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1.
The effect of the nature of organic electron transfer agents and of PtII, PdII, RhII, CoII, NiII, CuII, CrIII, MnII, TiIII, VIII, ZnII, and AgI metal ions on the kinetics of the homogeneous reduction ofgem-dichlorocyclopropanes has been studied. PtII, PdII, RhIII, CoII, and NiII ions accelerate this process, VIII and AgI ions exert practically no effect on the reduction rate, and the rest of the metal ions exhibit inhibitor properties.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1407–1410, August, 1993.  相似文献   

2.
1, 3, 4-Thiadiazol-2, 5-Dithiol als Komplexierungsreagenz. II. Komplexe des NiII, RhI, PdII, PtII, AuIII und CuII Complexes of NiII, RhI, PdII, PtII, AuIII, and CuII with 1, 3, 4-thiadiazole-2, 5- dithiol have been prepared. Probable structures have been proposed for the complexes on the basis of chemical analysis, magnetic susceptibility and spectral data. Crystal field parameters have been calculated which are in keeping with the structures proposed.  相似文献   

3.
Comprehensive studies on the coordination properties of tridentate nitrenium‐based ligands are presented. N‐heterocyclic nitrenium ions demonstrate general and versatile binding abilities to various transition metals, as exemplified by the synthesis and characterization of RhI, RhIII, Mo0, Ru0, RuII, PdII, PtII, PtIV, and AgI complexes based on these unusual ligands. Formation of nitrenium–metal bonds is unambiguously confirmed both in solution by selective 15N‐labeling experiments and in the solid state by X‐ray crystallography. The generality of N‐heterocyclic nitrenium as a ligand is also validated by a systematic DFT study of its affinity towards all second‐row transition and post‐transition metals (Y–Cd) in terms of the corresponding bond‐dissociation energies.  相似文献   

4.
Structural reorganization of polyamide (PA) and low-molecular-weight CuI and CuII complexes with biquinolyl (biQ) ligands during their mutual redox transformations in solution was studied using the electrochemical methods (cyclic voltammetry and preparative electrolysis) and quantum chemical DFT calculations. The influence of electronic factors and geometry distortions in the complexes on the ionization energy on going from CuI to CuII was evaluated in comparison. The catalytically active form of the [CuI(PA)L2]BF4 complex can be synthesized in situ from the stable tetrahedral complex [CuI(PA)2]BF4 by the series of successive redox transitions CuI → CuII → CuI accompanied by the loss of one biQ-containing macroligand. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1331–1340, July, 2007.  相似文献   

5.
In this study, the Schiff base ligands H2L1–H2L3 and their CuII, CoII, NiII, FeIII RuIII and VOIV complexes have been prepared and characterized by spectroscopic and analytical techniques. All the complexes are mononuclear. Keto-enol tautomeric forms of the ligands have been investigated in polar and apolar solvents. The ligands favor the keto-form in the C7H8 and C6H14. The C–C coupling reaction of the 2,6-di-t-butylphenol has been investigated by the CoII and CuII complexes. Thermal properties of the complexes have been assessed using thermal techniques and similar properties were found. In the FeIII and RuIII complexes, firstly, the coordinated water molecule is lost from the complex; in the second step, the chloride ion leaves the molecule in the 300–350 °C temperature range. Finally, the complexes decompose to the appropriate metal oxide at the higher temperature ranges. The electrochemical properties of the complexes have been studied in the two different solvents (DMF and CH3CN).  相似文献   

6.
Summary The chelating behaviour of two biologically active ligands, pyridine-2-carboxaldehyde(4-phenyl) thiosemicarbazone(L1H) and pyridine-2-carboxaldehyde thiosemicarbazone(LH), towards FeIII, CoIII, FeII and RhIII has been investigated. The ligands act as tridentate N–N–S donors, resulting in the formation of bis-chelate complexes of the type MIII(A)2X·nH2O (A=L1 or L; X=Cl, ClO4; M=CoIII, RhIII, FeIII), FeII(L1H)2SO4·2H2O and FeII(L1)2·H2O. Biological activity of the ligands and the metal complexes in the form ofin vitro antibacterial activities towardsE. coli has been evaluated and the possible reasons for enhancement of the activity of ligands on coordination to metal ion is discussed.  相似文献   

7.
FeII, CoIII, NiII, PdII, and RhIII chelates with the N-unsubstituted 1-2-diimine ligands benzildiimine and 9.10-phenanthrenequinonediimine have been prepared. The compounds are characterised chemically, spectroscopically (uv, vis, ir) and polarographically. The results indicate remarkable π-back bonding in the chelates. The unusual magnetic moments of the FeII, CoIII and RhIII chelates are caused by temperature-independent paramagnetism. FeII, CoIII, NiII and CuII chelates of the partially deprotonated phenanthrenequinone diimine are obtained.  相似文献   

8.
The metalation of meso‐tetrakis(pentafluorophenyl)‐substituted [26]rubyrin has been explored with Group 9 metal salts (RhI, CoII, IrIII), affording a Hückel aromatic [26]rubyrin–bis‐RhI complex with a highly curved gable‐like structure, a Hückel antiaromatic [24]rubyrin–bis‐CoII complex that displays intramolecular antiferromagnetic coupling between the two CoII ions (J=?4.5 cm?1), and two Cp*‐capped IrIII complexes; in one, the iridium metal sits on the [26]rubyrin frame with two Ir?N bonds, whereas the other has an additional Ir?C bond, although both IrIII complexes display moderate aromatic character. This work demonstrates characteristic metalation abilities of this [26]rubyrin toward Group 9 metals.  相似文献   

9.
Mehmet Kandaz  At&#x;f Koca 《Polyhedron》2009,28(14):2933-2942
α- and β-substituted tetrakis(6-hydroxyhexylthiol) phthalocyaninato manganese (III) chloride complexes have been prepared via cyclotetramerization. Both complexes have been characterized by elemental analysis, FTIR, MS and UV–Vis spectral data. The voltammetric and in situ spectroelectrochemical studies reveal that both complexes exhibit an oxidation and three reduction processes having reversible, one-electron, and diffusion controlled mass transfer characteristics, which are assigned to MnIIIPc2−/MnIVPc2−, MnIIIPc2−/MnIIPc2−, MnIIPc2−/MnIPc2−, and MnIPc2−/MnIPc3− couples respectively. The existence of oxygen in solution significantly affects the in situ spectroelectrochemical behavior of the complexes due to the formation of μ-oxo MnPc species. An in situ electrocolorimetric method has been applied to investigate the colors of the electro-generated anionic and cationic forms of the complexes for the first time in this study. The complexes, coated on a glassy carbon electrode potentiostatically, show considerable high electrocatalytic activity to hydrogen evolution reactions in aqueous solution.  相似文献   

10.
The formation of CuII–Br–FeIII-type heterobimetallic complexes was observed spectrophotometrically, given the non-additivity of the spectra from the copper(II) and iron(III) complexes. The kinetics of the oxidation of promazine radical (ptz+•) to promazine 5-oxide, by iron(III) bromides, copper(II) bromides, and a mixture of these complexes in acidic aqueous solutions, have been studied using UV–Vis spectroscopy at I = 1.0 M (H+, Cu2+, Fe3+, Br) and T = 318 K. Copper(II) inhibits the oxidation of the promazine radical to promazine sulfoxide using iron(III) complexes. A rate retardation effect, characterized by the dependence of the pseudo second-order rate constant (k II) on the copper(II) concentration k II = a/(1 + b[CuII]), can be rationalized as a result of CuII–Br–FeIII-type heterobimetallic complex formation.  相似文献   

11.
Polyazine‐bridged RuIIRhIIIRuII complexes with two halide ligands, Cl? or Br?, bound to the catalytically active Rh center are efficient single‐component photocatalysts for H2O reduction to H2 fuel, with the coordination environment on Rh impacting photocatalysis. Herein reported is a new, halide‐free RuIIRhIIIRuII photocatalyst with OH? ligands bound to Rh, further enhancing the photocatalytic reactivity of the structural motif. H2 production experiments using the photocatalyst bearing OH? ligands at Rh relative to the analogues bearing halides at Rh in solvents of varying polarity (DMF, CH3CN, and H2O) suggest that ion pairing with halides deactivates photocatalyst function, representing an exciting phenomenon to exploit in the development of catalysts for solar H2 production schemes.  相似文献   

12.
In this work, the differences in catalytic performance for a series of Co hydrogen evolution catalysts with different pentadentate polypyridyl ligands (L), have been rationalized by examining elementary steps of the catalytic cycle using a combination of electrochemical and transient pulse radiolysis (PR) studies in aqueous solution. Solvolysis of the [CoII−Cl]+ species results in the formation of [CoII4-L)(OH2)]2+. Further reduction produces [CoI4-L)(OH2)]+, which undergoes a rate-limiting structural rearrangement to [CoI5-L)]+ before being protonated to form [CoIII−H]2+. The rate of [CoIII−H]2+ formation is similar for all complexes in the series. Using E1/2 values of various Co species and pKa values of [CoIII−H]2+ estimated from PR experiments, we found that while the protonation of [CoIII−H]2+ is unfavorable, [CoII−H]+ reacts with protons to produce H2. The catalytic activity for H2 evolution tracks the hydricity of the [CoII−H]+ intermediate.  相似文献   

13.
In contrast to the UV‐photoinduced ligand photoionization of the flavonoid complexes of FeIII, redox reactions initiated in ligand‐to‐metal charge‐transfer excited states were observed on irradiation of the quercetin ( 1 ) and rutin ( 2 ) complexes of CuII. Solutions of complexes with stoichiometries [CuIIL2] (L=quercetin, rutin) and [CuII2Ln] (n=1, L=quercetin; n=3, L=rutin) were flash‐irradiated at 351 nm. Transient spectra observed in these experiments showed the formation of radical ligands corresponding to the one‐electron oxidation of L and the reduction of CuII to CuI. The radical ligands remained coordinated to the CuI centers, and the substitution reactions replacing them by solvent occurred with lifetimes τ<350 ns. These are lifetimes shorter than the known lifetimes (τ>1 ms) of the quercetin and rutin radical's decay.  相似文献   

14.
A series of polynuclear complexes based on RuII, OsII, ReI and RhIII polypyridine moieties have been prepared in the context of intramolecular energy and electron transfer studies and of interfacial electron transfer with nanocrystalline TiO2. The polynuclear complexes allow for the occurrence of vectorial intramolecular energy and electron transfer and have been proven to be efficient sensitizers of the wide band-gap semiconductor. The performance of photoregenerative cells based on these systems and the dynamics of the excited state intramolecular processes and of the interfacial electron transfer processes are discussed.  相似文献   

15.
Some 6:1 thiocyanate complexes of FeIII, MoIII, RuIII, OsIII, IrIII and some 6:1 or 4:1 selenocyanate complexes of FeII, FeIII, MoIII, RhIII, PdII, PtII, and AuIII have been prepared as salts of large organic cations. The compounds are characterized by their infra-red spectra and by conductance measurements. In particular the linkage property of the thiocyanate and selenocyanate ligand is discussed together with the consequences it has on the AHRLAND -CHATT -DAVIES -PEARSON classification of the central ions.  相似文献   

16.
Summary The stereochemistry and complexation behaviour of diphenyl diketone monothiosemicarbazone (DKTS) with CuII, CoII, NiII, CdII, ZnII, PdII, PtII, RuIII, RhIII and IrIII have been investigated by means of chemical, magnetic and spectral (i.r., Raman, 1H- and 13C-n.m.r. and electronic) studies. The ligand forms complexes of the M(DKTS)2 type with NiII, CuII and CoII having a distorted octahedral geometry. The absence of a v(M—X) band in the i.r. spectra, coupled with their 1:1 electrolytic conductances, suggests that RuIII, RhIII and IrIII form octahedral complexes of the [M(DKTS)2]Cl type. A four-coordinate structure involving bridging halides is proposed for the ZnII, CdII, PdII and PtII complexes, which have relatively low v(M—X) vibration modes.  相似文献   

17.
Azoimidazolium dyes were used as precursors for mesoionic carbene ligands (Azo‐MICs). The properties of these ligands were examined by synthesizing RhI, AuI, and PdII complexes. Experimental (NMR, IR) and theoretical investigations show that Azo‐MICs are potent σ‐donor ligands. Yet, they feature a small singlet–triplet gap and very low‐lying LUMO levels. The unique electronic properties of Azo‐MICs allow for reversible one‐electron reductions of the metal complexes, as evidenced by cyclic voltammetry.  相似文献   

18.
Nickel complexes with new cyclic ligands containing phosphorus and nitrogen atoms as coordination sites are novel efficient catalysts for hydrogen oxidation. A systematic study of their electrochemical properties made it possible to classify the nickel systems in question into four groups according to the sequence of electron transfer processes in the reduction (MII-MI-M0) and to the nature of solvents and counterions. Regularities of catalytic transformations involving nickel complexes with P,N-cyclic ligands in the H2 oxidation reaction in the coordination sphere of the catalyst and a correlation between the structure of the complex and its redox properties were established. The most efficient catalysts contain phenyl and 2-pyridyl substituents at the phosphorus atom and benzyl or 2-pyridyl substituents at the nitrogen atom.  相似文献   

19.
Zeolite-X exchanged with RhIII compounds and activated at 450 °C in O2 contains two paramagnetic species involving rhodium: these, detected by e.s.r, are RhII and superoxides of RhIII. Superoxo-rhodium(III) is formed by the oxidation with O2 of RhII generated in the heat treatment.  相似文献   

20.
The structure, spectroscopic, and electrochemical properties of [Co{(BA)2pn}(L)2]ClO4 complexes, where (BA)2pn = N,N′-bis(benzoylacetone)-1,3-propylenediimine dianion and the two ancillary ligands (L) are pyridine, py (1), and 4-methylpyridine, 4-Mepy (2), have been investigated. These complexes have been characterized by elemental analyses, IR, UV–Vis and 1H-NMR spectroscopy. The crystal structure of [Co{(BA)2pn}(py)2]ClO4 (1) has been determined by X-ray diffraction. The coordination geometry around cobalt(III) is best described as a distorted octahedron. The electrochemical reduction of these complexes at a glassy carbon electrode in acetonitrile solution indicates that the first reduction process corresponding to CoIII–CoII is electrochemically irreversible, which is accompanied by the dissociation of the axial N(py)–cobalt bonds. This process becomes quasi-reversible upon the addition of excess py ligands. The second reduction step of CoII/I shows reversible behavior and is not influenced by the nature of the axial ligands. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

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