Non-innocent ligands provide alternative pathways for heterolytic bond cleavage in catalytic which can facilitate catalytic transformations through lower energy elementary steps available at a single metal site. Steps involving non-innocent ligands can also access low coordinate configurations, for example, to activate C–H bonds. They have been utilized with early metals to activate such bonds. This presentation will discuss the synthesis of a new class of ligand that combines a cyclopentadienyl group, and oxazoline which can be conjugated to a benzylic functionality. As a result, the ligand can access both monovalent X-type coordination and divalent X2-type coordination via an oxazolide configuration. We have prepared a series of these ligands, containing achiral and chiral oxazolines, and then studied their coordination chemistry in zirconium amido complexes. The compounds C5H5–CMe2–CPhH–OxR (OxR: OxMe2= 4,4-dimethyl-2-oxazoline, OxiPr = (S)-2-benzyl-4-iso-propyl-2-oxazoline, OxtBu = (S)-2-benzyl-4-tert-butyl-2-oxazoline) are synthesized from dimethylfulvene and PhCH2–OxMe2, PhCH2–OxiPr, and PhCH2–OxtBu, respectively. Reaction of C5H5–CMe2–CPhH–OxMe2 and Zr(NMe2)4 gives mixture of (C5H4CMe2CPhOxMe2)Zr(NMe2)2 and (C5H4CMe2CPhOxMe2)Zr(NMe2)3. Similarly, reaction of C5H5–CMe2–CPhH–OxiPr and Zr(NMe2)4 provides mixture of (C5H4CMe2CPhOxiPr)Zr(NMe2)2 and (C5H4CMe2CPhOxiPr)Zr(NMe2)3 . Both reactions could eliminate HNMe2 to give bisamide complexes. In contrast, C5H5–CMe2–CPhH–OxtBu and Zr(NMe2)4 gives only (C5H4CMe2CPhOxtBu)Zr(NMe2)3. We hypothesize the steric hindrance is responsible for the lack of elimination of HNMe2 in (C5H4CMe2CPhOxtBu)Zr(NMe2)3.

Synthesis and characterization of mono(oxazoline)-substituted cyclopentadienyl zirconium complexes

2019 Fall National Meeting

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