Characterization of Diastereomeric Equilibria of Pseudotetrahedral Bis[(R or S)‐N‐1‐(Ar)Ethylsalicylaldiminato‐κ(2)N,O]zinc(II) with Λ/Δ‐Chirality‐At‐Metal Induction

A family of bis[(R or S)‐N‐1‐(Ar)ethylsalicylaldiminato‐κ(2)N,O]‐Δ/Λ‐zinc(II) {Ar=C(6)H(5) (ZnRL(1) or ZnSL(1)), p‐CH(3)OC(6)H(4) (ZnRL(2) or ZnSL(2)) and p‐ClC(6)H(4) (ZnRL(3) or ZnSL(3))} compounds was synthesized and investigated by multiple methods. They feature Λ/Δ‐chirality‐at‐metal induction along the pseudo‐C (2) axis of the molecules. The chirality induction is quantitative in the solid state, explored by X‐ray crystallography and powder X‐ray diffraction (PXRD), where R or S‐ligated complexes diastereoselectively yield Λ or Δ‐configuration at the metal. On the other hand, Λ and Δ‐diastereomers co‐exist in solution. The Λ⇆Δ equilibrium is solvent‐ and temperature‐dependent. Electronic circular dichroism (ECD) spectra confirm the existence of a diastereomeric excess of Λ‐ZnRL(1−3) or Δ‐ZnSL(1−3) in solution. DSC analysis reveals thermally induced irreversible phase transformation from a crystalline solid to an isotropic liquid phase. ECD spectra were reproduced by DFT geometry optimizations and time‐dependent DFT (TD‐DFT) calculations, providing ultimate proof of the dominant chirality atmetal in solution.