The complexes, [Co(l-val)(NH3)(tacn)]2+ (tacn=1,4,7-triazacyclononane), [Co(gly)(NH3)(Me-tacn)]2+ (Me-tacn=(2R)-2-methyl-1,4,7-triazacyclononane) have been prepared and separated into diastereomers by column chromatography. Six other complexes, [Co(a)(β-ala)(tacn)]n+ (a=CN−, NO2−, or NH3) and [Co(a)(gly)(tacdd)]n+ (a=NO2−, NCS−, or H2O; tacdd=1,5,9-triazacyclododecane) have also been prepared and resolved into enantiomers. By comparing the CD spectra of the l-valinato and the Me-tacn complexes with that of [Co(gly)(NH3)(tacn)]2+, the optical activities of [Co(a)(gly)(tacn)]+ are considered to be mainly derived from chiral arrangements of four kinds of donor atoms. The change from five-membered chelate ring to a six-membered one has slight influence upon the CD spectral shapes in the β-alaninato complex, but a large influence in the tacdd complexes.
配合物,[Co(1-val)(NH 3 )(tacn)] 2+ (tacn=
1,4,7-三氮杂环壬烷),[Co(gly)(NH 3 )(Me-tacn)] 2+ (Me- tacn=(2R)-
2-甲基-
1,4,7-三氮杂环壬烷)已被制备并通过柱色谱法分离成非对映异构体。其他六种配合物,[Co(a)(β-ala)(tacn)]n+ (a=CN−,
NO2−, or NH3) 和 [Co(a)(gly)(tacdd)]n+ (a= −) 、
NCS− 或
H2O;tacdd=
1,5,9-三氮杂环十二烷)也已被制备并解析为对映体。通过将l-valinato和Me-tacn配合物的CD光谱与[Co(gly)(NH3)(tacn)]2+的CD光谱进行比较,得到[Co(a)(gly)(tacn)]的旋光活性+ 被认为主要源自四种供体原子的手性排列。从五元螯合环到六元螯合环的变化对
β-丙氨酸配合物中的圆二色光谱形状影响很小,但对tacdd配合物影响很大。