One‐electron reduction of mononuclear nonheme iron(III) hydroperoxo (FeIII OOH) and iron(III) alkylperoxo (FeIII OOR) complexes by ferrocene (Fc) derivatives resulted in the formation of the corresponding iron(IV) oxo complexes. The conversion rates were dependent on the concentration and oxidation potentials of the electron donors, thus indicating that the reduction of the iron(III) (hydro/alkyl)peroxo complexes to their one‐electron reduced iron(II) (hydro/alkyl)peroxo species is the rate‐determining step, followed by the heterolytic O O bond cleavage of the putative iron(II) (hydro/alkyl)peroxo species to give the iron(IV) oxo complexes. Product analysis supported the heterolytic O O bond‐cleavage mechanism. The present results provide the first example showing the one‐electron reduction of iron(III) (hydro/alkyl)peroxo complexes and the heterolytic O O bond cleavage of iron(II) (hydro/alkyl)peroxo species to form iron(IV) oxo intermediates which occur in nonheme iron enzymatic and Fenton reactions. 相似文献
The reaction of VI2 or TiI3, respectively, with ammonia in the presence of traces of water or oxygen, respectively, leads to [(NH3)5M? O? M(NH3)5]I4 · NH3 with M = V, Ti. Their structures were solved by X-ray single crystal data: Pbca (No. 61), Z = 4, M = V: a = 12.482(4) Å, b = 14.819(6) Å, c = 13.286(5) Å, N(F ? 3σF) = 983, N(variables) = 88, R/Rw = 0.053/0.063, M = Ti: a = 12.628(4) Å, b = 14.970(4) Å, c = 13.359(3) Å, N(F ? 3σF) = 1188, N(variables) = 88, R/Rw = 0.043/0.047. The structures consist of corner sharing octahedra double units [(NH3)5M? O? M(NH3)5]4+ with eclipsed conformation which are stacked together according to the motif of a distorted cubic face centered arrangement for the bridging oxygen atoms. IR spectroscopic investigations of the undeuterated vanadium compound and of 5% deuterated samples hint to N? H … I hydrogen bridge bonds and to remarkable π-bonding between the transition metal and the bridging oxygen atoms. 相似文献
Freshly generated solutions of iodine azide (IN3) and iodine isocyanate (INCO) in acetonitrile or carbon tetrachloride add oxidatively to tertiaryaryl derivatives of group VB elements, Ar3M (Ar = Ph, p-tolyl, p-ClC6H4 or p-FC6H4, and M = As, Sb or Bi) and diaryltellurium(II), Ar2Te (Ar = Ph or p-CH3OC6H4) at −10°C to −5°C to give stable covalent monomeric products, Ar3MIX and Ar2TeIX, respectively (where X = N3 or NCO). The mode of bonding of the pseudohalide group to M has been established by solid-state IR spectra. Ar3MI(N3) failed to react with CS2 but reaction with PhNCY (Y = O or S) gave cyclic tetrazole derivatives. Contrasting behaviour was also observed in the metathetic reaction of Ar2MIX and Ar2TeIX with silver pseudohalides [AgX′ (X′ = NCO or NCS)]. The tetraorgano compounds, R4M (M = Sn or Pb, and R = Ph or p-tolyl), and Bu3SnPh failed to react with IN3 and Bu3SnPhINCO but IN3 cleaved one tin-aryl bond from Ar4Sn in the presence of AlCl3. Addition of IN3 and INCO across the olefinic bond of Ph3SnCH2CHCH2 is preferred to tin-allyl bond cleavage. Reactions of hexaaryldileads with IN3 and INCO under appropriate conditions proceeded with the cleavage of a PbPb bond. Parallel reactions of cyanogen halides (CNI and CNBr) resulted in the formation of corresponding triaryllead halides and pseudohalide derivatives. 相似文献
In this paper, we present a model of potential energy surface for the H2O HCl system, consisting in the exact transformation of quantum chemical input data related to a minimal number of significant configurations. Both molecules are assumed as rigid. The interaction potential is given by an expansion in real spherical harmonics depending on the distance between the two centers of mass of the molecules and on four angles that define their mutual orientation. The main target of this work is the construction of a model of potential energy surface that requires a limited number of single energy points, which is suitable for applications to classical and quantum molecular dynamics simulations, permitting interpolation and further implementation of different sets of input data. 相似文献
Attachment of one electron to 1,2-diBeX-benzene and 1,2-diZnX-benzene derivatives leads to the formation of stronger Be Be and Zn Zn interaction compared to the neutral one. This is reflected in the dramatic shortening of the Be Be and Zn Zn distance. The formation of these 2-center-1-electron bonds have also been confirmed by topological survey of electron density using quantum theory of atoms in molecules and electron localization function. The formation of these bonds is expected to render stability to these radical anions. These radical anions are stable toward electron detachment and computed bond dissociation energy values are also significant. 相似文献
An sp 2 /sp 3 get‐together : A novel and efficient method can be used to synthesize 3,3‐disubstitued oxindoles by the direct intramolecular oxidative coupling of an aryl C? H and a C? H center (see scheme; DMF=N,N‐dimethylformamide).
In hydrogen‐metal‐phosphorus (H M P) transition metal complexes (proposed as intermediates of H P bond addition to alkynes in the catalytic hydrophosphorylation, hydrophosphinylation, and hydrophospination reactions), alkyne insertion into the metal‐hydrogen bond was found much more facile compared to alkyne insertion into the metal‐phosphorus bond. The conclusion was verified for different metals (Pd, Ni, Pt, and Rh), ligands, and phosphorus groups at various theory levels (B3LYP, B3PW91, BLYP, MP2, and ONIOM). The relative reactivity of the metal complexes in the reaction with alkynes was estimated and decreased in the order of Ni>Pd>Rh>Pt. A trend in relative reactivity was established for various types of phosphorus groups: PR2>P(O)R2>P(O)(OR)2, which showed a decrease in rate upon increasing the number of the oxygen atoms attached to the phosphorus center. 相似文献
A nanocomposite of Pd? TiO2? SiO2 is developed through a sol‐gel process from the reaction products of titanium isopropoxide followed by mixing the same with palladium linked 3‐glycidoxypropyltrimethoxysilane. The reaction product is sonicated and calcinated to obtain the nanocomposite of Pd? TiO2? SiO2. The calcination at 600 °C yielded an amorphous structure whereas at 900 °C it resulted into a nanocrystalline structure. The nanocomposite of palladium was further characterized by TEM, XRD, IR and EDS. The material acts as an efficient electrocatalyst. Electrocatalysis of ascorbic acid is observed at 0.1 V vs. Ag/AgCl, shows linearity between 1 µM and 1 mM in 0.1 M phosphate buffer (pH 7.0). 相似文献
We studied electronic structures and reactivity patterns of azo-compound I species (RN-Cpd I) by comparison to O-Cpd I of, e.g., cytochrome P450. The study shows that the RN-Cpd I species are capable of C=C aziridination and C-H amidation, in a two-state mechanism similar to that of O-Cpd I. However, unlike O-Cpd I, here the nitrogen substituent (R) exerts a major impact on structure and reactivity. Thus, it is demonstrated that Fe=NR bonds of RN-Cpd I will generally be substantially longer than Fe=O bonds; electron-withdrawing R groups will generate a very long Fe=N bond, whereas electron-releasing R groups should have the opposite effect and hence a shorter Fe=N bond. The R substituent controls also the reactivity of RN-Cpd I toward C=C and C-H bonds by exerting steric and electronic effects. Our analysis shows that an electron-releasing substituent will lower the barriers for both bond activation reactions, since the electronic factor makes the reactions highly exothermic, while an electron-withdrawing one should raise both barriers. The steric bulk of the substituent is predicted to inhibit more strongly the aziridination reactions. It is predicted that electron-releasing substituents with small bulk will create powerful aziridination reagents, whereas electron-withdrawing substituents like MeSO(2) will prefer C-H bond activation with preference that increases with steric bulk. Finally, the study predicts (i) that the reactions of RN-Cpd I will be less stereospecific than those of O-Cpd I and (ii) that aziridination will be more stereoselective than amidation. 相似文献