Diastereoselective Axial-to-Chelate-Puckering Chirality Transfer in cis -[PtCl2(DABN)] Complexes

Abstract

Abstract Axially chiral 1,1′-binaphthalene-2,2′-diamine (DABN) was used to control chelate-ring puckering in cis-[PtCl2(DABN)] complexes. Coordination of Ra- or Sa-DABN affords the enantiomeric complexes cis-λ-[PtCl2(Ra-DABN)] (λ,Ra-1) and cis-δ-[PtCl2(Sa-DABN)] (δ,Sa-1), respectively, with no evidence for mismatched diastereomers. X-ray crystallography shows that axial ligand chirality is translated into a configurationally locked λ or δ pucker of the seven-membered metallacycle. NMR spectroscopy supports retention of the structure in CD3CN, whereas kinetic studies in DMSO-d6 reveal pseudo-first-order DABN displacement by solvent. The enantiomeric complexes display intense mirror-image CD spectra, highlighting DABN as an effective axial chirality source for axial-to-chelate-puckering chirality transfer.