Density functional theory calculations with the B3LYP hybrid functional have been performed to determine the equilibrium structures of a representative series of thiono-, oxo,thiono-, dioxo-, and dithiono-derivatives of sparteine. All these molecules except 2,13-dioxo-sparteine adopt one most stable conformation or exhibit a marked preference for one of the two lowest-energy conformations of the parent sparteine (with each functionalized ring distorted as a sofa or half-chair). 2,13-Dioxo-sparteine is instead predicted to exist as a nearly 1:1 mixture of ‘‘ring C chair’’ and ‘‘ring C boat’’ conformers in solution. The theoretical structural models are consistent with the available X-ray experimental results. The electronic structure of these bis-quinolizidine alkaloids has been studied by measuring and calculating important features of their NMR and photoelectron spectra
Titolo: | A combined spectroscopic and theoretical study of oxo- and thiono-sparteines |
Autori: | |
Data di pubblicazione: | 2005 |
Rivista: | |
Abstract: | Density functional theory calculations with the B3LYP hybrid functional have been performed to determine the equilibrium structures of a representative series of thiono-, oxo,thiono-, dioxo-, and dithiono-derivatives of sparteine. All these molecules except 2,13-dioxo-sparteine adopt one most stable conformation or exhibit a marked preference for one of the two lowest-energy conformations of the parent sparteine (with each functionalized ring distorted as a sofa or half-chair). 2,13-Dioxo-sparteine is instead predicted to exist as a nearly 1:1 mixture of ‘‘ring C chair’’ and ‘‘ring C boat’’ conformers in solution. The theoretical structural models are consistent with the available X-ray experimental results. The electronic structure of these bis-quinolizidine alkaloids has been studied by measuring and calculating important features of their NMR and photoelectron spectra |
Handle: | http://hdl.handle.net/11368/1894721 |
Digital Object Identifier (DOI): | http://dx.doi.org/10.1016/j.chemphys.2005.01.013 |
Appare nelle tipologie: | 1.1 Articolo in Rivista |