94404-90-7Relevant academic research and scientific papers
Stereochemistry and relative stability of isomers of trans-dichlorocobalt(III) complexes with chirally substituted 3,7-diazanonane-1,9-diamine
Saburi, Masahiko,Ishii, Youichi,Obata, Shusei,Yamaguchi, Motowo,Yoshikawa, Sadao
, p. 527 - 533 (2008/10/08)
The stereochemistry of trans-dichlorocobalt(III) complexes with chiral derivatives of 3,7-diazanonane-1,9-diamine such as (2S,8S)-2,8-dimethyl-3,7-diazanonane-1,9-diamine (3,9-Me2-2,3,2-tet), (35,11S)-2,12-dimethyl-5,9-diazatridecane-3,11-diamine (2,10-Ip2-2,3,2-tet), and (25,10S)-1,11-diphenyl-4,8-diazaundecane-2,10-diamine (2,10-Bn2-2,3,2-tet) was examined on the basis of 13C NMR and circular dichroism (CD) measurements. The trans-dichloro complexes obtained by treating the corresponding carbonato complexes with hydrochloric acid adopt specifically the RR configuration with respect to the coordinated secondary nitrogen centers. The trans-RR isomers of 3,9-Me2- and 2,10-Ip2-2,3,2-tet isomerized in methanol (63°C) to give rise to equilibrated mixtures of trans-RR and trans-RS isomers. The isomer ratio [RS]/[RR] was estimated as 1.65 ± 0.05 and 2.4 ± 0.4, respectively, for 3,9-Me2- and 2,10-Ip2-2,3,2-tet complexes. The observed influences of position or bulkiness of substituents on the isomer distribution were discussed, taking the steric interactions involved in the RS isomer into consideration. Λ-β-(Oxalato)cobalt(III) complexes with 2,3,2-tet derivatives including (3S,9S)3,9-bis(aminomethyl)-2,10-dimethyl-4,8-diazaundecane (3,9-Ip2-2,3,2-tet) were also prepared to interpret the fact that 3,9-Ip2-2,3,2-tet gave no trans-dichloro complex.
