N,N'-Bis-silylated Lithium Aryl Amidinates: the Gradual Transition of Coordination Mode From σ Towards π Originated by Crystal Packing Interactions
Written by Sinai Aharonovich
Sinai Aharonovich, Moshe Kapon, Mark Botoshanski, and Moris S. Eisen
Schulich Faculty of Chemistry and Institute of Catalysis Science and Technology, Kyriat Hatechnion, Haifa, 32000, Israel
Lithium amidinates, LiN(R1)C(R2)NR3, are useful synthons in organic and organometallic chemistry. These applications in addition to the wide use of lithium amidinates as ligand transfer reagents in the preparation of amidinate complexes of p, d, and f block elements has raised growing interest in the last two decades in the structural study of these complexes.
In this presentation nine lithium N, N'-bis(trimethylsilyl)amidinates-TMEDA complexes were synthesized and characterized. The solid state structures of the amidinates revealed several types of crystalline supramolecular structures, generated by the degree and nature of involvement of the amidinate π system in the intermolecular interactions. The π system was also found to play a significant role in the intramolecular bonding with the lithium center. This p bonding is obtained at the expense of the s bond, weakening it, whilst keeping the metal-ligand bond length almost invariable.