Theoretical study of a series of alkyllithium clusters

The structural and energetic properties of a series of alkyllithium clusters (methyl, ethyl, n, iso-propyl, n, sec, tert-butyl) have been studied using density functional theory. Geometries and binding energies have been determined using the B3LYP functional and a polarised double zeta basis set. Geometries are found in good agreement with the available experimental data when the corresponding crystals are built from non-interacting clusters. The polyhedral hexameric clusters appear to be the most stable structures except for tert-butyllithium for which the polyhedral tetramer is favored. This behaviour is related to the high steric hindrance in the tert-butyllithium hexamers and the apolar character of their Li-alkyl bonds. (C) 2003 Published by Elsevier B.V.