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1

Synthesis and Properties of New Bimetallic Complexes of General Formula: [Cu(diamine)2][Cr(NCS)4(NH3)2]2

Wrzeszcz G., Grzebielucha T.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 9

1575-1582

EN

Four new thiocyanato bridged heteronuclear com plexes of general formula [Cu(diamine)2][Cr(NCS)4(NH3)2]2, where diamine = ethylenediamine (en) (1), 1,2-di -amino propane (pn) (2), 1,3-diaminopropane (tn) (3) and N-methylethylenediamine (men) (4) have been prepared in solid state by treatment of [Cr(NCS)4(NH3)2]– with corresponding cationic [Cu(diamine)2]2+ complex in anaqueous solutions. They have been characterized by elemental and thermal analysis, spectroscopic methods (IR, UV-Vis, EPR), and variable-temperature magnetic susceptibility measurements. The formation of end-to-end thiocyanato bridges between tetragonal (elongated octahedral) Cu(II) and octahedral Cr(III) is evident from IR and electronic spectra. The EPR spectra measured at room temperature on solid samples (1 and 3) show very broad and symmetric signal at g = 2.02 and 2.07, respectively. Magnetic data reveal the absence of significant exchange inter actions between the Cr(III) and Cu(II) ions in all studied complexes (1–4). Thermal decomposition after ammonia release is multistage and yields CuO, and Cr2O3 as final products.

2

Kinetics of Chromium(V) Formation from Some Tetraazamacrocyclic Chromium(III) Complexes in Alkaline Media

Impert O., Katafias A., Kita P., Wrzeszcz G.

Polish Journal of Chemistry

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2008

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Vol. 82, nr 8

1673-1673

3

Kinetics and Mechanism of trans-[Cr(cyca)(OH)F]+Complex Oxidation by [Fe(CN)6]3- Ion in Strongly Alkaline Aqueous Solutions

Katafias A., Impert O., Kita P., Wrzeszcz G., Dominiak D.

Polish Journal of Chemistry

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2006

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Vol. 80, nr 6

931-941

EN

Oxidation of the trans-[Cr(cyca)(OH)F]+ complex, where cyca = meso-5,5,7,12,14- hexamethyl-1,4,8,11-tetraazacyclotetradecane, by [Fe(CN)6]3- ion in strongly alkaline media has been studied. A long-lived intermediate chromium(V) species was detected basing on the EPR signal at giso = 1.986. The hyperfine structure of the main EPR signal is consistent with the d1-electron interactions with four equivalent or nearly equivalent nitrogen nuclei and [CrV=O(cycaox)]3+ formula, where cycaox = oxidized cyca, can be postulated for the intermediate CrV complex. Kinetics of the rate limiting stage - electron transfer from the chromium(III) complex - has been studied in details applying an excess of the reductant and [OH-] at ionic strength equal 2.0 M. The rate law: -d[FeIII] dt = d[CrIV] dt = 0,5k cb K[OH-] 1+ 0,5(K-1)[OH-] [CrIII][FeIII] is consistent with an outer-sphere electron transfer from the conjugate base (cb) of the reductant formed in a preequilibrium (K) step. Reactivity of the deprotonated chromium(III) complex is characterized by kcb 298 = 9.7,deltaH#= (44.1š 0.5) kJ_mol-1, deltaS# = (-78.0 š 2.0) JxK-1xmol-1 and the preequilibrium step -by K298 = 0.237, delta H0 = (11.5 š 1.8) kJ_mol-1, delta S0 = (26.6 š 5.8) JxK-1xmol-1.

4

Ability of 2,4D and 2,4DP Herbicides to Combine with Metal Ionsof Biological Interst (Part 3): Manganese(II) Complexes

Zwolińska A., Ptaszyński B., Wrzeszcz G.

Polish Journal of Chemistry

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2005

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Vol. 79 / nr 10

1585-1595

EN

The synthesis and properties of manganese(II) complexes with the commercial auxin herbicides: 2,4-dichlorophenoxyacetic acid (2,4D; C8H6O3Cl2) and 2-(2,4-dichlorophenoxy)- propionic acid (2,4DP; C9H8O3Cl2) are reported. On the basis of the results of elemental analysis and Mn(II) determination, the following molecular formulae were proposed for the obtained compounds: Mn(C8H5O3Cl2)2.2H2O (Mn-2,4D) and Mn(C9H7O3Cl2)2.2H2O (Mn-2,4DP). X-ray powder analysis was carried out. The water solubility of the synthesized complexes at room temperature was determined. The IR spectra, conductivity data (in methanol and dimethylformamide), variable temperature magnetic susceptibility and the way of Mn-herbicide coordination are discussed. Thermal decomposition of these complexes in air was studied by TG, DTG, DTAand TG/MS methods with simultaneous analysis of the solid and gaseous products of pyrolysis.

5

Ability of 2,4D and 2,4DP Herbicides to Combine with Metal Ions of Biological Interest (Part 1): Copper(II) Complexes

Zwolińska A., Ptaszyński B., Wrzeszcz G.

Polish Journal of Chemistry

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2004

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Vol.78 /nr 11-12

1987-1996

EN

Copper(II) complexes with the commercial auxin herbicides 2,4-dichlorophenoxyacetic acid (2,4D; C8H6O3Cl2) and 2-(2,4-dichlorophenoxy)-propionic acid (2,4DP;C9H8O3Cl2) were prepared and characterized. On the basis of the results of elemental analysis and Cu(II) determination, the following molecular formulae were proposed for the obtained compounds: Cu(C8H5O3Cl2)2.4H2O (Cu-2,4D) and Cu(C9H7O3Cl2)2.H2O (Cu-2,4DP).Water solubility of synthesized complexes at room temperature was determined. The complexes have been characterized by IR, VIS and EPR spectroscopy, conductivity (in methanol and dimethyloformamide), magnetic measurements and X-ray diffraction analysis. Thermal decomposition of these compounds in air was studied by TG, DTG, DTAand TG/MS methods with simultaneous analysis of the solid and gaseous products.

6

Synthesis and Characterization of New Thiocyanato Bridged Heterobimetallic Complexes with the General formula: [Cu(diamine)2]3[Cr(NCS)6]2.nH2O

Wrzeszcz G.

Polish Journal of Chemistry

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2003

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Vol. 77 / nr 7

845-854

EN

Four new thiocyanato bridged heteropolynuclear complexes with general formula [Cu(diamine)2]3[Cr(NCS)6]2_nH2O, where diamine = N-ethylethylenediamine (N-Et-en), N-isopropylethylenediamine (N-Pri-en), N-methyl-1,3-propanediamine (N-Me-tn), 1,3-diaminopentane (C-Et-tn), were prepared by treatment of corresponding cationic [Cu(diamine)2]2+ complex with [Cr(NCS)6]3-in aqueous solutions. Solid products were formulated as [Cu(N-Et-en)2]3[Cr(NCS)6]2, [Cu(N-Pri-en)2]3[Cr(NCS)6]2_2H2O, [Cu(N-Me-tn)2]3[Cr(NCS)6]2_H2O and [Cu(C-Et-tn)2]3[Cr(NCS)6]2_H2O and characterized by spectroscopic methods, magnetic measurements and thermal analysis. The formation of end-to-end thiocyanato bridges between tetragonal Cu(II) and octahedral Cr(III) is evident from IR and electronic spectra. The EPR spectra measured at room temperature on solid samples show broad, symmetric signal at g = 2.01-2.03. Variable-temperature magnetic susceptibility measurements reveal the presence of weak antiferromagnetic interactions in [Cu(N-Pri-en)2]3[Cr(NCS)6]2_2H2O and [Cu(C-Et-tn)2]3[Cr(NCS)6]2_H2O. Thermal decomposition after dehydration is multistage and yields CuO and CuCrO2 as final products.

7

Synthesis and Characterization of New Thiocyanato Bridged Complexes with the General Formula [MLn}3[Cr(NCS)6]2.mH2O, where M=Cu(II), Ni(II), Co(II); L=Various Substituted Imidazoles

Wrzeszcz G., Dobrzańska L., Grodzicki A., Rozpłoch F.

Polish Journal of Chemistry

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2003

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Vol. 77 / nr 2

147-156

EN

New thiocyanato bridged complexes of the type [CuL4]3[Cr(NCS)6]2_mH2O [L = 1-methylimidazole (1-Meim), 2-methylimidazole (2-Meim), 1,2-dimethylimidazole (1,2- Me2im)] and [M(1-Meim)6]n[{M(1-Meim)4Cr(NCS)6}2n]_mH2O (M = Ni(II), Co(II) were prepared by the reaction of [Cr(NCS)6]3- with the appropriate [MLn]2+ complex in an aqueous solution and characterized by elemental and thermal analysis, IR, UV-VIS, EPR and temperature variable magnetic susceptibility. The presence of NCS bridges between M(II)-Cr(III) centres is evident from IR spectra. The electronic spectra correlate with proposal of different composition of Cu3Cr2 and M3Cr2(M = Ni, Co) systems. The parameters determined from temperature dependence on magnetic susceptibility (80-300 K) indicate weak or negligible antiferromagnetic interaction for obtained Cu(II)-Cr(III), Ni(II)-Cr(III) and Co(II)-Cr(III) systems. Thermal decomposition after dehydration is multistage and yields CuO + CuCrO2 and MIIO+MIICr2O4 as final products, respectively.

8

Spectroscopic, Magnetic and Thermal Properties of New Thiocyanato Bridged Complexes of the Type [M(diamine)2]3[Cr(NCS)6]2.nH2O4, where M=Cu(II), Ni(II)

Wrzeszcz G., Dobrzańska L.

Polish Journal of Chemistry

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2003

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Vol. 77 / nr 10

1245-1254

EN

Heteropolynuclear complexes of the type [M(diamine)2]3[Cr(NCS)6]2_nH2O, where diamine = N-methylethylenediamine (N-Me-en), 1,2-diaminopropane (pn); M = Ni(II), Cu(II) have been prepared by reacting [Cr(NCS)6]3- with the corresponding cationic [M(diamine)2]2+ complex in an aqueous solution. They have been characterized by elemental analysis, IR, UV-VIS, EPR, variable temperature magnetic susceptibility and thermal analysis. Spectroscopic studies reveal thiocyanato bridges between M(II)-Cr(III) centres. The parameters determined from temperature dependence on magnetic susceptibility (80-300 K) indicate moderate antiferromagnetic interactions for Ni(II)-Cr(III) and negligibly small or very weak ones for Cu(II)-Cr(III) systems. Magnetic studies suggest also presence of diamagnetic Ni(II) ions in the structure of Ni(II)-pn-Cr(III) complex. Thermal analysis shows higher thermal stability of Ni(II)-Cr(III) than Cu(II)-Cr(III) compounds. The process of thermal decomposition after dehydration is multistage and yields NiO + NiCr2O4and CuO + CuCrO2 as final products, respectively.

9

Oxidation of 3-Hydroxy-6-methyl-2-pyridinemethanol by Chromium(VI) in Acidic Aqueous Media ; Kinetic and EPR Studies

Kita E., Wrzeszcz G.

Polish Journal of Chemistry

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2003

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Vol. 77 / nr 3

355-364

EN

Kinetics of oxidation of 3-hydroxy-6-methyl-2-pyridinemethanol (hmpol) by CrVI at HClO4 was studied under the pseudo-first-order conditions. The hmpol oxidation products were the appropriate aldehyde (hmpal) and acid (hmpac) coordinated to the chromium( III). The linear dependence of the pseudo-first-order rate constant (kobs) on [hmpol] at 1.0 and 2.0 M HClO4 and a parabolic dependence of kobs on [H+] were established. The apparent activation parameters were determined from the second-order rate constants at 1.0MHClO4. The presence of the CrII and CrIV intermediates was deduced, based on rate retardation effect caused by O2 and MnII respectively, whereas the presence of CrV was established by EPR. Some correlations between the structure and stability of intermediate chromium(V) complexes have been discussed from EPR spectra, recorded during the redox process.

10

Synthesis, Spectroscopy and Magnetism of New -Thiocyanato Polynuclear Copper(II)-Chromium(III) Complexes

Dobrzańska L., Wrzeszcz G., Grodzicki A., Rozpłoch F.

Polish Journal of Chemistry

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2001

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Vol. 75, nr 11

1689-1694

EN

New heteropolynuclear complexes with general formula [Cu(diamine)2]3 [Cr(NCS)6]2źnH2O, where diamine = N,N-dimethylethylenediamine (1,2-dmen), N,N-dimethylethylenediamine (1,1-dmen), N,N-diethylethylenediamine (1,2-deen), N,N-diethylethylenediamine (1,1-deen), 1,3-diaminopropane (tn) were obtained by reactions of [Cr(NCS)6]3– with the corresponding cationic Cu(II) complexes: [Cu(diamine)2]2+ and characterized by spectroscopic methods and magnetic measurements. The formation of end-to-end thiocyanato bridges between tetragonal Cu(II) and pseudo-octahedral Cr(III) is evident from IR and UV-VIS spectra by appearance of new components of ni(CN) band and shifts in the absorption maxima assigned to copper d-d transitions in comparison with corresponding mononuclear complexes. The EPR spectra measured at room temperature on solid samples show broad, symmetric signal at g = 2.02–2.03.Variable-temperature magnetic susceptibility measurements reveal the presence of weak antiferromagnetic interactions in [Cu(1,1-deen)2]3[Cr(NCS)6]2H2O and [Cu(tn)2]3[Cr(NCS)6]22H2O.

11

Synthesis and Properties of New Bimetallic Complexes of General Formula: [Ni(diamine)2]3[Cr(NCS)6]2.nH2O

Dobrzańska L., Wrzeszcz G., Grodzicki A., Rozpłoch F.

Polish Journal of Chemistry

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2001

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Vol. 75, nr 6

909-914

12

New Polymeric Copper(II) Complexes with Tributy I Phosphite and Perfluorinated Carboxylates

Szłyk E., Szymańska I., Kucharek R., Wrzeszcz G., Rozpłoch F.

Polish Journal of Chemistry

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2001

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Vol. 75, nr 2

215-222

EN

New Cu(II) complexes with tributyl phosphite and aliphatic perfluorinated carboxylates [Cu{P(OBu)3}(ž-OH)(ž-RCOO)]n, where R = CF3, C2F5, C3F7, C6F13, C7F15, were obtained and their spectroscopic (UV-VIS, EPR, MS, IR) and thermal properties were studied. Mass spectra were in favour of the bridging coordination carboxylates and monodentate phosphite and suggest a polymeric structure. EPR spectra and magnetic susceptibility measurements indicate the formation of pentacoordinated Cu(II) in polymeric complexes. Examination of COO absorption bands suggests bridging carboxylates as well as a hydroxo group, whereas tributyl phosphite is monodentately bonded. Thermal decomposition is a multistage process, which in nitrogen and air yields a mixture of Cu2O and Cu2P2O7.

13

Synthesis and Characterization of Thiocyanato-Bridged Heteropolynuclear Chromium(III)-Copper(II) Complexes

Dobrzańska L., Wrzeszcz G., Grodzicki A., Rozpłoch F.

Polish Journal of Chemistry

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2000

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Vol. 74, nr 2

199-206

EN

Heteropolynuclear thiocyanate-bridged complexes were prepared in the reactions of aqueous solutions of K3[Cr(NCS)6] with copper(II) complexes of the type [CuX4]2+, where X=imidazole (imH), 4-methylimidazole (4-MeimH) and 2X= ethylenediamine (en). Solid products were formulated as (Cu(imH)4)3(Cr(NCS)6)2 *2H2O, (Cu(4-MeimH)4)3(Cr(NCS)6)2 *3H2O and (Cu(en)2)3(Cr(NCS)6)2 *2H2O on the basis of elemental analysis and spectral data (IR,UV-VIS). EPR spectra, variable temperature magnetic susceptibility and thermal properties in air were investigated, indicating that all complexes are polynuclear with thiocyanate bridges, exhibiting Curie-Weiss behavior between 80-300 K. Thermal decomposition is multistage and yields CuO and CuCrO2 as final products.

14

New Polymeric Copper(II) Complexes with Triphenyl Phosphite and Perfluorinated Carboxylates

Szłyk E., Szymańska I., Wrzeszcz G., Rozpłoch F.

Polish Journal of Chemistry

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2000

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Vol. 74, nr 7

909-918

EN

New Cu(II) complexes with triphenyl phosphite and aliphatic perfluorinated carboxylates [Cu{P(OC6H5)3}(u-OH)(u-RCOO)]n (where R=CF3, C2F5, C3F7, C6F13, C7F15, C8F17, C9F19) were obtainedf and their spectroscopic and thermal properties studied. EPR spectra and magnetic susceptibility measurments indicate the formation of polymeric complexes. Examination of COO absorption bands suggests bridging carboxylates as well as a hydro group, whereas triphenyl phosphite is monodentately bonded. Thermal decomposition is a multistage process, which in nitrogen yields a mixture of Cu, Cu2O and Cu2p2O7 but in air - pure u2P2O7.

15

Synthesis and characterization of diantipyrylmethanium salts of some pseudo-tetrahedral anionic copper(II) complexes

Wrzeszcz G., Grodzicki A., Pawlak R., Rozpłoch F.

Polish Journal of Chemistry

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1998

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Vol. 72, nr 10

2232-2241

EN

The tetrachlorocuprate(II), tetrabromocuprate(II) and tetrakis(izothiocyanate)cuprate(II) complexes of diantipyrylmethanium cations have been prepared and formulated as (H2DAM)CuCl4, (H2DAM)CuBr4, and (HDAM)2Cu(NCS)4 on the basis of spectral data (IR, UV-VIS) and elemental analysis. The EPR spectra, variable temperature magnetic susceptibility and thermal properties in air have been investigated. The results indicate for all complexes a distored tetrahedral configuration. All studied complexes exhibited Curie-Weiss behaviour between 80-300 K. Thermal decomposition is a multistage process and yields CuO as final product.

16

Studies on kinetics and mechanism of oxidation of pyridoxal by dichromates in aqueous HClO4 solutions

Kita E., Kita P., Pietkiewicz A., Wrzeszcz G., Rozpłoch F.

Polish Journal of Chemistry

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1998

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Vol. 72, nr 3

573-581

EN

Oxidation of pyridoxal (PL) by Cr2O7(2-) ion has been studied using an excess of the aldehyde under air or argon atmospheres. The reaction leads mainly to two Cr(III) complexes: [Cr(PA)(H2O)4](2+) and [Cr(H2O)6](3+) and to uncoordinated pyridoxic acid (PA). The rate of PL oxidation follows a mixed third order rate law: first order in concentrations of Cr(VI), Pl and H3O(+). The reduction of Cr(VI) toCr(III) proceeds through chromium(V) intermediate complex, which has been detected by the EPR method. Mechanism of the reaction has been discussed.