Diverse Coordinative Zinc Complexes Containing Amido-Pyridinate Ligands: Structural and Catalytic Studies

Abstract

In this work, zinc complexes containing amidopyridinate ligands substituted with different pendant arms have been described. Treatment of ligand precursors with ZnEt2 at a 1:1 ratio in THF yields zinc ethyl complexes (PyNC1Py)2(ZnEt)2 (1) and (PyNC2NMe2)2(ZnEt)2 (2), respectively. Complexes 1 and 2 show the same geometry as a distorted tetrahedron, but adopt different coordination behaviors supported by the ligands. Complex 1 represents a rare and a non-centrosymmetric mode, which the amido group bridges two zinc centers to form a six-membered ring. However, complex 2 shows a centrosymmetric mode, which the pyridine group links to the zinc centers to form an eight-membered ring. Recrystallization of complex 2 gives an additional complex (PyNC2NMe2)4Zn3(μ3-O) (3). We attempted to prepare zinc benzyl oxide complexes but afforded only a self-assembly cubane complex Zn7Et6(OBn)8 (4). All molecular structures 1–4 are characterized depending on both single-crystal X-ray and spectroscopic data. Furthermore, their catalytic properties toward the ring opening polymerization of ε-caprolactone and L-lactide, using benzyl alcohol as the initiation reagent, are under investigation.

Grignard reagents as deprotonation agents for oxazoline-amido-phenolate ligands: structural and catalytic implications with the role of halogen ions

“…11 These ligands have been extensively investigated for their potential coordination chemistry and catalytic activities, including metal complexes (Al, Mg, or Zn) with anilido-oxazolinate ligands, 12 as well as metal complexes (Al or Zn) with N -substituted pyridinate ligands. 13 These prepared complexes exhibited good performances in ROP reactions. In our recent research, we conducted an investigation involving non-symmetrical donating pairs of ligands, specifically the oxazoline-amido-phenolate ligand, and explored their potential coordination chemistry.…”