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1.
《Inorganica chimica acta》1988,149(1):105-110
The compounds Ta2Cl4(dmpe)2(μ-Me2S)(μ-O) (1) and Ta2Cl4(py)4(μ-THT)(μ-O) (2) where dmpe = Me2PCH2CH2PMe2 and THT = tetrahydrothiophene, have been prepared and structurally characterized. They are authentic examples of μ-O bridged TaIIITaIII edge-sharing bioctahedral complexes. Their structures are virtually identical with respect to all of the bonds that they have in common. However, the structure of 1 differs significantly in its TaTa, TaO and one type of TaCl distance from the previously reported Ta2Cl4(dmpe)2(μ-Me2S)(μ-O)·HCl (3). These differences show that in 3 there is a μ-OH group hydrogen bonded to a Cl− ion. The structural differences attendant upon the μ-OH ⇌ μ-O change are of general interest and are discussed. The crystallographic data for the new compounds are as follows: 1: monoclinic (P21/c) with a = 10.412(2), b = 14.749(2), c = 22.177(3) Å, β = 99.25(1)°, V = 3361(1) Å3 and Z = 4. 2: monoclinic (P21/a) with a = 18.238(4), b = 10.402(3), c = 19.070(2) Å, β = 95.37(2), V = 3602(2) Å3 and Z = 4. 相似文献
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《Inorganica chimica acta》1988,152(2):107-110
The dinuclear RhIIRhII complex with proline [Rh2(pro4][NEt4]2 was synthesized and its structure studied by means of spectroscopic (IR, EPR and ESCA) and magnetochemical methods. It was shown that two proline molecules serve as bridging ligands, while the other two are only axially coordinated through their N atoms. 相似文献
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A. A. Chukalovsky T. V. Rakhimova K. S. Klopovsky N. A. Popov Yu. A. Mankelevich O. V. Proshina 《Plasma Physics Reports》2014,40(1):34-51
Available data on the kinetic processes in H2-O2-O2(a 1Δ g ) mixtures are analyzed theoretically, and the ranges in which the rate constants of these processes can vary are determined. The processes of energy transformation in an O2(a 1Δ g )-H2-H-HO2 system in the approximations of the fast and slow (in comparison with the vibrational relaxation time of the HO2 radical) quenching of the electronically excited state are considered. The experiments on the quenching of singlet delta oxygen (SDO) molecules O2(a 1Δ g ) excited in a microwave discharge at a temperature of 300 K and pressure of 6 Torr in a lean hydrogen-oxygen mixture are simulated (by a lean fuel mixture is meant a mixture in which the ratio of the fuel to the oxidizer mass fraction is less than the stoichiometric ratio, which is 2: 1 for a hydrogen-oxygen mixture). It is shown that, over the experimental observation times, the SDO quenching frequency depends on the concentration of molecular hydrogen, the residual odd oxygen fraction in the gas flow, and the ratio between the rate constants of kinetic processes involving HO2 and HO2* radicals. Simulations of the microwave discharge and the transport of excited oxygen along the drift tube make it possible to determine the residual odd oxygen concentration in the gas flow. Recommendations on the choice of the rate constants for the O2(a 1Δ g ) + HO2)A″, v3″ = 0) ? O2 + HO2*(A′, v3′ = 1), HO2*(A′v3′ ≤ 1) + O2(a 1Δ g ) → HO2*(A′,v3′ ≥ 6) + O2, and HO2*(A′,v3′ ≤ 1) + O2(a 1Δ g ) → H + O2 + O2 processes are given. It is shown that, in the case of slow quenching in a H2-O2-O2(a 1Δ g ) mixture at a low temperature, the intensity of hydrogen oxidation is enhanced due to the reaction + HO2*(A′,v3′ ≤ 1) + O2(1Δ) → H + O2 + O2. 相似文献
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Absorption of the biomimetic chromium cation triaqua-μ3-oxo-μ-hexapropionatotrichromium(III) in rats
The cation [Cr3O(O2CCH2CH3)6(H2O)3]+ has been shown in vitro to mimic to the oligopeptide chromodulin’s ability to stimulate the tyrosine kinase activity of insulin
receptor and shown in healthy and type 2 diabetic model rats to increase insulin sensitivity and decrease plasma total and
low-density lipoprotein cholesterol and triglycerides concentrations. However, the degree to which the complex is absorbed
after gavage administration to rats had not been previously determined. The biomimetic cation at nutritional supplement levels
is absorbed with greater than 60% efficiency, and at pharmacological levels, it is absorbed with greater than 40% efficiency,
an order of magnitude greater absorption than that of CrCl3, Cr nicotinate, or Cr picolinate, currently marketed nutritional supplements. The difference in degree of absorption is readily
explained by the stability and solubility of the cation. 相似文献
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《Inorganica chimica acta》1988,154(2):201-207
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《Inorganica chimica acta》1986,122(2):199-205
The X-ray structures of two binuclear copper(II) chloride complexes of the tetradentate ligands 1,4- bis(4,6-dimethyl-2-pyridylamino)phthalazine (PAP46Me) and 3,6-bis(2-pyridylthio)pyridazine are reported. [Cu2(PAP46Me)Cl4] (1) and [Cu2(PTP)Cl4]· CH3CH2OH (2) contain triply bridged binuclear centres involving a diazine (NN) and two chlorobridges with copper-copper separations in the fange 3.19–3.25 Å and distorted square pyramidal copper stereochemistry. The reduced room temperature magnetic moments indicate antiferromagnetically coupled binuclear copper(II) centres.Complex 1 forms green crystals with a= 15.795(3), b=10.661(3), c=16.155(4) Å, β= 113.82(3)°, C2/c, Z = 4, Rf=0.031. Complex (2) forms green crystals with a=33.9022(8), b= 9.1626(5), c= 15.7885(5) Å,β= 114.853(2)°, C2/c, Z=8, Rf=0.047. The structure of the ligand PTP is also reported and compared with that of 2. 相似文献
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The series of complexes [Mn(IV)(X-SALPN)(2-O)]2, 1: X=5-OCH3; 2: X=H; 3: X=5-Cl; 4: X=3,5-diCl; 5: X=5-NO2, contain [Mn2O2]4+ cores with Mn-Mn separations of 2.7 . These molecules can be protonated to form [Mn(IV)(X-SALPN)(2-O,OH)]2
+ in which a bridging oxide is protonated. The pKa values for the series of [Mn(IV)(X-SALPN)(2-O,OH)]2
+ track linearly versus the shift in redox potential with a slope of 84 mV/pKa. This observation suggests that the [Mn2O2]4+ core can be considered as a unit in which the free energy of protonation is directly related to the ability to reduce the Mn(IV) ion. The marked sensitivity of the reduction potential to the presence of protons presents a mechanism in which an enzyme can control the oxidizing capacity of an oxo manganese cluster by the degree and timing of oxo bridge protonation.Abbreviations AnH+CF3SO3
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anilinium triflate
- DMA
N,N-dimethyl acetamide
- H2SALPN
1,3-bis(salicylideneiminato)propane
- H2(5-Cl-SALPN)
1,3-bis(5-chlorosalicylideneiminato)propane;
- H2(3,5-diCl-SALPN)
1,3-bis(3,5-dichlorosalicylideneiminato)propane
- H2(5-NO2-SALPN)
1,3-bis(5-nitorosalicylideneiminato)propane
- H2(5-OMe-SALPN)
1,3-bis(5-methoxysalicylideneiminato)propane
- LuH+CF3SO3
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2,4-lutidinium triflate
- ME3NH+Ph4B-
trimethylammonium tetraphenylborate
- OEC
oxygen evolving complex
- PyH+ClO4
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pyridinium perchlorate
- SCE
saturated calomel electrode 相似文献
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Stella Manta Vanessa Parmenopoulou Christos Kiritsis Athina Dimopoulou Nikolaos Kollatos Ioannis Papasotiriou 《Nucleosides, nucleotides & nucleic acids》2013,32(7):522-535
This article describes the synthesis of (3 ′S) and (3 ′R)-3 ′-amino-3 ′-deoxy pyranonucleosides and their precursors (3 ′S) and (3 ′R)-3 ′-azido-3 ′-deoxy pyranonucleosides. Azidation of 1,2:5,6-di-O-isopropylidene-3-O-toluenesulfonyl-α-D-allofuranose followed by hydrolysis and subsequent acetylation afforded 3-azido-3-deoxy-1,2,4,6-tetra-O-acetyl-D-glucopyranose, which upon coupling with the proper silylated bases, deacetylation, and catalytic hydrogenation, obtained the target 3 ′-amino-3 ′-deoxy-β-D-glucopyranonucleosides. The desired 1-(3 ′-amino-3 ′-deoxy-β-D-allopyranosyl)5-fluorouracil was readily prepared from the suitable imidazylate sugar after azidation followed by a protection/deprotection sequence and reduction of the unprotected azido precursor. No antiviral activity was observed for the novel nucleosides. Moderate cytostatic activity was recorded for the 5-fluorouracil derivatives. 相似文献
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Hydrolysis of nucleic acids is of fundamental importance in biological sciences. Kinetic and theoretical studies on different substrates wherein the phosphodiester bond combined with alkyl or aryl groups and sugar moiety have been the focus of attention in recent literature. The present work focuses on understanding the mechanism and energetics of alkali metal (Li, Na, and K) catalyzed hydrolysis of phosphodiester bond in modeled substrates including Thymidylyl (3′-O, 5′-S) thymidine phosphodiester (Tp-ST) (1), 3′-Thymidylyl (1-trifluoroethyl) phosphodiester (Tp-OCH2CF3) (2), 3′-Thymidylyl (o-cholorophenyl) phosphodiester (Tp-OPh(o-Cl)) (3) and 3′-Thymidylyl(p-nitrophenyl) phosphodiester (Tp-OPh(p-NO2)) (4) employing density functional theory. Theoretical calculations reveal that the reaction follows a single-step (ANDN) mechanism where nucleophile attack and leaving group departure take place simultaneously. Activation barrier for potassium catalyzed Tp-ST hydrolysis (12.0 kcal mol?1) has been nearly twice as large compared to that for hydrolysis incorporating lithium or sodium. Effect of solvent (water) on activation energies has further been analyzed by adding a water molecule to each metal ion of the substrate. It has been shown that activation barrier of phosphodiester hydrolysis correlates well with basicity of leaving group. Figure
Phosphodiester bond in Tp‐ST (1), Tp‐OCH2CF3 (2) Tp‐OPh(o‐Cl) (3) and Tp‐OPh(p‐NO2) (4) 相似文献
16.
《Inorganica chimica acta》1987,128(1):75-80
The preparation and properties of binuclear complexes containing the pyrazolate and azide groups as bridging ligands are reported. Representative formulae are: M2(μ-pz)(μ-N3)(CO)4, M2(μ-pz)(μ-N3)- (COD)2 (M = Rh or Ir), (CO)2Rh(μ-pz)(μ-N3)ML2 (M = Rh, L2 = COD, M = Ir, L = CO) and (η3-C3H5)- Pd(μ-pz)(μ-N3)Rh(CO)2. The crystal and molecular structure of the latter complex has been determined by single-crystal X-ray methods. Crystals are monoclinic, space group C2/c with cell constants a = 18.4750(10), b = 10.0351(3), c = 13.6399(6) Å, α = 90, β = 100.022(4), γ = 90°, and Z = 8. The final R and Rw values were 0.051 and 0.062 for 1417 observed reflexions. This binuclear compound packs in the crystal zig-zag chains of rhodium atoms, along the c axis, wtth intermolecular Rh···Rh contacts of 3.290(1) and 3.604(1) Å. The Rh···Rh···Rh angle is 163.16(4)°. 相似文献
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Two phenoxo bridged dinuclear Cu(II) complexes, [Cu2L2(NO2)2] (1) and [Cu2L2(NO3)2] (2) have been synthesized using the tridentate reduced Schiff-base ligand 2-[(2-dimethylamino-ethylamino)-methyl]-phenol (HL). The complexes have been characterized by X-ray structural analyses and variable-temperature magnetic susceptibility measurements. The structures of the two compounds are very similar having the same tridentate chelating ligand (L) and mono-dentate anionic ligand nitrite for 1 and nitrate for 2. In both complexes Cu(II) is penta-coordinated but the square pyramidal geometry of the copper ions is severely distorted (Addison parameter (τ) = 0.33) in 1 while the distortion is quite small (average τ = 0.11) in 2. These differences have marked effect on the magnetic properties of two compounds. Although both are antiferromagnetically coupled, the coupling constants (J = −140.8 and −614.7 cm−1 for 1 and 2, respectively) show that the coupling is much stronger in 2. 相似文献
18.
Masahiro Ebihara Naohiro Kanematsu Toshiharu Sakuma Shinya Noritake Takashi Kawamura 《Inorganica chimica acta》2005,358(7):2174-2182
Seven diiridium(II) complexes were synthesized by ligand substitution reactions of [Ir2(μ-O2CMe)2Cl2(CO)2] (1) and [Ir2(μ-O2CMe)2Cl2(CO)2(py)2] (2).The reaction of 2 with the silver salt of a less coordinating anion, AgSbF6, gave a cationic complex [Ir2(μ-O2CMe)2Cl(CO)2(py)3]SbF6 (3).A tricarbonyl cationic complex [Ir2(μ-O2CMe)2(CO)3Cl(py)2]SbF6 (4) was obtained under a CO atmosphere.Complex 2 reacted with AgO2CCF3 to give [Ir2(μ-O2CMe)2Cl(O2CCF3)(CO)2(py)2] (5) in toluene.[Ir2(μ-hiq)2(CO)2Cl2] (Hhiq = 1-hydroxyisoquinoline, 6) was synthesized by the bridging-ligand substitution of 1 with Hhiq.Its axial adducts [Ir2(μ-hiq)2Cl2(CO)2L2] (L = Mepy (4-methylpyridine), 7 or PPh3, 8) were synthesized by addition of the ligands to a suspension of 6.In the structures of 7 and 8, two iridium atoms are bridged by two hiq ligands in a head-to-tail arrangement.The reaction of 1 with Hmhp (2-hydroxy-4-methylpyridine) led to triply bridged [Ir2(μ-mhp)3(CO)2Cl(Hmhp)] (9).In complex 9, all the mhp ligands bridge between the Ir atoms in a head-to-head manner.The Ir-Ir distances of 3, 4, 5, 7 and 8 are 2.6047(7), 2.6216(9), 2.5899(9), 2.5933(5) and 2.634(2) Å, respectively, which are similar to those observed in[Ir2(μ-O2CMe)2Cl2(CO)2L2]. The Ir-Ir distance of 2.5512(4) Å in 9 is shorter than in the other complexes. 相似文献
19.
《Inorganica chimica acta》1986,119(1):55-59
The reaction of Fe3(CO)12 with N-methyl-4- mercaptopiperidine gives the title compound. Crystals are monoclinic, space group P21/c with a = 12.922(2), b = 14.784(5), c = 13.607(2) Å, β = 112.41(1)°. With Z = 4 the calculated density is 1.49 g cm−3. Solution of the structure by direct methods led to a final weighted R factor of 0.029 for 2270 independent reflections. The FeFe bond length is 2.534(1) Å and the S···S distance of 2.940(1) suggests bonding interactions. By heating upon reflux in toluene during 10 h, the IR spectrum of the chromatographed solution indicates the syn isomer formation. The reaction with CH3I and HClO4 produces the methylation and protonation, respectively, of the nitrogen atoms of the piporidine rings giving rise to the formation of the [Fe(μ-(CH3)2NC5H9S)(CO)3]2I2·2H2O and [Fe(μ-HCH3NC5H9S)(CO)3]2·H2O·CH3OH compounds. 相似文献