Improved Syntheses and Expanded Analyses of the Enantiomerically Enriched Chiral Cobalt Complexes Co(en)3I3 and Co(diNOsar)Br3

Abstract

This communication is a collection of additions and modifications to two previously published classic inorganic synthesis laboratory experiments. The experimental protocol for the synthesis and isolation of enantiomerically enriched Λ-(or Δ-)Co(en)3I3 has been modified to increase reproducibility, yield, and enantiomeric excess. A computational component including molecular visualizations, model building, and energy minimization may be added to teach about the conformers that are formed as a result of λ and δ twists of the ligands. Modification of a second experiment for the synthesis of a Sargeson encapsulation product (Λ-(or Δ-)Co(diNOsar)Br3) from enantiomerically enriched Λ-(or Δ-)Co(en)3I3 includes advanced undergraduate analytical techniques including COSY, HMQC (or HETCOR), and NOESY NMR experiments, molecular visualizations, and CD spectroscopy for the characterization of products. Synthesis of a deuterated d12-Co(diNOsar)Br3 (which facilitates NMR assignments) is also described.