Investigations into dianionic scorpionate ligands and their metal complexes

Abstract

Ligand design helps to define reactivity in coordination complexes and organometallic chemistry. Ligand characteristics greatly influence the reactivity of transition metal complexes and simple changes in the steric or electronic properties of a ligand can drastically affect the activity and selectivity of a catalyst. Scorpionate ligands are an easily tunable and display flexible binding modes in that they can act as bidentate or tridentate donors. In literature scorpionate ligands with charged donors are underrepresented and this is an area with great potential to explore and discover new organometallic complexes with novel reactivity. Inspired by scorpionate ligands and phenolate ligands throughout the literature, a set of eight neutral ligands were synthesized and utilized in the generation of metal complexes. These novel ligands were diphenolate ligands with a nitrogen or oxygen containing tail. The steric hinderance of these structures was varied using the ortho substituents on the phenol groups. The various tails also allowed the binding strength of the ligands to be varied. Studies on the activity of the complexes bearing these scorpionate ligands were performed. The effect of the steric size of the ligands as well as binding strength of the tail were investigated.