Optically active bis(aminophenols) and their metal complexes.

Abstract

Optically active C2-symmetric bis(aminophenols) based on (R)-2,2'-diaminobinaphthyl (BiniqH4) and (R,R)-2,3-butanediyldianthranilate (BdanH4) have been prepared by condensation of the diamines with 3,5-di-tert-butylcatechol. Group 10 bis(iminosemiquinone) complexes (R)-(Biniq)M (M = Pd, Pt) and (C,R,R)-(Bdan)Pd have been prepared by oxidatively metalating the corresponding ligands. In (R)-(Biniq)M, the C2 axis passes through the approximate square plane of the bis(iminosemiquinone)metal core, while in (C,R,R)-(Bdan)Pd the C2 axis is perpendicular to this plane. In the latter compound, the (R,R)-butanediyl strap binds selectively over one enantioface of the metal complex in a conformation where the methyl groups are anti to one another. Osmium oxo complexes with the intrinsically chiral OsO(amidophenoxide)2 chromophore are obtained by metalation of OsO(OCH2CH2O)2 with (R,R)-BdanH4. Both the (A,R,R) and (C,R,R) diastereomers can be observed, with metalation in refluxing toluene selectively giving the latter isomer. The electronic structures of the complexes are illuminated by the circular dichroism spectra, in conjuction with the optical spectra and TDDFT calculations.