Collect. Czech. Chem. Commun. 1985, 50, 1582-1587

Stereochemical changes accompanying acid decarboxylation of the Λ-[Co((S)-valinato)2CO3]- isomers

František Jursík, Jana Ondráčková and Bohumil Hájek

Department of Inorganic Chemistry, Prague Institute of Chemical Technology, 166 28 Prague 6


Λ-trans(O)-[Co((S)-Val)2CO3]- (Val = valine) reacts with 1M-HNO3) (3 min, 28 °C) to form 90% trans(O) and 10% cis(N)-[Co((S)-Val)2(H2O)2]+. Addition of solid KHCO3 to the reaction mixture containing diaquo species gives 96% (95% Λ) trans(O)- and 4% (56% Λ) C1-cis(N)-[Co((S)-Val)2CO3]- isomers indicating decarboxylation of trans(O) isomer proceeds without change in configuration. Acid decarboxylation of Λ-C1-cis(N)-[Co((S)-Val)2CO3]- leads to the mixture consisting from 65% of cis(N)- and 35% of trans(O)-[Co((S)-Val)2(H2O)2]+. When this reaction mixture is treated with solid KHCO, 61% (92% Λ) of C1-cis(N)- and 39% (95% Λ) of -trans(O)-[Co((S)-Val)2CO3]- isomers are formed. Results show that stereochemistry of acid decarboxylation products depends on the starting isomer geometry suggesting steric and electronic factors contribute to isomer proportions.