Wyniki wyszukiwania - BazTech

1

Zastosowanie RP-HPLC z detekcją elektrochemiczną do analizy kompleksów niklu z zasadami Schiffa

Kiersztyn I., Siłak A., Piszcz P., Lamert A., Kurzak K., Kubiak M. S., Głód B. K.

Camera Separatoria

|

2010

|

Vol. 2, (monographs No. 122)

101--107

PL

Kompleksy metali z zasadami Schiffa znane są od końca XIX wieku. Związki te wzbudzają zainteresowanie ze względu na obecność ugrupowania iminowego RCH=NR’ w chemii koordynacyjnej oraz w badaniach procesów metabolicznych zachodzących w organizmach żywych. Zasady Schiffa tworzą z metalami grup przejściowych kompleksy o różnej strukturze, stabilizując różne stopnie utleniania tychże metali. W pracy przedyskutowano rozdział kompleksów niklu (II) z pięcioma ligandami, zasadami Schiffa. Zostały one rozdzielone w układzie faz odwróconych. Z danych literaturowych wiadomo, że zarówno jon centralny jak i ligandy badanych kompleksów ulegają reakcji utleniania i redukcji. Okazało się jednakże, że w niektórych przypadkach detektor elektrochemiczny charakteryzował się dużą niepewnością pomiaru i/lub małą czułością. Elektrochemiczne własności kompleksów zbadano za pomoc woltamperometrii cyklicznej. Okazało się, że niektóre z nich adsorbowały się na elektrodzie i/lub tworzyły przewodzące polimery na powierzchni elektrody, w rozpuszczalnikach o niskiej liczbie donorowej.

2

Ligand-Field Analysis of Low-Spin N,N'-Propylenebis(naphthyldiiminate)nickel(II) in Ethanol Solution

Kurzak K., Gonciarz A., Kuźniarska-Biernacka I.

Polish Journal of Chemistry

|

2005

|

Vol. 79 / nr 1

47-56

EN

Titled complex denoted as [Ni(nappn)]ź0.5H2O, where H2nappn is tetradentate Schiff base: 1,3-bis(naphthylideneimine)propane, has been characterized by elemental analysis, molar conductivity, ultraviolet (UV) and visible (Vis) spectroscopy. The known X-ray structure of this complex shows that Ni atom adopts square-planar coordination. Combined multi-technique experiments have been applied to establish the structure of complex in solution. The molar conductivity value indicates non-electrolytic properties of solution studied. The spectroscopic measurements were used to study the coordination properties of donor-atoms and their bonding abilities. All the experimental transition energies are derived from Gaussian analysis of the solution spectrum. The d-d transition energies were used to derive the angular overlap model (AOM) and crystal-field model (CFM) parameters for the studied complex inD4h symmetry. The first full ligand-field interpretation of the low-spin Schiff base nickel(II) complex in solution has been presented.

3

Spectrochemical Properties of Noncubic Transition Metal complexes in Solutions. XVI. Angular Overlap Treatments of cis-Bis(2,2'-bipyridyl)oxalatechromium(III) Iodide in Aqueous Solution

Kurzak K., Biernacki K.

Polish Journal of Chemistry

|

2004

|

Vol. 78 / nr 5

673-679

EN

The electronic absorption spectrum of cis-[Cr(ox)(bpy)2]I (bpy = 2,2_-bipyridyl; ox = oxalate ion) of aqueous (H2O) solution, has been measured at room temperature and interpreted using the angular overlap model (AOM), and assuming C2v as the effective symmetry. All the experimental transitions are derived from Gaussian analysis of the solution spectrum. The calculations of the ligand field parameters take into account all the transitions, which are required from the ligand field theory (except those energetically higher than the range of the measured spectrum). The coordination

4

Spectrochemical properties of Noncubic transition Metal Complexes in Solutions. XVII. Angular Overlap Treatment of cis-Bis(2,2'-bipyridyl)malonatechromium(III) Iodide in Aqueous Solution

Kurzak K., Biernacki K.

Polish Journal of Chemistry

|

2004

|

Vol. 78 / nr 5

681-686

EN

Amixed ligands chromium(III) complex with bidentate ligands: 2,2_-bipyridyl (bpy) and malonic acid deprotonated (mal-, malonate ion), has been synthesized, investigated and characterized structurally and spectroscopically. Electronic spectra of this complex were recorded in an aqueous solution at room temperature. The 'poor' experimental contours were resolved into the component bands by Gaussian analysis. The spectra were interpreted using C2v symmetry. The resolved spectra have been treated using an angular overlap model (AOM). The effect of _- and _-bonding of the bidentate ligands upon the chromium(III) ion in aqueous solution was described and discussed.

5

Spectrochemical Properties of Noncubic Transition Metal Complexes in Solutions. XIII. Angular Overlap Treatment of Diaquabis(salicylideneaminothiazole)cobalt(II)

Kuźniarska-Biernacka I., Kurzak K.

Polish Journal of Chemistry

|

2003

|

Vol. 77 / nr 1

13-19

EN

Mixed ligand cobalt(II) complex with monodentate (water) and bidentate (Schiff base: salicylidene-2-aminothiazole) ligands has been characterized by elemental analyses, molar conductivities, ultraviolet (UV) and visible (VIS) spectroscopy. The electronic spectra of solids as well as solutions exhibit pseudo-octahedral coordination geometry for the cobalt centre. The molar conductivities indicate their non-electrolytic properties in solvents studied. Combined multi-technique experiments have been used to postulate theC2h geometry for the species in solutions and to determine the coordination properties of ligators and their bonding abilities (ligand-field parameters).

6

Angular Overlap Treatment of cis-Dichlorobis(1,10-phenanthroline)chromium(III) Chloride Dihydrate in Aqueous Solution

Kurzak K., Biernacki K.

Polish Journal of Chemistry

|

2002

|

Vol. 76 / nr 4

503-509

EN

Low-symmetry mixed-ligands cis-[CrCl2(phen)2]Cl complex (phen = 1,10-phenanthroline) has been characterized spectroscopically. Electronic spectrum of aqueous solution of this complex has been measured at room temperature and interpreted using the angular overlap model (AOM), and assuming C2v symmetry. All the experimental transition energies are derived from Gaussian analysis of the solution spectrum. The calculations of the ligand-field parameters take into account all the transitions, which are required in the ligand-field theory (except those energetically higher than the range of the measured spectrum).

7

Z badań nad spektroskopią UV-VIS kompleksów metali przejściowych z zasadami Schiffa w roztworach

Kurzak K., Kuźniarska-Biernacka I.

Wiadomości Chemiczne

|

2001

|

[Z] 55, 9-10

913--931

EN

Metal complexes derived from Schiff bases have been known for one hundred years. The complexes have occupied a central role in the development of coordination chemistry. This situation is manifested by huge number of publications ranging from the physicochemical to biochemical relevant studies of these complexes. The reason for this sustained interest in those compounds are undoubtedly many but important among them must be their general ease to preparation, and diverse properties, e.g., their ability to reversibly bind oxygen, catalytic activity, photochromic and thermochromic properties. Schiff base are those compound containing the azomethine group (-RHC=N-) and usually formed by the condensation of amine with carbonyl compound. Bases which are effective as coordinating ligands bear a functional group, usually -OH, sufficiently near the site of condensation that a five- or six membered chelate ring can be formed upon reaction with a metal ion. Tautomeric equilibrium of three tautomers is possible for Schiff base compounds: imine, enamine and keto-imine. The presence of the imine and enamine tautomeric forms depends on the formation of intramolecular hydrogen bond. It is claimed that enamine form is dominant in napthaldimines while imine form in salicylaldimines. The distribution of the tautomeric equilibrium is strongly depend on the solvents. The presence of keto-imine form is insignificant for Schiff base compounds, but is found in the case of b-diketones and arylimines of b-ketoethers. The most significant complexes of the salicylaldimines are of the types: bi-, tri- and tetracoordinateSchemat 3. The geometry of Schiff base complexes depends on substituent at the coordinating nitrogen atoms. For tetra-coordinate copper(II) complexes different types of geometry is possible. A planar structure has been established for the copper(II) complexes (with bidentate Schiff base) where the substituent is hydrogen atom, hydroxyl, methyl, n-butyl or n-amyl group. In the other hand the copper(II) complexes where the substituent is isopropyl or tert-butyl are pseudo-tetrahedral. For tetra-coordinate cobalt(II), either a square-planar or pseudo-tetrahedral geometry is possible. A pseudo-tetrahedral structure has been established for the cobalt(II) complexes (with bidentate Schiff base) where the substituent is n-propyl, isopropyl, n-butyl, tert-butyl, cyclohexyl or aryl group. Cobalt(II) complexes with bidentate Schiff bases where the substituent is hydrogen atom or hydroxyl group have a planar geometry, because of formation hydrogen bonding between hydrogen (from hydroxyl group) and oxygen (from aldehyde linkage). Geometry of this type is characteristic for cobalt(II) complexes witch Schiff base tetradentate (e.g., with salicylidene-ethylenediamine). The aim of this account is to summarize the result of studies of structural and spectroscopic properties on Schiff bases and their complexes. These have been reviewed based on 104 articles.

8

Spectrochemical Properties of Noncubic Transition Metal Complexes in Solution : XI. Angular Overlap Studies of Bis(oxalato)- and Bis(malonato)diaquachromate(III) Complexes in Aqueous Solution

Kurzak K.

Polish Journal of Chemistry

|

2000

|

Vol. 74, nr 3

331-347

EN

Mixed ligands chromium(III) complexes with monodentate(water) and bidentate ligands: oxalic acid deprotonated or malonic acid have been synthesized, investigated and characterized structurally and spectroscopically. Their geometrical isomers have been studied spectrophotometrically in aqueous solution. The "poor" experimental contours were resolved into the component bands by Gaussian analysis.The effect of different bonding of the bidentate ligands upon the chromium(III) ion in aqueous solution was described and discussed.

9

Angular overlap treatment of cis-bis(2,2'-bipyridyl)dichlorochromium(III) chloride dihydrate in aqueous solution

Kurzak K., Biernacki K.

Polish Journal of Chemistry

|

1998

|

Vol. 72, nr 4

660-666

EN

Six-coordinate cis-[CrCL2(bipy)2](+) complex (bipy=2,2'-bipyridyl) has been prepared. Electron spectrum of aqueous solution of this complex has been recorded and explained by the angular overlap model (AOM), assuming C-2v symmetry. All transition energies are derived from Gaussian analysis of the spectrum. The calculations of the ligand field parameters take into account all the transitions required in the ligand field (LF) theory (except those energetically higher than the range of the spectrum recorded).