• Title/Summary/Keyword: donor atoms

Search Result 82, Processing Time 0.02 seconds

Novel Linking Ligand Containing Sulfur-Donor Atoms and Its Compounds of Palladium and Silver

  • Lee, Hee-K.;Lee, Soon-W.
    • Bulletin of the Korean Chemical Society
    • /
    • v.28 no.3
    • /
    • pp.421-426
    • /
    • 2007
  • A linking ligand containing sulfur donor atoms in the terminal thiophene rings, 1,2-bis(thiophen-2-ylmethylene) hydrazine (L), was prepared by Schiff-base condensation. Ligand L reacted with [PdCl2(NCPh)2] to produce a molecular Pd compound [PdL2Cl2] (1). On the other hand, it reacted with AgNO3 and AgClO4 to produce a 2-D network [AgL0.5(NO3)] (2) and a 1-D polymer [AgL]ClO4 (3), respectively, whose structures are based on secondary intermolecular forces such as H-bonding, van der Waals interaction, and π-π stacking. Polymer 2 exhibited photoluminescence at room temperature in the solid state.

Synthesis and Properties of Polydentate Schiff Base Ligands having $N_nO_2$ (n=3~5) Donor Atoms and Bromine Substituent and their Transition Metal Complexes (여러자리 질소-산소계 시프염기 리간드와 전이금속착물의 합성 및 전기화학적 특성)

  • Kim, Sun-Deuk;Shin, Yun-Yeol;Park, Sung-Woo
    • Analytical Science and Technology
    • /
    • v.11 no.6
    • /
    • pp.440-447
    • /
    • 1998
  • Polydentate Schiff base ligands 5-Br-BSDT(bis(5-bromosalicylaldehyde)diethylenetriamine) having $N_3O_2$ atoms, 5-Br-BSTT(bis(5-bromosalicylaldehyde)triethylenetetramine) having $N_3O_2$ atoms, 5-Br-BSTP(bis(5-bromosalicylaldehyde)tetraethylenepentamine) having $N_3O_2$ atoms were synthesized. Stability constants of the complexes between these ligands and the metal ions such as Cu(II), Ni(II) and Zn(II) were measured in DMSO by a polarographic method. It was observed that all metal(II) ions employed in this study formed 1 : 1 complexes with Schiff base ligands. Stability constants for the ligands were in the order of Cu(II)>Ni(II)>Zn(II), and for complex formation were in the order of 5-Br-BSTP>5-Br-BSTT>5-Br-BSDT according to the increasing in the number of donor atoms. Both enthalpy and entropy changes are obtained in negative valves. Exothermicity for the complex formation indicated tight binding between the ligands and metal ions. The negative entropy change would be related to the fact that solvent molecules are strongly interacting with the metal complexes.

  • PDF

Oxovanadium(IV) Complexes Containing VO(ONS) Basic Core: Synthesis, Structure, and Spectroscopic Properties

  • Jang, Yoon-Jung;Lee, Uk;Koo, Bon-Kweon
    • Bulletin of the Korean Chemical Society
    • /
    • v.26 no.1
    • /
    • pp.72-76
    • /
    • 2005
  • Some mononuclear oxovanadium(IV) complexes having the general formula [VOL(bidentate)] (1-4) of which L is tridentate ONS-donor salicylaldehyde S-methyldithiocarbazate (sal-mdtc$^{2-}$) or salicylaldehyde 4- phenylthiosemicarbazate (sal-phtsc$^{2-}$) and bidentate stands for 2,2'-bipyridyl (bpy) or 1,10-phenanthroline (phen) have been synthesized. The complexes were characterized by elemental analyses, FAB mass, UV, IR spectroscopy, and cyclic voltammetry. Two of the complexes [VO(sal-mdtc)(bpy)] (1) and [VO(sal-mdtc) (phen)] (2) were crystallographically characterized. The structures revealed that vanadium atom is octahedrally coordinated by the O, N, and S donor atoms of the tridentate ligand, the two N atoms of bidentate ligand, and the oxo atom. The oxygen donor, occupying an apical position has a trans-labilizing effect, resulting in elongation of the V-N bond. The cyclic voltammograms of the complexes exhibited one cathodic response in the range −d1.45 $\sim$ −f1.52 V due to the reduction of V(IV) to V(III).

Synthesis and Characterization of Holmium Complexes Containing $\beta$-Diketonate Ligands

  • 이정해;정영숙;손윤수;강성주
    • Bulletin of the Korean Chemical Society
    • /
    • v.19 no.2
    • /
    • pp.231-235
    • /
    • 1998
  • Two holmium β-diketonate complexes, Ho(hfa)3(H2O)2 (1) and [Ho(hfa)3(H2O)2](triglyme) (2), have been prepared and characterized by IR, TGA, and single-crystal X-ray analyses. These complexes show polymeric chains by the intermolecular hydrogen bondings. The donor atoms of the intermolecular hydrogen bonding in both complexes are hydrogen atoms of the coordinated water molecules. The acceptor atoms in 1 are the carbonyl oxygen atoms of β-diketonate ligands whereas those in 2 are oxygen atoms of the triglyme ligand. While compound 1 decomposes cleanly to Ho2O3, compound 2 sublimes intact. Crystal data for 1 and 2 are as follows: Ho(hfa)3(H2O)2 triclinic P1, a=10.158(4), b=11.628(2), c=12.579(6) Å, α=67.02(3)°, β=73.95(4)°, γ=76.12(2)°, V=1299.8(8) Å3. [Ho(hfa)3(H2O)2](triglyme), monoclinic P21/c, a=12.559(3), b=19.111(2), c=16.789(6) Å, β=110.59(4)°, V=3772(2) Å3.

New Tridentate Ligands with Mixed Donor Atoms for Cu-Based Atom Transfer Radical Polymerization

  • Cho, Hong-Youl;Han, Byung-Hui;Kim, Il;Paik, Hyun-Jong
    • Macromolecular Research
    • /
    • v.14 no.5
    • /
    • pp.539-544
    • /
    • 2006
  • 2-Furancarboxaldehyde-2-pyridinylhydrazone (FPH) and 5-methyl-2-furancarboxaldehyde-2-pyridinylhydrazone (MFPH) were synthesized and used as tridentate ligands of copper (I) bromide for the atom transfer radical polymerization of methyl methacrylate (MMA) and styrene. The polymerization of methyl methacrylate achieved high conversion and yielded polymers with a good control of molecular weight and low polydispersity (PDI=1.33). Higher PDI were observed in the polymerization of styrene. Using 1-phenyl ethylbromide (PEBr) and ethyl 2-bromoisobutyrate (EBiB) as model compounds for the polymeric chain ends, the activation rate constants of the new catalytic systems were measured. These results were correlated with the polymerization results and compared with another catalytic system previously reported.

Electrochemical Studies of Oxovanadium(IV) Complex of 2-Amino-1-cyclopentene-1-dithiocarboxylate

  • Young-Jin Kim;Duck-Soo Park;Yoon-Bo Shim;Sung-Nak Choi
    • Bulletin of the Korean Chemical Society
    • /
    • v.11 no.2
    • /
    • pp.89-94
    • /
    • 1990
  • The redox properties of 2-amino-1-cyclopentene-1-dithiocarboxylate anion (acdc) and its oxovanadium complex, $VO(acdc)_2$ have been investigated in dimethylformamide (DMF) with polarography and cyclic voltammetry. Bis(2-amino-1-cyclopentene-1-dithiocarboxylate) oxovanadium(IV) exhibits two polarographic oxidation waves and two reduction waves in the potential range from +0.50V to - 2.4V vs. the Ag/AgCl (DMF) reference electrode. The second oxidation wave appeared at - 0.08V is found to be reversible and is attributed to the formation of $VO(acdc)_2\;^+$. The first reduction process (at - 0.60V) is also reversible and this reduction process is caused by the electrode process of formation of $VO(acdc)_2$-species. The half wave potential for the reduction, V(IV)$\to$V(III) is more positive for oxovanadium complexes containing sulfur donor atoms than other VO(IV) complexes having oxygen or nitrogen donor atoms.

Luminescence, Excitation and Far-infrared Spectroscopy of cis-$\alpha$-Dichlorotriethyleneteraminechromium(III) Chloride

  • 최종하
    • Bulletin of the Korean Chemical Society
    • /
    • v.19 no.5
    • /
    • pp.575-579
    • /
    • 1998
  • The 77 K luminescence and excitation spectra, and 298 K infrared and absorption spectra of $cis-{\Alpha}-[Cr(trien)Cl_2]Cl{\cdot}H_2O$ (trien=triethylenetetramine) have been measured. Ligand field electronic transitions due to spin-allowed and spin-forbidden are assigned. The zero-phonon line in the excitation spectrum splits into two components by $198\; cm^{-1}$, and the large $^2E_g$ splitting can be reproduced by the modern ligand field theory. It is confirmed that nitrogen atoms of the trien ligand have a strong σ-donor character, but chloride ligand has weak σ- and π -donor properties toward chromium(III) ion.

Formation of Cadmium(II) Nitrate Complexes with Macrocycles

  • Ho-Doo Kim;Hak-Jin Jung;Oh-Jin Jung
    • Bulletin of the Korean Chemical Society
    • /
    • v.14 no.5
    • /
    • pp.561-567
    • /
    • 1993
  • The twelve macrocycle (L) complexes of cadmium(II) nitrate have been synthesized: $CdL(NO_3)_2$. All the complexes have been indentified by elemental analysis, electric conductivity measurements, IR and NMR spectroscopic techniques. The molar electric conductivities of the complexes in water and acetonitrile solvent were in the range of 236.8-296.1 $cm^2{\cdot}mol^{-1}{\cdot}ohm^{-1}$ at 25$^{\circ}$C. The characteristic peaks of macrocycles affected from Cd(II) were shifted to lower frequencies as compared with uncomplexed macrocycles. A complex with 1,4,8,11-tetrakis(methylacetato)-1,4,8,11-tetraaza cyclodecane (L4) exhibited two characteristic bands such as strong stretching (1646 $cm^{-1})$, and weaker symmetric stretching band (1384 $cm^{-1})$. NMR studies indicated that all nitrogen donor atoms of macrocycles have greater affinity to cadmium(II) metal ion than do the oxygen atoms. The $^{13}$C-resonance lines of methylene groups neighboring the donor atom such as N and S were shifted to a direction of high magnetic field and the order of chemical shifts were $L_1 < L_2 < L_3 < L_6 < L_4$. Also the chemical shifts values were larger than those of methylene groups bridgeheaded in side-armed groups. This result seems due to not only the strong interaction of Cd(Ⅱ) with nitrogen donors according to the HSAB theory, but weak interaction of Cd(Ⅱ) and COO- ions or sulfur which is enhanced by the flexible methylene spacing group in side-armed groups. Thus, each additional gem-methyl pairs of L_3, L_4\;and\; L_6$ macrocycles relative to $L_1, L_2,\;and\;L_5$ leads to an large enhancement in Cd(II) affinity. ^{13}C$-NMR spectrum of the complex with $L_{12}$ (1,5,9,13-tetracyclothiacyclohexadecane-3,11-diol) reveals the presence of two sets of three resonance lines, and intensities of the each resonance line have the ratio of 1 : 2 : 2. This molecular conformation is predicted as structure of tetragonal complex to be formed by coordinating two sulfur atoms and the other two sulfur atoms which is affected by OH-groups.

Comparison of Photocyclization Reactions of Fluoro- vs Nonfluoro-Substituted Polymethyleneoxy Donor Linked Phthalimides

  • Park, Hea Jung;Ryu, Young Ju;Kim, Kyung Mok;Yoon, Ung Chan;Kim, Eunae;Sohn, Youngku;Cho, Dae Won;Mariano, Patrick S.
    • Bulletin of the Korean Chemical Society
    • /
    • v.34 no.4
    • /
    • pp.1108-1114
    • /
    • 2013
  • Photochemical reactions of fluoro- vs. nonfluoro-substituted polymethylenoxy chain linked phthalimide were carried out to explore how electronegative fluorine atoms inside the donor chain influence photocyclization reaction efficiencies and to briefly determine the alkali metal binding properties of the photoproducts. The results of this study show that the fluorine-substituted donor chain linked phthalimide undergoes inefficient photocyclization via single electron transfer (SET)-induced excited state pathways to generate 14-membered cyclic amidol compared to nonfluoro-analog due to low electron donor ability of the terminal oxygen donor site. These results show that photoinduced intramolecular SET processes arising from ${\alpha}$-silyl ether electron donors to phthalimides are largely dependent on the kinds of substituents inside donor chain. Finally, a preliminary study with the cyclic amidols generated in this effort showed that they have weak alkali metal cation binding properties regardless of absence/presence of fluoro-substituents.