Chiral tridentate bis(oxazol-2-ylimino) isoindoline-based pincer ligands: isolation and characterization deligation from prepared Cd-ligand complexes

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 5; no. 29; pp. 141 - 149
• Main Authors: Zivkovic, Kristina, Baldauf, Lilia M, Cryder, Jessica L, Villaseñor, Alexa, Reyes, Valeria, Bernier, Lauren E, Thomas, Theresa J, O'Toole, Maxwell, Fulton, Kayleen, Moore, Curtis E, Rheingold, Arnold L, Daley, Christopher J. A
• Format: Journal Article
• Published: 27.07.2021
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/d0dt02531c

The first isolation and structural characterization of a series of chiral trinitrogen 1,3-bis(4,5-dihydrooxazol-2-ylimino)isoindoline-based pincer ligands are reported. Cadmium complexes, isolated as Cd(L 2 X) 2 where L 2 X is the deprotonated form of L 2 XH = 1,3-bis(4,5-dihydro-4-( R )-phenyloxazol-2-ylimino)-isoindoline (( R , R )- 5 H) or 1,3-bis(4,5-dihydro-4-( S )-iso-propyloxazol-2-ylimino)isoindoline (( S , S )- 6 H) were prepared in situ via traditional or microwave-based techniques with the latter being more efficient but less able to be scaled up at this time. Ligands ( R , R )- 5 H and ( S , S )- 6 H were isolated via deligation from their respective cadmium complexes using a thiol-based ligand exchange protocol. The characterization of ligands and their respective cadmium complexes, in both the solid (X-ray crystallography) and solution (NMR spectroscopy) states are reported. Pd(( S , S )- 6 )(OAc) is reported as a proof-of-concept of the ability to prepare 1 : 1 ligand to metal ratio complexes that are believed to be necessary as potential enantioselective catalysts. Two-step synthesis of new chiral, bis(oxazol-2-ylimino) isodinoline-based pincer ligands for potential use in metal-mediated enantioselective catalysis reactions.