ISSN:
0009-2940
Keywords:
Selenolate
;
Aminoselenolate
;
Lithium compound i Ab initio calculations
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Lithium 2,2,6,6-tetramethylpiperidide inserts elemental selenium into its Li-N bond with the formation of lithium 2,2,6,6-tetramethylpiperidinoselenolate 1. In the crystal 1 is an unsymmetric dimer. One lithium atom is coordinated tetrahedrally by two molecules of tetrahydrofuran and two selenium atoms, the other lithium atom exhibits an approximately rectangular-planar coordination by two N,Se-chelating groups. The lithium atoms are bridged by two selenium atoms thus forming a planar Li2Se2 core. Ab initio Hartree-Fock calculations show 1 and the hypothetical symmetric dimer 2 to be of equal energy, whereas the non-chelated dimer 3 is of distinctly higher energy. Exclusive crystallization of 1 is most likely a consequence of its large dipole moment of 6.18 D. Calculations also show that the deformation of the observed geometry around the uniquely coordinated lithium atom in 1 towards distorted tetrahedral or complete planarity leads to an increase of energy. Excessive charge transfer from selenium to nitrogen explains the overwhelming tendency for the N,Se-chelating bonding.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19971300120
Permalink
