UBC Undergraduate Research

Striking the right balance: An exploration of novel protonolysis precursors for CpCr(LX) complexes Therrien, Jeffrey A.


Directed ortho-metallation is a convenient route to Li(Ar-L) salts (where Ar is an aryl group), which may be used to synthesize CpCr(Ar-L) complexes by salt metathesis with chromium dichloride and sodium cyclopentadienylide. Some of these complexes have precedent as effective protonolysis precursors to CpCr(LX) complexes (where LX is a bidentate monoanionic ligand), providing a clean and direct synthetic pathway to the exploration of various anionic, bidentate ligand sets. Through the course of this investigation several new CpCr(Ar-L) complexes were rationally designed and synthesized, revealing unanticipated and undesired reactivity modes regarding the targeted protonolysis reactions. This discovery, by providing insight into the protonolysis reaction mechanism, led to the development of new CpCr(L)(X) complexes (where L is a neutral monodentate ligand, and X is an anionic monodentate ligand) through a number of synthetic routes. X-ray diffraction analysis of single crystals obtained from the attempted synthesis of CpCr(Mes)(L) (where Mes is 2,4,6-trimethylphenyl) derivative revealed a dimerized structure, suggesting that the complex contains the sought-after property of neutral ligand lability. These complexes have shown promise as a protonolysis precursor to CpCr(LX) compounds previously found unobtainable by less subtle salt metathesis pathways.

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