Theoretical determination of molecular structure and conformation

High resolution Fourier transform infrared spectra and analysis of the ν14, ν15 and ν16 bands of azetidine

“…The far infrared data was later re-analyzed by Robiette et al [11] and found to be consistent with a single well asymmetric potential with the equatorial conformer being the only stable structure. This is in agreement with ab initio calculations [12,13], Raman intensities [14] and a subsequent far infrared study [15]. The microwave and electron diffraction experiments of Günther et al [16] confirmed the presence of the equatorial conformer and determined its structure to have a ring puckering angle of 29.7°although their microwave spectrum also contained a weak unassigned feature which was thought to be due to the axial conformer.…”

Extension of the Karplus Relationship for NMR Spin-Spin Coupling Constants to Nonplanar Ring Systems: Pseudorotation of Tetrahydrofuran

“…According to the CP theory of ring puckering, the out-of-plane coordinates z j of atom j=1,...,5 of any five-membered ring conformation are given by [34][35][36][37][38][39][40][41] …”

“…Finally, the projected ring is partitioned into segments, for which the coordinates x j , y j are calculated according to a procedure described by Cremer [37]. The use of the ring puckering coordinates has the advantage [40,41] that the geometry of puckered forms of THF with a given value of φ (or q and φ) can be optimized even if these forms do not occupy a stationary point of the CES. This would not be possible when using Cartesian or internal coordinates [37].…”

Hydrogen bonding in 3-azetidinol. I. Crystal and molecular structure

“…Force-field (Profeta & Allinger, 1985) and several ab initio (Dutler, Rauk & Sorensen, 1987;Catalan, Mo & Yanez, 1978;Cremer, Dorofeeva & Mastryukov, 1981) calculations have been reported for azetidine. We have performed ab initio calculations on 3-azetidinol using the GAUSSIAN86 (Frisch et.…”