Hayami Yoneda

The crystal and molecular structures of lithium trimethylenediaminetetraacetatoferrate(III) trihydrate Li[Fe(trdta)]·3H2O and sodium ethylenediamine-N,N′-diacetato-N,N′-di-3-propionatoferrate(II) pentahydrate Na[Fe(eddda)]·5H2O

The crystal structures of Li[Fe(trtda)]·3H 2 O and Na[Fe(eddda)]·5H 2 O (trtda = trimethylenediaminetetraacetate and eddda = ethylenediamine- N,N′ -diacetate- N,N′ -di-3-propionate) have been determined by single crystal X-ray diffraction techniques. The former crystal was monoclinic with the space group P 2 1 / n , a = 17.775(3), b = 10.261(1), c = 8.883(2)A, β = 95.86(4)° and Z = 4. The latter was also monoclinic with the space group P 2 1 / n , a = 6.894(2), b = 20.710(6), c = 13.966(3)A, β = 101.44(2)° and Z = 4. Both complex anions were found to adopt an octahedral six-coordinated structure with all of six ligand atoms of trdta 4− or eddda 4− coordinated to the Fe(III) ion, unlike the corresponding edta 4− complex which is usually seven-coordinate with the seventh coordination site occupied by H 2 O. Of the three geometrical isomers possible for the eddda complex, the trans (O 5 ) isomer was actually found in the latter crystal. Factors determining the structural types of metal–edta complexes are discussed in detail.

Chromatographic study of optical resolution : II. Separation of optically active cobalt(III) complexes using potassium antimony d-tartrate as eluent☆☆☆

Abstract Chromatographic separations of the optical isomers of cobalt(III) complexes, [Co(en) 3 ] 3+ , cis -α-[Co(trien)(en)] 3+ , cis -β-[Co(trien)(en)] 3+ , u- fac -[Co(dien) 2 ] 3+ , s- fac -[Co(dien) 2 ] 3+ and mer -[Co(dien) 2 ] 3+ (en = ethylenediamine, trien = triethylenetetramine and dien = diethylenetriamine; u = unsymmetrical; s = symmetrical) have been examined with potassium antimony d -tartrate as eluent, and adjusted retention volumes, separation factors and induced circular dichroism spectra have been determined. Based on these data, a key and lock type association model has been proposed for discrimination between Λ and Δ enantiomers.

Stereochemical Aspects of Optical Resolution of Octahedral Metal Chelates by Liquid Chromatography

Abstract Discrimination of enantiomers of octahedral metal complexes should be done in a mechanism different from that of organic compounds having a tetrahedral asymmetric center. In this respect, the elucidation of the mechanism of optical resolution by chromatography has been one of the most fascinating subjects in coordination chemistry. Since metal complexes usually exist as ions, they are charged on ion-exchange resin and eluted into enantiomers with the eluent containing suitable chiralions(reso1ving agent). While so many chiral metal complexes can be resolved into enantiomers by way of diastereomeric crystals, comparatively few examples of complete resolution by chromatographic techniques have been reported. This is because there are only two resolving agents, d-tartrate and antimony d-tartrate, which are conveniently used for chromatographic separation(1). Here I will describe the outline of works which were done in my laboratory to clarify the mechanism of chromatographic resolution of metal chel...

The crystal structure of the spontaneously resolved Λ(R,R)Δ(G,R)-aquo(ethylenediaminetriacetatoacetic acid) cobalt(III) trihydrate, Λ(R,R)Δ(G,R)-[Co(Hedta)H2O]·3H2O ☆

Abstract Aquo(ethylenediaminetriacetatoacetic acid)cobalt(III) [Co(Hedta)H2O], prepared from an acidic solution (pH

Chromatographic study of optical resolution

A systematic study was made of the chromatographic separation of enantiomers of a series of fac-[Co(β-ala)n(α-ala)3−n] through an anion-exchange column adsorbing chiral and achiral anions such as d-tartrate, antimony d-tartrate, chloride and sulphate. It was found that both the retention volume and the separation factor of the enantiomeric pair increase with increasing number of β-ala ligands when eluted through the d-tartrate form of the resin. On the other hand, when eluted through the antimony d-tartrate form of the resin, the trend of the retention volumes and the separation factors is the reverse of that for the d-tartrate form. These results are discussed in comparison with the results obtained for the corresponding series of fac-[Co(β-ala)n(gly)3−n].

Chromatographic study of optical resolution : III. Separation of isomers of facial tris(aminoacidato)cobalt(III) complexes with d-tartrate and antimony d-tartrate solutions

Abstract A systematic study was made of the chromatographic separation of a series of diastereomeric and enantiomeric pairs of facial tris(aminoacidato)cobalt(III) chelates of formula [Co( l - or d -ser) 3− n (β-ala) n ] and [Co(gly) 3− n (β-ala) n ] (ser - serinato anion, β-ala = β-alaninato anion and gly = glycinato anion) using aqueous solutions of sodium d -tartrate and sodium antimony d -tartrate (abbreviated to Na 2 d -tart and Na 2 [Sb 2 ( d -tart) 2 ], respectively) as eluents. From the data, the separation factors of enatiomeric pairs were calculated for Δ-[C( ol -ser) 3 ] and Λ-[Co( d -ser) 3 0, Λ-[Co( d -ser) 3 ] and Λ-[Co( l -ser) 3 ], Δ-[Co( l -ser) 2 (β-ala)] and Λ-[Co( d -ser) 3 (β-ala)], etc. As a result, it was found that the separation factors of these enantiomeric pairs increase with increasing number of β-ala − ligands when they are eluted with aqueous Na 2 d -tart solution. In contrast to this trend, the separation factors decrease with increase in the number of β-ala − ligands when they are eluted with Na 2 [Sb 2 ( d -tart) 2 ] solution. These trends are discussed in relation to stereochemical association models.

Chromatographic study of optical resolution : V. Resolution of cis-diazidobis(ethylenediamine) and cis-α-diazido (triethylenetetramine) cobalt(III) complexes by antimony d-tartrate

Abstract Among several cis -[CoX 2 (en) 2 ] + and cis -α-[CoX 2 trien] + (X = NCS − , No 2 − and N 3 − ) complexes, only cis -diazido complexes were found to be well resolved into enantiomers by ion-exchange chromatography using K 2 (Sb d -tart) 2 aqueous solution as eluent, and a mechanism involving the ion (Sb d -tart) 2 2- is proposed. Study of the chromatographic behaviour of cis - and trans -[Co(N 3 ) 2 (en) 2 ] + has revealed that whereas the separation factor of geometric isomers decreases with increasing concentration of the resolving agent, the separation factor of optical isomers increases.

A transition-metal diaminophosphonate complex: synthesis and structure of [(η5-C5H5)(CO)2FeP(O)(NEt2)2]2FeCl2

Abstract (η 5 -C 5 H 5 )(CO) 2 FeCl reacts with P(OMe)(NEt 2 ) 2 in benzene to give isolable [(η 5 -C 5 H 5 )(CO) 2 FeP(OMe)(NEt 2 ) 2 ]Cl, which is converted by thermolysis into (η 5 -C 5 H 5 )(CO) 2 FeP(O)(NEt 2 ) 2 FeCl 2 , crystallizing in the monoclinic space group C 2 with a 18.700(4), b 9.065(1), c 16.608(3) A β 135.54(1)°, and Z = 4. X-Ray diffraction has revealed that the P(O)(NEt 2 ) 2 group covalently bonds to the iron atom of the (η 5 -C 5 H 5 )(CO) 2 Fe moiety through the P atom and also coordinates to FeCl 2 through the phosphoryl oxygen, and that one of the nitrogen atoms in the P(O)(NEt 2 ) 2 group has a planar geometry. (η 5 -C 5 H 5 (CO) 2 FeP(O)(NEt 2 ) 2 ] is obtained by treatment with pyridine.

Association constants of Λ- and Δ-tris(ethylenediamine)cobalt (III) with antimony L-tartrate anion

Abstract The ion association constants were determined in aqueous solution for the ion pairs, Λ- and Δ-[Co(en)3]3+ with antimony L-tartrate dianion, by utilizing circular dichhrosim (CD) measurements: KΛ = 46.6 ± 0.7 at 430 nm and 47.3 ± 0.6 at 455 nm for Λ-isomer; KΔ = 25.6 ± 0.9 at 430 nm and 26.8 ± 0.6 at 455 nm for Δ-isomer. It was found that the difference of the association constants for this system is considerably large in comparison with that for the L-tartrate system reported previously and this result is closely related to the chromatographic behaviors of these systems.

Chromatographic Separation of Isomers of Meridional Tris(amino-acidato) Cobalt(III) Homochelates and Their Absolute Configuration

Abstract Chromatographic separation of enantiomers or diastereomers was undertaken for four kinds of meridional [Co(AA)3] complexes through the column packed with antimony d-tartrate form of the anion exchange resin, where AA stands for D-alanine, L-alanine, glycine and β-alanine. From the CD spectra of the separated isomers, it was revealed that the δ-isomer was eluted first for the three α-aminoacidato chelates. As to the case of mer-[Co(β-ala)3] a single crystal X-ray analysis was made for the second eluted isomer and determined its absolute configuration to be Δ. Thus, it was concluded that in all four cases the Δ-isomer has greater affinity toward antimony d-tartrate anion than the δ-isomer. This makes a contrast to the case of the corresponding facial [Co(AA)3] in which the δ-isomer has greater affinity toward antimony d-tartrate than the Δ-isomer. Based on the values of the separation factors for the four enantiomeric pairs, the association mode effective for chiral discrimination was discussed.