Inorganic Asymmetric Synthesis: Asymmetric Synthesis of a Two-Bladed Propeller, Octahedral Metal Complex

A C2 hexadentate, in which two pyridine-2-aldehyde 2‘-pyridylhydrazone (PAPHY) groups are linked to a chiral
auxiliary derived from (R,R)-tartaric acid, (R,R)-1, reacts with iron(II) benzenesulfonate to give the two-bladed propeller,
octahedral complex (PFe)-[Fe{(R,R)-1}](PhSO3)2 with complete diastereoselectivity, as determined by 1H NMR
spectroscopy and X-ray crystallography. Saponification of the ester linkages and deprotonation of the hydrazone-NH groups in the configurationally pure diastereomer affords the complex (PFe)-[Fe(5-HOCH2PAPY)2] with 85%
retention of configuration at the iron stereocenter, as determined by reprotonation of the neutral complex with
enantiomerically pure (aR)-binaphthyl phosphoric acid and analysis of the 1H NMR spectrum of the mixture of
diastereomeric salts produced. This is the first asymmetric synthesis of a two-bladed propeller, octahedral metal
complex by the classical organic methodology of chiral auxiliary-directed, asymmetric synthesis.