Rare earth metal oxazoline complexes in asymmetric catalysis

Abstract

Polydentate oxazolines have been employed as highly effective stereodirecting ligands for asymmetric catalysis with metals from across most of the periodic table. Despite their highly versatile coordination chemistry, the use of these ligands tends to be polarised towards late transition metals; their use with early transition metals and the f-elements is significantly less developed. This current article aims to review the coordination chemistry and catalytic applications of Group 3 and lanthanide complexes supported by ligands possessing oxazoline moieties. Oxazoline-containing ligands were first employed in molecular lanthanide catalysis as early as 1997, yet there is still a significant void in the chemical literature in this respect. The ligands generally employed include bis(oxazolinyl)methane ("BOX"), 2,6-bis(oxazolinyl)pyridine ("pybox"), 1,1,1-tris(oxazolinyl)ethane ("trisox"), and others. The complexes are employed in a wide-range of catalytic applications, especially in Lewis acid catalysis, but also in the stereospecific polymerisation of olefins.

Novel cationic rare earth metal alkyl catalysts for precise olefin polymerization

“…The acid–base reaction between the rare earth metal trialkyl complex Ln(CH 2 SiMe 3 ) 3 (THF) 2 and the (S,S)‐bis(oxazolinylphenyl)amine ligand in toluene at 25 °C afforded the chiral C 2 ‐symmetric (S,S)‐bis(oxazolinylphenyl)amido rare earth metal dialkyl complexes [(S,S)‐BOPA]Ln(CH 2 SiMe 3 ) 2 ( 6a , 6b ) ( 6a : Ln = Sc; 6b : Ln = Lu) in high yields, which are soluble in common organic solvents such as THF, toluene, and hexane [Fig. (e)].…”

Rare Earth Pincer Complexes: Synthesis, Reaction Chemistry, and Catalysis

“…In addition, studies concerning rare earth metals with diverse oxazoline-based ligands have been recently and comprehensively reviewed. Thus, the interested reader is encouraged to procure further insight from that source [146].…”

Scandium Complexes Bearing Bis(oxazolinylphenyl)amide Ligands: An Analysis of Their Reactivity, Solution‐State Structures and Photophysical Properties

“…Organometallic‐type complexes of the rare‐earth metals (including Group 3 and lanthanide elements) have been the focus of intense study for their functional behaviour, particularly in homogeneous catalysis . To expedite the development of functional rare‐earth complexes, we must first thoroughly probe their organometallic and coordination chemistry (including stoichiometric reaction chemistry) with a range of supporting ligand environments.…”

“…Such studies provide invaluable information relating to coordination geometries, ligand stability, and viable reaction pathways; all of which are crucial in understanding complex molecular processes. Whilst the coordination chemistry of the rare‐earth metals is generally well‐understood, there are still ligand classes that are under‐represented, as a fraction of the total knowledge‐base; oxazoline‐containing ligands are a pertinent example …”