Kozo Igi

CIRCULAR DICHROISM STUDIES OF COBALT(III) COMPLEXES OF THE TYPE CIS-[CoN2O4]

Abstract The complex ion [Co(mal)2(tn)]- (mal =malonate ion) and the corresponding complexes of trimethylenediamine (tn) containing the bidentate O-donor ligands C2O4 2- and acetylacetonate (acac) ions were prepared and resolved. Their circular dichroism (CD) spectra are compared with the data reported here for [Co(C2O4)2(I-chxn)]−, [Co(mal)2 (I-chxn)]−, [Co(mal)2(I-pn)]−, and [Co(acac)2(I-pn)]+ complex ions. The malonate complexes reveal greater splitting within the first absorption band region compared to C2O4 2- and acac, but lower net rotational strengths. The contributions to the CD spectra for the optically active ligands are comparable to those reported for other complexes. There is a much greater contribution from the optically active ligand in trans-cyclohexanediaminetetraacetatocobaltate ion than in the corresponding complex of 1,2-propanediaminetetracetatocobaltate ion.

Carbon-13 Nuclear Magnetic Resonance Spectra Geometrical Isomers of Cobalt(III) Complexes with Diethylenetriamine and Iminodiacetate Ion

Abstract Carbon-13 nmr spectra are reported for s-facial, uns-facial, and meridonial isomers of [Co(dien)3]CI3 and [Co(dien)(IDA)] CI, and the s-fac and uns-fac isomers of K[Co(IDA)2]. The nmr peaks are assigned, the spectra clearly reflecting the symmetry of the individual isomers.

CIRCULAR DICHROISM OF COBALT(III) COMPLEXES OF THE TYPE[Co(N)6] CONTAINING BIGUANIDE, AND 2,2′-DIPYRIDYL OR 1,10-PHENANTHROLINE

Abstract Biguanide-diamine mixed complexes of the type [Co(diamine)(Hbg)2]3 and [Co(diamine)2 (Hbg)]3+, where the diamines are 1,10-phenanthroline or 2,2′-dipyridyl, have been prepared and resolved. The absorption and circular dichroism (CD) spectra in water, 0.1 M NaOH aqueous solution, and ethanol are reported. Hydroxide ion affects the CD intensity mainly in the first absorption band region. A marked solvent effect of ethanol was also observed for both absorption and CD spectra especially in the first absorption band region. The absolute configurations for all of these complexes are assigned on the basis of their CD spectra.