Isomerization and racemization of (acetylacetonato)bis(4,4 '-dimethyl-2,2 '-bipyridine 1,1 '-dioxide)chromium(III), (acetylacetonato)bis(4,4 '-dimethoxy-2,2 '-bipyridine 1,1 '-dioxide)chromium(III) and (acetylacetonato)bis(4,4 '-diethoxy-2,2 '-bipyri

摘要

A series of chromium(III) complexes, [Cr(acetylacetonato) (4,4'-X(2)bpdo)(2)](2+) (X=Me, MeO, EtO), where 4,4'-X(2)bpdo denotes 4,4'- substituted 2,2'-bipyridine 1,1'-dioxide, were prepared and resolved into pairs of enantiomers. The perchlorates of these complexes were found to crystallize in a lel(2)(Delta(lambda lambda),Lambda(delta delta)) form; they isomerize to a lelob(Delta(delta lambda),Lambda(delta lambda)) form in water, accompanied by rapid changes in the absorption spectra, and then racemize slowly. The rates of both isomerization and racemization are reduced with an increase in the electron-releasing ability of the 4,4'-X-2 substituent. (C) 1998 Elsevier Science S.A. All rights reserved. [References: 11]