B. Goldfuss, Frank Eisenträger
Jul 12, 2000
Citations
0
Influential Citations
20
Citations
Journal
Australian Journal of Chemistry
Abstract
The X-ray crystal structure of dimeric lithium (1R,2R,4S)-exo-2-[o-(dimethylaminomethyl)phenyl]-1,3,3-trimethylbicyclo[2.2.1]heptan-endo-2-olate (2-Li)2 exhibits lithium ions with pyramidal environments of oxygen and nitrogen atoms. Ab initio (RHF/6-31+G*) computations of dimeric trimethylamine-coordinated lithium methoxide show that electrostatics disfavour the pyramidal distortions at lithiums in (2-Li)2 by 5.0 kJ/mol. ONIOM(B3LYP/6-31+G*:UFF) computations of (2-Li)2 as well as of (2-Li-b)2 and (2-Li-c)2, with one or two planar constrained lithium ion environments, reveal destabilizations of 32.2 and 97.5 kJ/mol, respectively, upon planarization at lithium. The destabilizations of planar coordinated lithiums in (2-Li-b)2 and (2-Li-c)2 arise from repulsions between methylamino groups and bicycloheptane moieties and give rise to the observed pyramidal environments at the lithiums in the X-ray crystal structure of (2-Li)2.