Myung-Ki Doh

Copper(II) complexes with novel chiral amidate ligands

Abstract Two new copper(II) complexes, {[Cu2(S-alaamp)2(ClO4)]ClO4}n (1) and [Cu(S-valamp)(H2O)(ClO4)] (2) [where S-alaamp=4(S)-1-(2-pyridyl)-3-oxo-4-amino-2-azapentane, S-valamp=4(S)-1-(2-pyridyl)-3-oxo-4-amino-4,5-dimethyl-2-azahexane] are prepared and characterized. Compound 1 exists as 1-D polymeric chain where an amide oxygen atom is linked to adjacent copper(II) ion, while 2 is a square-pyramid in the solid state. Compounds 1 and 2 are involved in offset π–π stacking interactions via the pyridine groups of the ligands, which give rise to 2-D sheets.

Synthesis and crystal structure of the trans-dichloro(N,N′-bis-[2(S)-pyrrolidylmethyl]-ethane-1,2-diamine)cobalt(III) tetrachlorocobaltate(II) complex

A trans -dichlorot( N , N ′-bis-[2( S )-pyrrolidylmethyl]ethane-1,2-diamine)cobalt(III) tetrachlorobaltate(II) complex was synthesized using trans -[Co III (pyridine) 4 Cl 2 ]Cl, and the crystal structure was determined by X-ray analysis. This structure was also confirmed by optical spectroscopy, including circular dichroism and absorption spectra. The trans -dichloro complex was orthorhorabic, space group P 2 1 2 1 2 1 (No. 19), a = 6.404(1), b = 17.255(4), c = 23 701(2) and Z = 4. The conformations of the in-plane, containing metal and four donor atoms of N , N ′-bis-[2( S )-pyrrolidylmethyl]ethane-1,2-diamine, were δ, λ and δ gauche forms. The four nitrogen donor atoms were stereoselectively directed only to the SRRS coordination. The stereoselectivity in this complex may originate from the stereospecific characteristic of the ligands.

STEREOSELECTIVITY ON ELECTRON TRANSFER REACTIONS(I); REACTION OF THE Λ-[Co(EDDS)]− AND RAC-[Co(DIAMINE)3]2+ COMPLEXES (DIAMINE = EN, CHXN)

Abstract The absolute configuration of an optically active Λ-[Co(EDDS)]− (EDDS = ethylene-diaminedisuccinate) complex was determined as Λ by the regional rule and spectroscopic data. The stereoselective ionic association between Λ-[Co(EDDS)]− and rac-[Co(en)3]3+ occurs preferentially between Λ-[Co(EDDS)]− and δ-[Co(en)3]3+. The stereoselective electron transfer reaction between Λ-[Co(EDDS)]− and rac-[Co(en)3]2+ has been investigated in aqueous solution, DMF and DMSO. Their enantiomeric excesses (e.e.) observed are 14%, 26% and 40% of δ-[Co(en)3]3+, respectively. The electron transfer reaction between Λ-[Co(EDDS)]− and conformationally restricted [Co(chxn)3]2+ has been examined in aqueous and DMSO solution. In aqueous solution, there are four isomers in the product which were determined as lel3, lel2ob, lelob2 , and ob3 of δ-[Co(chxn)3]3+ with optical purities of 22%, 25%, 11% and 10% e.e. respectively. In DMSO, the reaction produces lel3 -δ-and lel2ob-δ-[Co(chxn)3]3+ with optical purities of 100% and 75% ...

STEREOSELECTIVITY OF ELECTRON TRANSFER REACTIONS (II); REACTION OF Λ-[Co(EDDS)]− AND Co(II) COMPLEXES WITH STEREOSPECIFIC DIAMINE LIGANDS

Abstract Stereoselective electron-transfer between optically active Λ-[Co(EDDS)]− and [Co(diamine)3]2+ (diamine = racemic-1,2-diaminopropane (pn); R-1,2-diaminopropane (R-pn)) have been investigated in aqueous and in DMSO solutions. In aqueous solution, the reaction between Λ-[Co(EEDS)]− and [Co(pn)3]2+ produces four conformational isomers of the [Co(pn)3]3+ complex which have the Λ-forms in excess. Their optical purities are increased ob3>lelob2> lel2ob> lel3 . In contrast, the reaction in DMSO results in more δ isomers than Λ and the sequence of optical purities are in reversed order. The reaction between Λ-[Co(EDDS)]− and [Co(R-pn)3]2+ in aqueous solution produces two conformational isomers of [Co(R-pn)3]3+; their absolute configurations are identified as δ-lel2ob and Λ-ob3 . In DMSO, in contrast, the reaction produces only one isomer which is identified as δ-lel2ob.

Synthesis and structure of Cu(II) complex with chiral amidate ligand, 4(S)-1-(2-pyridyl)-3-oxo-4-aza-7-thiaoctane

Abstract A polymeric compound, [Cu(S-metamp)(H2O)(NO3)] (1) [S-metamp (=4(S)-1-(2-pyridyl)-3-oxo-4-aza-7-thiaoctane)] was prepared and characterized by X-ray crystallography. Crystal data for 1 monoclinic, P2 1 , a=7.7799(7) A, b=20.613(2) A, c=9.815(1) A, β=90.287(8), V=1573.9(3) A 3 , Z=4 and R=0.0306. In 1, the coordination geometry around Cu(II) ion is distorted square-pyramidal with an oxygen atom from nitrate at the apex, and three nitrogen atoms from S-metamp and an oxygen from aqua ligand in a plane. The two hydrogen atoms of the coordinated water molecule interact with the oxygen atom of nitrate and amide oxygen atom by hydrogen bonding in the solid state. The combination of this gives a structural feature in a 2D polymeric arrangement.