Synthesis and structures of main group organometallic complexes with sterically bulky allyl ligands

Abstract

This work focuses on the synthesis and characterization of substituted allyl complexes of alkali metals and post-transition elements. The use of bulky trimethylsilyl substituents on the allyl ligands has afforded isolable and thermally stable compounds of lithium, sodium, potassium, zinc, and gallium. The discussion of the resulting structurally characterized allyl-metal complexes focuses on the variation in bonding modes displayed by the allyl ligand. An attempt is made to determine a set of quantitative guidelines which can be used to classify the bonding in these and other similar organometallic complexes. An additional interaction displayed by the group of alkali metal tris(allyl Œ)zincates described in this work is the propensity for cation-pi interactions between the pendant arms of the sigma-bonded allyl ligands and lithium, sodium, or potassium. This characteristic is explored both through experimental means (single crystal X-ray structure analysis and solution NMR spectroscopy) and through density functional theory calculations.