(H)N hydrogen bond distance of 315 pm is presumably slightly increased by steric overlap of the van der Waals radii of Cl ⊖ and one of the three adjacent methyl groups. The protonation of the p‐type lone pair of triisopropylamine including the pyramidalization of the nitrogen centre and the twist of one isopropyl group can be simulated by a one‐dimensional energy hypersurface calculation, if H ⊕ attack outside the C 3 axis is assumed.