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Three geometrical isomers of fac(ida)-[Co(NO2)(gly)(ida)]-have been prepared and optically resolved (gly=glycinato(1–) and ida=iminodiacetato(2–) ligand), and their configurations were determined from the visible and ultraviolet absorption, and circular dichroism spectra. A diastereomeric pair was obtained for the corresponding l-alaninato, l-serinato, or l-prolinato complex.

Two geometrical isomeric pairs of [CrF2(O–O)2]3−and either one of two possible geometrical isomers of [CrF2-(O–O)(en)]−, where O–O denotes oxalate and malonate anions, were newly prepared and characterized by means of the spectral and chromatographic elution behaviors. It was found that [CrF2(ox)(en)]−and [CrF2(mal)(en)]−obtained take cisand transforms, respectively. The ligand field absorption spectra of the present complexes were compared with one another, and with those of the corresponding aqua complexes of the same type. On the basis of the analyses of the absorption spectra in terms of the angular overlap model, the AOM parameters (eσand ex) for the ligands concerned were estimated, and their transferability assumption and the anisotropic π interactions of Cr–O bonding with respect to the chelate plane of the dicarboxylate ligands were discussed.

Elucidation was made for Shimura’s recently proposed reduction parameter, which enables us to improve the prediction of the first absorption band components from Yamatera’s rule, in terms of the angular overlap model(AOM) parameterization for cobalt(III) and chromium(III) mixed ligand complexes. From the configuration interaction between the degenerate components and in view of the empirical relation for the eσaand eσbAOM parameters as revealed recently in the nondegenerate component of trans-[Cra4b2] type complexes, Shimura’s empirical reduction parameter α was elucidated semiquantitatively in relation with the difference between the eσparameter values for the a and b ligands, Δ′σb=3(eσb−eσa); the larger the Δ′σbthe smaller the reduction parameter α, and vice versa.

Potassium (2S,4S)-2,4-pentanediaminetetraacetatochromate(III) monohydrate was newly prepared and was found to be formed stereospecifically with a Λ(ΛΔΛ) absolute configuration as has been revealed for the corresponding Co(III) complex. The circular dichroism spectra in the spin-forbidden transitions of this new complex along with the known analogues, (−)589-ethylenediamine-N,N′-diacetato-N,N′-dipropionatochromate(III) and (+)589-(S,S)-2,2′-(ethylenediimino)disuccinatochromate(III) complexes, were measured and discussed in comparison with those in the first spin-allowed transitions on the basis of the theoretical relations between the rotational strengths for the spin-forbidden and the spin-allowed transitions in trigonal and tetragonal fields.

Two geometrical isomers, cisand trans, of [Cr(CN)2(en)2]+were prepared and the cisisomer was resolved into optical isomers. The ligand field absorption and circular dichroism spectra were discussed and the absolute configuration of cis-(+)546-[Cr(CN)2(en)2]+was determined to Λon the basis of the circular dichroism sign in the first spin-allowed d-d band region.

The circular dichroism (CD) spectra of optically active dinitritobis(diamine)chromium(III) complexes were measured in the visible and near-ultraviolet region, where the diamines used were ethylenediamine, trimethylenediamine, (R)-propylenediamine, (1R, 2R)-1,2-cyclohexanediamine, (2R, 4R)- and (2R, 4S)-2,4-pentanedianiine. The stereochemistry and the conformational (rotational) isomerism of coordinated nitrito ligands were discussed on the basis of the solvent-dependent CD spectra in the near-ultraviolet region of an intraligand absorption band localized on nitrito ligands. It is proposed that the CD variation in the intraligand transition region among the complexes concerned is responsible for the chiral arrangement of nitrito ligands. Further, the conformation of trimethylenediamine chelate in the trans-dinitrito-(R)-propylenediamine complex is determined to take a chair form in comparison with the CD behavior of the corresponding (2R, 4S)-2,4-pentanediainine complex.

The ligand field absorption and circular dichroism (CD) spectra were examined not only for trans-difluoro bis(diamine)chromium(III) complexes with two identical chiral diamines but also for nine new mixed diamine complexes of the same type with different diamines, which were ethylenediamine, trimethylenediamine, (R)- and (S)-propylenediamine, (1R, 2R)-1,2-cyclohexanediamine, (2R, 4R)- and (2R, 4R)-2,4-pentanediamine. The additivity of the CD contributions from the individual chiral diamines were substantiated for most of these complexes. On this basis, the conformational and the vicinal CD contribution due to puckered diamine rings and asymmetric carbon atoms, respectively, were differentiated, and the CD origins of all the present complexes were discussed in connection with stereochemistry.

The crystal structure of the title compound has been determined from the X-ray diffraction data. This complex crystallizes in the monoclinic space group with unit-cell parameters of a=17.724(2), b=8.084(1), c=14.025(2) Å, β=95.06(1)°, and Z=4, and with a space group of P2⁄c. The structure converged to R=0.043 for 2898 reflections. In the complex anion, the chromium is coordinated by the sexadentate cydta ligand, producing a distorted octahedral CrN2O4geometry. The glycinate chelates of the in-plane G(girdling) rings in the CrN2O2plane are more distorted with respect to the Cr–O bond lengths and internal bond angles than are those of the out-of-plane R(relaxed) rings in the CrNO3plane. This may be responsible for the lability to dissociation of the G-ring acetate chelates. A close proximity of non-bonded hydrogen atoms (ca. 1.90 Å) is found between the methylene groups in the R ring and the cyclohexane ring. There are two nonequivalent sodium ions in the unit cell, which link the cydta complex anions to form an anion layer along the c axis.

Three (amino acidato)bis(ethylenediamine)chromium(III) complexes were prepared and resolved into their optically active isomers, their absorption and circular dichroism spectra being measured in the spin-forbidden and spin-allowed d-d transition regions. The amino acids used were glycine, l-alanine, and l-phenylalanine, the latter two yielding pairs of diastereomeric, not enantiomeric, isomers in their complexes. The configurational and vicinal CD curves were obtained from the observed CD of each pair of diastereomers. The additivity of configurational and vicinal contributions to the optical activity in the whole region of the d-d transitions was substantiated. The configurational and vicinal CD peaks in the spin-forbidden band region were assigned in connection with those in the first spin-allowed band region.

Nine chromium(III) complexes of trans-[CrX2(N)4] type with three kinds of optically active diamines (R-propylenediamine, S,S-stilbenediamine and S,S-2,4-pentanediamine) were prepared and the absorption and circular dichroism spectra were measured in the region of their d–d transitions. The CD behaviors in the spinallowed transitions were discussed in comparison with the corresponding cobalt(III) complexes and their bands were assigned to the tetragonal components. On the basis of the theoretical correlation between the rotational strengths for the spin-forbidden transitions and for the spin-allowed transitions, the CD peaks in the spin-forbidden transitions were discussed and assigned.

The absorption and circular dichroism (CD) spectra of twelve optically active chromium (III) complexes containing three bidentate ligands have been measured in the near-infrared to ultraviolet region. CD spectra in the spin-forbidden d-dabsorption band region have been considered mainly in relation to the CD bands in the first spin-allowed d-dabsorption band region. It has been concluded that the absolute configurations of chromium (III) complexes can be determined on the basis of the signs of the CD bands in the spin-forbidden band region. The splitting components of the CD bands in the spin-forbidden band region have been discussed considering the crystal field treatment by Macfarlane.

Two novel mixed chromium (III) complexes containing l-tartrates and 2,2′-dipyridyl or 1,10-phenanthroline have been prepared, and their electronic absorption and circular dichroism spectra and the rotatory dispersion have been measured in the region of near-infrared to ultraviolet. From the construction of molecular models and from the comparison of the CD bands of the present complexes with those of the resolved oxalato complexes, (−)546-K[Cr(ox)2(dip)]·3H2O and (−)546-K[Cr(ox)2(phen)]·4H2O, it has been concluded that the present complexes have a binuclear structure in which two Cr(III) ions are bridged by two tetradentate l-tartrato ligands and that the absolute configuration of the binuclear complexes is Λ(C2)-Λ(C2). Their formation is completely stereospecific and their formulae are represented by Ba[Cr2(l-tart2H)(dip)2]2·9H2O and NH4[Cr2(l-tart2H)(phen)2]·6.5H2O. The absolute configurations of several complexes which commonly belong to a general type, cis-[Cr(O)4(N)2] have been determined on the basis of circular dichroism studies of the present binuclear complexes. The circular dichroism in the spin-forbidden absorption band region have also been measured and discussed.

An optically active complex, [(S)-benzoin-a-oxime]dichlorocopper(II), was prepared and its absorption and circular dichroism spectra were investigated in organic solvents.