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1.
Photolysis of highly photo-labile corrole-manganese(IV) nitrites by visible light was studied in three corrole systems with different electronic environments. As observed in all three systems, homolytic cleavage of ON bond of nitrite ligand resulted in one-electron photo-oxidation to generate manganese(V)-oxo corroles, as determined by their distinct UV–vis spectra and kinetic behaviors. The spectral and kinetic results are rationalized by a multiple oxidation model, where the electron-demand MnV-oxo species may serve as direct two-electron oxidant for oxygen atom transfer reactions and less electron-demand systems undergo a disproportionation reaction to form a putative manganese(VI)-oxo corrole as the true oxidant. 相似文献
2.
Non-heme Fe(IV)-oxo intermediates 总被引:1,自引:0,他引:1
High-valent non-heme iron-oxo intermediates have been proposed for decades as the key intermediates in numerous biological oxidation reactions. In the past three years, the first direct characterization of such intermediates has been provided by studies of several alphaKG-dependent oxygenases that catalyze either hydroxylation or halogenation of their substrates. In each case, the Fe(IV)-oxo intermediate is implicated in cleavage of the aliphatic C-H bond to initiate hydroxylation or halogenation. The observation of non-heme Fe(IV)-oxo intermediates and Fe(II)-containing product(s) complexes with almost identical spectroscopic parameters in the reactions of two distantly related alphaKG-dependent hydroxylases suggests that members of this subfamily follow a conserved mechanism for substrate hydroxylation. In contrast, for the alphaKG-dependent non-heme iron halogenase, CytC3, two distinct Fe(IV) complexes form and decay together, suggesting that they are in rapid equilibrium. The existence of two distinct conformers of the Fe site may be the key factor accounting for the divergence of the halogenase reaction from the more usual hydroxylation pathway after C-H bond cleavage. Distinct transformations catalyzed by other mononuclear non-heme enzymes are likely also to involve initial C-H bond cleavage by Fe(IV)-oxo complexes, followed by diverging reactivities of the resulting Fe(III)-hydroxo/substrate radical intermediates. 相似文献
3.
Binuclear O-bridged titanium(IV) complexes of phenylenediamine-bis(phenolato) ligands were obtained from the corresponding ligands and Ti(OiPr)4 and analyzed by 1H, 13C and diffusion NMR. The comparative hydrolytic stability in 1:9 D2O/DMSO-d6 was assessed by 1H NMR, and the complexes featured t1/2 values of above 100 h. The cytotoxic activity of the binuclear complexes was measured toward human colon HT-29 cancer cell line by the MTT assay. Although as expected most complexes exhibited mild or no cytotoxic activity, one leading complex demonstrated marked activity with IC50 value of 77 ± 40 μM. 相似文献
4.
5.
Dinuclear iron(III) complexes, [(phenO)Fe(SO4)]2·2CH3OH (1) and [(bpmapO)Fe(NO3)]2(NO3)2·3CH3OH (2) have been prepared by the reaction of phenOH/bpmapOH and FeSO4·7H2O/Fe(NO3)3·9H2O in methanol, respectively (phenOH = N-(2-pyridylmethyl)-N′-(2-hydroxyethyl)ethylenediamine, bpmapOH = N-(bis(2-pyridylmethyl)amino)-2-methylpropan-2-ol). Both complexes are ethoxy-bridged dinuclear species and the iron(III) ions in 1 and 2 have distorted octahedral geometries. Both complexes show strong antiferromagnetic interactions through the bridged ethoxy groups within the dimeric units. 相似文献
6.
Carlos L. P. Carone Fabiana C. Fim Rubens Bisatto Vanusca D. Jahno Cristóvão Lemos Nara R. S. Basso Sandra Einloft Griselda Barrera Galland 《应用聚合物科学杂志》2008,110(1):270-275
In this research, we describe the application of the complexes o‐C6H4(NSiMe3)2ZrCl2 ( 1 ), o‐C6H4(NSiMe3)2TiBr2 ( 2 ), o‐C6H4(NSiMe3)2TiCl2 ( 3 ), C2H4(NSiMe3)2ZrCl2 ( 4 ), in the ethylene polymerization with different Al/M ratios and temperatures. These complexes presented significant catalytic activities in the presence of methyaluminoxane (MAO) as cocatalyst and toluene as solvent, producing high molecular weight linear polyethylenes. Zirconium complexes were more active at 60°C and titanium complexes at 40°C. Zirconium complex ( 1 ) showed the best values of activity (347 kg PE/mol Zr h atm) for Al/Zr ratio of 340 and 60°C of temperature. In ethylene‐1‐hexene copolymerization, the best result was also reached with catalyst 1 , at the same conditions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
7.
《Inorganic chemistry communications》2007,10(2):229-233
Ru(II) and Zn(II) complexes of multicomponent ligands have been synthesised and characterised incorporating triazine-based coordinating motifs with pendant phenanthryl and phenyl–phenanthryl groups. At room temperature the ligands emit from intra-ligand charge-transfer (ILCT) states, the energy of which may be lowered significantly by metal–ion coordination (e.g. Zn(II)). The ILCT state is efficiently quenched in the Ru(II) complexes by energy transfer to a low-lying metal–ligand charge-transfer 3MLCT state. 相似文献
8.
In analogy to peroxide, disulfide is an oxidant as well as a reductant. Accordingly, as a ligand of a reducing metal center, low-energy MLCT transitions can occur, while with oxidizing metals low-energy LMCT transitions should be observed. Such MLCT and LMCT excitations are expected to induce redox reactions. The complexes [CpFe(II)(CO)2]2μ-S2 (CpC5H5) and {[Fe(III)(CN)5]2μ-S2}6 − are suitable examples to explore this behavior. 相似文献
9.
《Inorganic chemistry communications》2002,5(11):993-995
The closed-shell metalloporphyrins Hf(TPP)(OAc)2 and Th(TPP)(acac)2 (TPP=dianion of tetraphenylporphyrin, OAc=acetate, acac=acetylacetonate) display intraligand fluorescence and additional heavy-atom-induced intraligand phosphorescence, which is observed at room temperature in fluid solution and very efficiently quenched by O2 with potential significance for the sensing of trace amounts of dioxygen. 相似文献
10.
《Journal of Sulfur Chemistry》2013,34(4):434-449
Reaction of VOSO4 with 2-hydroxy-napthaldeyde-S-R-thiosemicarbazones (R: methyl, ethyl, propyl or allyl) and salicyl aldehyde yielded five-coordinate oxovanadium(IV) complexes having a N1,N4-diarylidene-S-R-thiosemicarbazidato structures. The compounds were characterized by elemental analysis, magnetic measurements, electronic, infrared, 1H-NMR, and electron paramagnetic resonance (EPR) spectra. The X-band EPR signals were recorded from powder forms and also in solution. All the complexes have a single asymmetric line shape and theoretical fit studies prove the presence of axial symmetry around the paramagnetic vanadium ions. A computer simulation of the EPR spectrum of each complex was carried out to derive the related EPR parameters. Cyclic voltammograms of the complexes exhibited two metal-based reversible redox peaks around 500 and ?800?mV corresponding to one electron oxidation/reduction of VIVO/VVO and VIVO/VIIIO, respectively. The reductive response in the 50–350?mV region was assigned to ligand reduction. Antioxidant activities of the compounds were determined with CUPric Reducing Antioxidant Capacity, 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid, and 1,1-diphenyl-2-picrylhydrazyl assays. The test results indicated that the antioxidant capacity of the compounds increases with the carbon number of saturated hydrocarbon chain on sulfur atom. 相似文献
11.
A pair of mononuclear iron(II) enantiomeric complexes: fac-Λ-[Fe(R-L)3](BF4)2·MeCN (1) and fac-Δ-[Fe(S-L)3](BF4)2·MeCN (2) [L = 1-phenyl-N-(1-methyl-imidazol-2-ylmethylene)ethanamine] have been synthesized and characterized. X-ray crystallography reveals that iron(II) center is surrounded by three bidentate ligands defining a pseudooctahedral [FeN6] coordination environment. R-L ligand induces the fac-Λ isomer, while S-L ligand induces the fac-Δ isomer. Magnetic measurements reveal that both of them display obviously spin-crossover behavior at 365 K. After desolvation, they exhibit a reversible spin transition with a small hysteresis loop of ca. 3 K appearing at about T1/2↑ = 222 K and T1/2↓ = 219 K. 相似文献
12.
《Inorganic chemistry communications》2002,5(1):1-4
Gallium(III) and indium(III) complexes of cross-bridged cyclam and cyclen tetraaza macrocyclic ligands have been prepared and structurally characterized. In the crystalline state, both the GaCl3 (cross-bridged cyclam) and InBr3 (cross-bridged cyclen) complexes feature hexacoordinate cations in cis-folded tetradentate ligand clefts with ancillary cis-dihalides. These represent the first well-characterized gallium and indium halide complexes of tetraazamacrocycles. 相似文献
13.
New unsymmetrical chiral salen complexes were synthesized and the efficiency of Mn(III), Ti(IV), Co(II) and Co(III) type catalysts
were examined in the enantioselective epoxidation of styrene and α‐methylstyrene, the trimethylsilylcyanation of benzaldehyde,
the borohydride reduction of aromatic ketones and asymmetric hydrolysis of epoxides to diols, respectively. A very high level
of enantioselectivity was attainable over the unsymmetrical chiral salen complexes prepared mainly from salicylaldehyde and
2‐formyl‐4,6‐di‐tert‐butylphenol derivatives. Enantiomeric excess of the corresponding reaction product obtained using unsymmetrical
chiral salen catalysts was generally higher than that over conventional symmetric chiral salen catalysts.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
14.
《Inorganic chemistry communications》2005,8(1):41-43
The reactions of C5H4NCHNNHC(O)Ph (1) with Fe(II) chloride gave [Fe2(C5H4NC(OEt)NNHC(O)Ph)2(μ-OEt)2Cl2]) (2) in ethanol and [Fe2(C5H4NC(OMe)NNHC(O)Ph)2(μ-OMe)2Cl2] (3) in methanol as well as [Fe(C5H4NCHNNHC(O)Ph)Cl2] (4) in tetrahydrofuran, respectively. The X-ray diffraction analysis reveals their structures and complex 4 is proposed as an intermediate of formation of complexes 2 and 3. 相似文献
15.
Iron(III) complexes of dimethyldithiocarbamate and imidazolyl dithiocarbamate were synthesized and characterized by elemental analyses, FTIR, UV–VIS and the ligands by NMR spectroscopy. The complexes were thermolysed as single molecule precursors at 180°C to prepare octadecylamine (ODA) capped iron sulfide nanocrystals and iron sulfide-hydroxyethyl cellulose (HEC) composites. UV–VIS, PL, FTIR, P-XRD, HRTEM, FESEM and EDS were used to characterize the iron sulfide nanocrystals and corresponding HEC nanocomposites. XRD confirmed iron sulfide nanocrystal (NP1) from dimethyldithiocarbamate to be hexagonal pyrrhotite-5H, Fe9S10 crystalline phase while iron sulfide nanocrystals (NP2) from imidazolyl dithiocarbamate is in pyrrhotite, Fe11S12 crystalline phase. TEM images show that the iron sulfide nanocrystals have particle sizes in the range 24–32?nm for NP1 and 18–25?nm for NP2 iron sulfide nanocrystals. The optical band gaps of the iron sulfide nanocrystals obtained from Tauc plots are 3.83 and 4.16?eV for NP1 and NP2, respectively. IR spectra, FESEM surface morphology and EDS spectra of iron sulfide/HEC composites confirmed dispersion of the iron sulfide nanocrystals within the hydroxyethyl cellulose (HEC) matrix. 相似文献
16.
《Inorganic chemistry communications》2007,10(10):1154-1158
Three amino(polyphenolic) ligands, N,N′-bis(5-tert-butyl-2-hydroxybenzyl)-1,2-diaminoethane 1, tris(5-tert-butyl-2-hydroxy-3-methylbenzyl)amine 3, its 3-chloro analogue 4 and their ZrIV complexes have been synthesised. The crystal structure of the ZrIV complex of tris(5-tert-butyl-3-chloro-2-hydroxybenzyl)amine, shows this to be [Zr(4-2H)2] in which both ligands exists in a zwitterionic form with one alkylammonium and three phenolate groups. The complexes are stable in a two phase, chloroform/water, system at high pH, but the zirconium is stripped at pH < 2.5. The pH value needed to strip 50% of the ZrIV from the complex [Zr(1-4H)] of the tetraphenolic ligand is ∼2.0 whilst the complexes [Zr(3-2H)2] and [Zr(4-2H)2] of the triphenolic ligands are slightly more stable with pH1/2 values of ∼1.4. We were unable to use the ligands to extract zirconium from low pH aqueous zirconium oxychloride solutions into an organic phase under a variety of conditions. 相似文献
17.
Biswajit Deb Bibek Jyoti Borah Bhaskar Jyoti Sarmah Babulal Das Dipak Kumar Dutta 《Inorganic chemistry communications》2009,12(9):868-871
The hexa-coordinated chelate complexes of the type [Ru(CO)2Cl2(P-P)](1a,b) [where P-P = 9,9-dimethyl-4,5-bis(diphenylphosphino)xanthene(a) and [bis(2-diphenylphosphinophenyl)ether(b)] have been synthesized by reacting the polymeric precursor [Ru(CO)2Cl2]n with the ligands in 1:1 molar ratio. The complexes 1a,b are characterized by elemental analyses, Mass, IR and NMR spectroscopy together with the single crystal X-ray structure determination of 1a. The compound 1a crystallizes in a monoclinic system with space group C2/c showing a slightly distorted octahedral geometry around the Ru centre. The complexes 1a and 1b are thermally stable up to 300 °C and exhibit high catalytic activity in transfer hydrogenation of aldehyde and ketones to corresponding alcohols. The complexes 1a and 1b show much higher catalytic activity for the hydrogenation of aldehyde than ketones. In general, the catalytic efficiency of 1b is higher compared with 1a. 相似文献
18.
19.
Kenji Hanabusa Atsushi Nakamura Toshiki Koyama Hirofusa Shirai 《Polymer International》1994,35(3):231-238
Electroactive 2,2′: 6,2″-terpyridinyl ligands ( 3, 5, 6 ) and their iron(II) ( 7a–9a ) and ruthenium(II) complexes ( 7b–9b ) were synthesized. Bis[3-(aminophenyl)-2,2′ :6,2″-terpyridinyl]metal(II) complexes ( 7a, 7b ) and bis[2-(hydroxyphenyl)-2,2′ :6,2″-terpyridinyl]metal(II) complexes ( 8a, 8b ) were electropolymerized on to the surface of Pt or In-SnO2 (ITO) electrodes in acetonitrile containing Bu4NCIO4 by scanning the potential between O and + 1.6V (for 7a and 7b ), and ?0.8 and +1.6V (for 8a and 8b ) versus saturated calomel electrode. The electrodes obtained by electropolymerization exhibited reversible electrochromism based on Fe(II)/Fe(III) or Ru(II)/Ru(III) redox couple. Photoresponses to visible light were found in the modified electrode obtained by electropolymerization of ruthenium complex 7b in an aqueous LiClO4 solution containing methylviologen (cation MV2+) under an O2 atmosphere. The mechanism for the photoresponded cathodic current was explained in terms of an excitation of bis(terpyridinyl)ruthenium(II) complex [Ru(terpy)22+] by visible light, an electron transfer from the excited state [Ru(terpy)2+*2] to MV2+, reduction of Ru(terpy)3+2 at an electrode, and oxidation of MV+* with O2. 相似文献
20.
Prudence Tau 《Electrochimica acta》2007,52(11):3641-3650
The synthesis and electrochemical characterisation of the following oxotitanium tetra-substituted phthalocyanines are reported: 1,(4)-(tetrabenzyloxyphthalocyaninato)titanium(IV) oxide (5a); 1,(4)-{tetrakis[4-(benzyloxy)phenoxy]phthalocyaninato}titanium(IV) oxide (5b); 2,(3)-(tetrabenzyloxyphthalocyaninato)titanium(IV) oxide (6a) and 2,(3)-{tetrakis[4-(benzyloxy)phenoxy]phthalocyaninato}titanium(IV) oxide (6b). The electrochemical characterisation of complexes octa-substituted with 4-(benzyloxy)phenoxy (9b), phenoxy (9c) and tert-butylphenoxy (9d) groups is also reported. The cyclic voltammograms of the complexes exhibit reversible couples I-III and couple IV is quasi-reversible for complexes 5a, 5b, 6a and 6b. The first two reductions are metal-based processes, confirmed by spectroelectrochemistry to be due to TiIVPc2−/TiIIIPc2− and TiIIIPc2−/TiIIPc2− redox processes and the last two reductions are ring-based processes due to TiIIPc2−/TiIIPc3− and TiIIPc3−/TiIIPc4−. Chronocoulometry confirmed a one-electron transfer at each reduction step. The electrochemistry of the above complexes is also compared to the previously reported 5c, 5d, 6c and 6d. 相似文献