首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 78 毫秒
1.
Low‐valent osmium nitrides are discussed as intermediates in nitrogen fixation schemes. However, rational synthetic routes that lead to isolable examples are currently unknown. Here, the synthesis of the square‐planar osmium(IV) nitride [OsN(PNP)] (PNP=N(CH2CH2P(tBu)2)2) is reported upon reversible deprotonation of osmium(VI) hydride [Os(N)H(PNP)]+. The OsIV complex shows ambiphilic nitride reactivity with SiMe3Br and PMe3, respectively. Importantly, the hydrogenolysis with H2 gives ammonia and the polyhydride complex [OsH4(HPNP)] in 80 % yield. Hence, our results directly demonstrate the role of low‐valent osmium nitrides and of heterolytic H2 activation for ammonia synthesis with H2 under basic conditions.  相似文献   

2.
The catalytic systems [(BPMEN)FeII(CH3CN)2](ClO4)2/H2O2/CH3OOH and [(TPA)FeII(CH3CN)2](ClO4)2/H2O2/CH3OOH, where BPMEN = N,N′-dimethyl-N,N′-bis(2-pyridylmethyl)-1,2-diaminoethane and TPA = tris(2-pyridylmethyl)amine, provide selective olefin epoxidation. Proton NMR studies showed that the mononuclear iron(IV) oxo complexes [(L)FeIV=O]2+, with L = BPMEN or TPA, are present in the cited catalytic systems. These intermediates are the decomposition products of the acylperoxo complexes [(L)FeIII-O3CCH3]2+. Such a complex was observed by the 2H NMR technique at low temperatures. The [(L)FeIV=O]2+ and [(L)FeV=O]3+ oxo complexes are possible active species in the studied catalytic systems.  相似文献   

3.
The trinuclear osmium carbonyl cluster, [Os3(CO)10(MeCN)2], is allowed to react with 1 equiv. of [IrCp1Cl2]2 (Cp1 = pentamethylcyclopentadiene) in refluxing dichloromethane to give two new osmium–iridium mixed-metal clusters, [Os3Ir2(Cp1)2(μ-OH)(μ-CO)2(CO)8Cl] (1) and [Os3IrCp1(μ-OH)(CO)10Cl] (2), in moderate yields. In the presence of a pyridyl ligand, [C5H3N(NH2)Br], however, the products isolated are different. Two osmium–iridium clusters with different coordination modes of the pyridyl ligand are afforded, [Os3IrCp1(μ-H)(μ-Cl)(η33-C5H2N(NH2)Br)(CO)9] (3) and [Os3IrCp1(μ-Cl)223-C5H3N(NH)Br)(CO)7] (4). All of the new compounds are characterized by conventional spectroscopic methods, and their structures are determined by single-crystal X-ray diffraction analysis.  相似文献   

4.
The clectrochemical behaviour of the complexes [RuII(L)(CO)2Cl2], [RuII(L)(CO)Cl3][Me4N] and [RuII(L)(CO)2(CH3CN)2][CF3SO3]2 (L = 2,2′-bipyridine or 4,4′-isopropoxycarbonyl-2,2′-bipyridine) has been investigated in CH3CN. The oxidation of [Ru(L)(CO)2Cl2] produces new complexes [RuIII(L)(CO)(CH3CN)2Cl]2+ as a consequence of the instability of the electrogenerated transient RuIII species [RuIII(L)(CO)2Cl2]+. In contrast, the oxidation of [RuII(L)(CO)Cl3][Me4N] produces the stable [RuIII(L)(CO)Cl3] complex. In contrast [RuII(L)(CO)2(CH3CN)2][CF3SO3]2 is not oxidized in the range up to the most positive potentials achievable. The reduction of [RuII(L)(CO)2Cl2] and [RuII(L)(CO)2(CH3CN)2][CF3SO3]2 results in the formation of identical dark blue strongly adherent electroactive films. These films exhibit the characteristics of a metal-metal bond dimer structure. No films are obtained on reduction of [RuII(L)(CO)Cl3][Me4N]. The effect of the substitution of the bipyridine ligand by electron-withdrawing carboxy ester groups on the electrochemical behaviour of all these complexes has also been investigated.  相似文献   

5.
Heme and nonheme-type flavone synthase enzymes, FS I and FS II are responsible for the synthesis of flavones, which play an important role in various biological processes, and have a wide range of biomedicinal properties including antitumor, antimalarial, and antioxidant activities. To get more insight into the mechanism of this curious enzyme reaction, nonheme structural and functional models were carried out by the use of mononuclear iron, [FeII(CDA-BPA*)]2+ (6) [CDA-BPA = N,N,N’,N’-tetrakis-(2-pyridylmethyl)-cyclohexanediamine], [FeII(CDA-BQA*)]2+ (5) [CDA-BQA = N,N,N’,N’-tetrakis-(2-quinolilmethyl)-cyclohexanediamine], [FeII(Bn-TPEN)(CH3CN)]2+ (3) [Bn-TPEN = N-benzyl-N,N’,N’-tris(2-pyridylmethyl)-1,2-diaminoethane], [FeIV(O)(Bn-TPEN)]2+ (9), and manganese, [MnII(N4Py*)(CH3CN)]2+ (2) [N4Py* = N,N-bis(2-pyridylmethyl)-1,2-di(2-pyridyl)ethylamine)], [MnII(Bn-TPEN)(CH3CN)]2+ (4) complexes as catalysts, where the possible reactive intermediates, high-valent FeIV(O) and MnIV(O) are known and well characterised. The results of the catalytic and stoichiometric reactions showed that the ligand framework and the nature of the metal cofactor significantly influenced the reactivity of the catalyst and its intermediate. Comparing the reactions of [FeIV(O)(Bn-TPEN)]2+ (9) and [MnIV(O)(Bn-TPEN)]2+ (10) towards flavanone under the same conditions, a 3.5-fold difference in reaction rate was observed in favor of iron, and this value is three orders of magnitude higher than was observed for the previously published [FeIV(O)(N2Py2Q*)]2+ [N,N-bis(2-quinolylmethyl)-1,2-di(2-pyridyl)ethylamine] species.  相似文献   

6.
Abstract

New dinuclear asymmetric complexes of ruthenium and rhenium, of formula [(bpy)(CO)3 ReI(4,4′-bpy)RuII/III(NH3)5]3+/4+ have been prepared and characterized by spectroscopic and electrochemical techniques. In the mixed-valent species [ReI, RuIII], the back electron transfer reaction RuII → ReII, that occurs after light excitation, is predicted to be in the Marcus inverted region. This fact is consistent with the observed quenching of the luminiscence of the Re chromophore in [(bpy)(CO)3ReI(4,4′-bpy)RuIII(NH3)5]4+, when compared to the parent complex [(bpy)(CO)3ReI(4,4′-bpy)]+. A theoretical treatment due to Creutz, Newton and Sutin has been successfully applied to predict the electronic coupling element in the mixed-valent complex.  相似文献   

7.
The use of the [FeIII(AA)(CN)4]? complex anion as metalloligand towards the preformed [CuII(valpn)LnIII]3+ or [NiII(valpn)LnIII]3+ heterometallic complex cations (AA=2,2′‐bipyridine (bipy) and 1,10‐phenathroline (phen); H2valpn=1,3‐propanediyl‐bis(2‐iminomethylene‐6‐methoxyphenol)) allowed the preparation of two families of heterotrimetallic complexes: three isostructural 1D coordination polymers of general formula {[CuII(valpn)LnIII(H2O)3(μ‐NC)2FeIII(phen)(CN)2 {(μ‐NC)FeIII(phen)(CN)3}]NO3 ? 7 H2O}n (Ln=Gd ( 1 ), Tb ( 2 ), and Dy ( 3 )) and the trinuclear complex [CuII(valpn)LaIII(OH2)3(O2NO)(μ‐NC)FeIII(phen)(CN)3] ? NO3 ? H2O ? CH3CN ( 4 ) were obtained with the [CuII(valpn)LnIII]3+ assembling unit, whereas three isostructural heterotrimetallic 2D networks, {[NiII(valpn)LnIII(ONO2)2(H2O)(μ‐NC)3FeIII(bipy)(CN)] ? 2 H2O ? 2 CH3CN}n (Ln=Gd ( 5 ), Tb ( 6 ), and Dy ( 7 )) resulted with the related [NiII(valpn)LnIII]3+ precursor. The crystal structure of compound 4 consists of discrete heterotrimetallic complex cations, [CuII(valpn)LaIII(OH2)3(O2NO)(μ‐NC)FeIII(phen)(CN)3]+, nitrate counterions, and non‐coordinate water and acetonitrile molecules. The heteroleptic {FeIII(bipy)(CN)4} moiety in 5 – 7 acts as a tris‐monodentate ligand towards three {NiII(valpn)LnIII} binuclear nodes leading to heterotrimetallic 2D networks. The ferromagnetic interaction through the diphenoxo bridge in the CuII?LnIII ( 1 – 3 ) and NiII?LnIII ( 5 – 7 ) units, as well as through the single cyanide bridge between the FeIII and either NiII ( 5 – 7 ) or CuII ( 4 ) account for the overall ferromagnetic behavior observed in 1 – 7 . DFT‐type calculations were performed to substantiate the magnetic interactions in 1 , 4 , and 5 . Interestingly, compound 6 exhibits slow relaxation of the magnetization with maxima of the out‐of‐phase ac signals below 4.0 K in the lack of a dc field, the values of the pre‐exponential factor (τo) and energy barrier (Ea) through the Arrhenius equation being 2.0×10?12 s and 29.1 cm?1, respectively. In the case of 7 , the ferromagnetic interactions through the double phenoxo (NiII–DyIII) and single cyanide (FeIII–NiII) pathways are masked by the depopulation of the Stark levels of the DyIII ion, this feature most likely accounting for the continuous decrease of χM T upon cooling observed for this last compound.  相似文献   

8.
Rh‐containing metallacycles, [(TPA)RhIII2‐(C,N)‐CH2CH2(NR)2‐]Cl; TPA=N,N,N,N‐tris(2‐pyridylmethyl)amine have been accessed through treatment of the RhI ethylene complex, [(TPA)Rh(η2CH2CH2)]Cl ([ 1 ]Cl) with substituted diazenes. We show this methodology to be tolerant of electron‐deficient azo compounds including azo diesters (RCO2N?NCO2R; R=Et [ 3 ]Cl, R=iPr [ 4 ]Cl, R=tBu [ 5 ]Cl, and R=Bn [ 6 ]Cl) and a cyclic azo diamide: 4‐phenyl‐1,2,4‐triazole‐3,5‐dione (PTAD), [ 7 ]Cl. The latter complex features two ortho‐fused ring systems and constitutes the first 3‐rhoda‐1,2‐diazabicyclo[3.3.0]octane. Preliminary evidence suggests that these complexes result from N–N coordination followed by insertion of ethylene into a [Rh]?N bond. In terms of reactivity, [ 3 ]Cl and [ 4 ]Cl successfully undergo ring‐opening using p‐toluenesulfonic acid, affording the Rh chlorides, [(TPA)RhIII(Cl)(κ1‐(C)‐CH2CH2(NCO2R)(NHCO2R)]OTs; [ 13 ]OTs and [ 14 ]OTs. Deprotection of [ 5 ]Cl using trifluoroacetic acid was also found to give an ethyl substituted, end‐on coordinated diazene [(TPA)RhIII2‐(C,N)‐CH2CH2(NH)2‐]+ [ 16 ]Cl, a hitherto unreported motif. Treatment of [ 16 ]Cl with acetyl chloride resulted in the bisacetylated adduct [(TPA)RhIII2‐(C,N)‐CH2CH2(NAc)2‐]+, [ 17 ]Cl. Treatment of [ 1 ]Cl with AcN?NAc did not give the Rh?N insertion product, but instead the N,O‐chelated complex [(TPA)RhI ( κ2‐(O,N)‐CH3(CO)(NH)(N?C(CH3)(OCH?CH2))]Cl [ 23 ]Cl, presumably through insertion of ethylene into a [Rh]?O bond.  相似文献   

9.
The catalytic chemosensing assay (CCA), a new indicator displacement assay, was developed for selective detection of methomyl, a highly toxic pesticide. Trimetallic complex {[FeII(dmbpy)(CN)4]-[PtII(DMSO)Cl]2-[RuII(bpy)2(CN)2]} ( 1 ; dmbpy=4,4′-dimethyl-2,2′-bipyridine, bpy=2,2′-bipyridine) was synthesized as a task-specific catalyst to initially reduce and degrade methomyl to CH3SH/CH3NH2/CH3CN/CO2. The thus-produced CH3SH interacts with the trimetallic complex to displace the cis-[RuII(bpy)2(CN)2] luminophore for monitoring. Other pesticides, including organophosphates and similar carbamate pesticides, remained intact under the same catalytic conditions; a selective sensing signal is only activated when 1 recognizes methomyl. Furthermore, 1 can be applied to detect methomyl in real water samples. In the luminescent mode of the assay, the method detection limit (MDL) of 1 for methomyl (LD50=17 mg kg−1) was 1.12 mg L−1.  相似文献   

10.
α-Si3N4 is synthesized by an ammonia thermal synthesis using a cyclic oligosilazane, [(CH3)2SiNH]4, as the starting material. [(CH3)2SiNH]4 reacts in the presence of ammonia at 900°C and 80 MPa pressure to give silicon nitride imide (Si2N2NH). Subsequently, Si2N2NH is converted into α-Si3N4 by thermal decomposition at 1500°C and 0.1 MPa nitrogen with the simultaneous loss of NH3.  相似文献   

11.
Reactions of trinickel complex of tripodal tris‐tacn ligand N(CH2m‐C6H4‐CH2tacn)3 ( L , tacn=1,4,7‐triazacyclononane) in acetonitrile–methanol solution with and without phosphate led to two complexes of distinct nuclearities, [(NiIICl)3(CH3OH)3(HPO4) L ](PF6) (Ni3, 1 ) and [(NiII5(CN)4(H2O)8Cl)6 L 8]Cl30 (Ni30, 2 ). Ligand L takes upward and downward conformation in the structure of 1 and 2 , respectively. It is proposed that phosphate directs the upward conformation of Ni3 L to form 1 . In the absence of phosphate, Ni3 L assembles with cyanide ions, which are formed by Ni‐catalyzed C?CN bond cleavage of acetonitrile, to give a nano‐sized Ni30 cage. Complex 2 represents a discrete truncated octahedron cage assembled with [Ni5(CN)4]6+ squares and large and flexible triangular ligands, which is scarcely observed for self‐assembled metal‐organic cages. The magnetic properties of 1 and 2 were examined, showing intriguing magnetic properties.  相似文献   

12.
The preparation and X‐ray crystal structure analysis of {trans‐[Pt(MeNH2)2(9‐MeG‐N1)2]} ? {3 K2[Pt(CN)4]} ? 6 H2O ( 3 a ) (with 9‐MeG being the anion of 9‐methylguanine, 9‐MeGH) are reported. The title compound was obtained by treating [Pt(dien)(9‐MeGH‐N7)]2+ ( 1 ; dien=diethylenetriamine) with trans‐[Pt(MeNH2)2(H2O)2]2+ at pH 9.6, 60 °C, and subsequent removal of the [(dien)PtII] entities by treatment with an excess amount of KCN, which converts the latter to [Pt(CN)4]2?. Cocrystallization of K2[Pt(CN)4] with trans‐[Pt(MeNH2)2(9‐MeG‐N1)2] is a consequence of the increase in basicity of the guanine ligand following its deprotonation and Pt coordination at N1. This increase in basicity is reflected in the pKa values of trans‐[Pt(MeNH2)2(9‐MeGH‐N1)2]2+ (4.4±0.1 and 3.3±0.4). The crystal structure of 3 a reveals rare (N7,O6 chelate) and unconventional (N2,C2,N3) binding patterns of K+ to the guaninato ligands. DFT calculations confirm that K+ binding to the sugar edge of guanine for a N1‐platinated guanine anion is a realistic option, thus ruling against a simple packing effect in the solid‐state structure of 3 a . The linkage isomer of 3 a , trans‐[Pt(MeNH2)2(9‐MeG‐N7)2] ( 6 a ) has likewise been isolated, and its acid–base properties determined. Compound 6 a is more basic than 3 a by more than 4 log units. Binding of metal entities to the N7 positions of 9‐MeG in 3 a has been studied in detail for [(NH3)3PtII], trans‐[(NH3)2PtII], and [(en)PdII] (en=ethylenediamine) by using 1H NMR spectroscopy. Without exception, binding of the second metal takes place at N7, but formation of a molecular guanine square with trans‐[(Me2NH2)PtII] cross‐linking N1 positions and trans‐[(NH3)2PtII] cross‐linking N7 positions could not be confirmed unambiguously, despite the fact that calculations are fully consistent with its existence.  相似文献   

13.
Os3(CO)12 catalyses the conversion of NMe2Ph to (4-NMe2C6H4)2CH2 and NHMePh in refluxing N,N-dimethylaniline. This reaction is similarly catalysed by H4Os4(CO)12, while (4-NHMeC6H4)2CH2 may be obtained from NHMePh. In this case, however, NMe2Ph and NH2Ph are also formed, and after longer reaction times mixed products of type (4-NRR′C6H4)2CH2 (R or R′ = H or Me) are obtained. The formation of H3Os3(CH)(CO)9 indicates methyl transfer from nitrogen to osmium which may be a key step in the catalysis, but it does not appear that clusters are essential since Fe(CO)5 and Cr(CO)6 are also weakly active.  相似文献   

14.
The spiked triangular triosmium-platinum cluster complex Os3Pt(μ-H)(μ42-CCPh)(CO)10(PCy3) has been synthesised by treatment of the unsaturated Os3Pt(μ-H)2(CO)10(PCy3) with LiCCPh followed by protonation. Crystallographic analysis reveals an unusual twisted configuration of the μ42-CCPh ligand about the triosmium framework such that the complex may be regarded as a platina-allenyl moiety coordinated to an Os3(μ-H)(CO)9 unit.  相似文献   

15.
Reaction of [K(DME)][Th{N(R)(SiMe2CH2)}2(NR2)] (R = SiMe3) with 1 equiv. of [U(NR2)3(NH2)] (1) in THF, in the presence of 18-crown-6, results in formation of a bridged uranium–thorium nitride complex, [K(18-crown-6)(THF)2][(NR2)3UIV(μ-N)ThIV(NR2)3] (2), which can be isolated in 48% yield after work-up. Complex 2 is the first isolable molecular mixed-actinide nitride complex. Also formed in the reaction is the methylene-bridged mixed-actinide nitride, [K(18-crown-6)][K(18-crown-6)(Et2O)2][(NR2)2U(μ-N)(μ–κ2-C,N–CH2SiMe2NR)Th(NR2)2]2 (3), which can be isolated in 34% yield after work-up. Complex 3 is likely generated by deprotonation of a methyl group in 2 by [NR2], yielding the new μ-CH2 moiety and HNR2. Reaction of 2 with 0.5 equiv. of I2 results in formation of a UV/ThIV bridged nitride, [(NR2)3UV(μ-N)ThIV(NR2)3] (4), which can be isolated in 42% yield after work-up. The electronic structure of 4 was analyzed with EPR spectroscopy, SQUID magnetometry, and NIR-visible spectroscopy. This analysis demonstrated that the energies of 5f orbitals of 4 are largely determined by the strong ligand field exerted by the nitride ligand.

The heterobimetallic actinide nitride [(NR2)3UV(μ-N)ThIV(NR2)3] (R = SiMe3) has an mJ = 5/2 ground state and its highest energy 5f excited state is primarily 5f-Nnitride σ-antibonding in character.  相似文献   

16.
Two new platinum-triosmium cluster complexes PtOs3(CO)9(COD)(μ4-FcC4Fc) (4) and Pt2Os3(CO)10(COD)(μ5-FcC4Fc) (5) containing the electroactive 1,4-bis-ferrocenylbutadiyne ligand FcC4Fc were obtained from the reaction of Os3(CO)103-FcC4Fc) (3) with Pt(COD)2. Compounds 4 and 5 were characterized by IR and 1H-NMR spectroscopy, by single crystal X-ray diffraction analysis and by differential pulse voltammetry. Compound 4 consists of a butterfly cluster of one platinum and three osmium atoms with the platinum atom in one of the wing-tip positions. The cluster is co-ordinated to one of the C---C triple bonds of the FcC4Fc ligand in the μ4-bonding mode. Cluster 5 exhibits the bow tie structure for five metal atoms: two of platinum and three of osmium. Both triple bonds of the butadiyne ligand are co-ordinated in this complex. Both products show two one electron oxidations for the ferrocenyl groups: for 4 at E°=+0.356 and +0.503 V versus Ag AgCl, and for 5 at E°=+0.478 and +0.576 V.  相似文献   

17.
A prolonged storage of a solution of RhCl3·nH2O in N,N-dimethylformamide (DMF) at room temperature is attended by the consecutive formation of two precipitates, which mainly contain the [(CH3)2NH2][RhCl5(DMF)] complex (I) and the complex [RhCl3(DMF)3] (II) liberates. The addition of PPh4Cl to an aqueous solution of complex I brings about the precipitation of [PPh4][RhCl4(H2O)2] (III). Complex II (a mixture of mer-and fac-isomers) can be obtained also by treatment of [RhCl3(CH3CN)3] with DMF. In the course of the latter reaction, the formation of intermediate complex [RhCl3(CH3CN)2(DMF)] (IV) is observed. Complexes I–IV are characterized by elemental analysis; complexes I, II, and IV are characterized by the IR and 1H and 13C NMR spectra. The structures of III and IV are determined by X-ray diffraction analysis.  相似文献   

18.
The phosphino-substituted sulphur diimide, S(NPtBu2)2, reacts with the trinuclear osmium clusters Os3(CO)11(NCMe) and H2Os3(CO)10 with cleavage of one of the NS bonds to give the cluster compounds Os3(CO)11[PtBu2(NH2)] (I) and HOs3(CO)9[PtBu2N(H)S] (II), respectively. In the solid state, I contains a closed Os3 triangle with the phosphine ligand bonded equatorially to an osmium atom through the phosphorus. In solution intramolecular dynamic processes are observed which are explained by carbonyl migration and pseudoration mechanisms. The osmium cluster II, in the solid state, forms an irregular Os3 triangle which is bridged by a [PtBu2N(H)S] system, and the longest edge of which is bridged by a μ2-hydride. In contrast to I, molecule II is relatively rigid in solution; only pseudorotations are observed as dynamic phenomena.  相似文献   

19.
Abstract

In the mixed-valence complex [RuIII(NH3)5(μ-dpypn)FeII(CN)5] with the flexible bridging ligand 1,3-di(4-pyridyl)propane (dpypn), electrostatic interactions between the {Ru(NH3)5}3+ and {Fe(CN)5}3? moieties drive a strong bending of dpypn and approximation of the RuIII and FeII centers, from which the enhanced electronic coupling between metal ions produces an intense intervalence-transfer absorption in the near-infrared region. Density functional theory calculations corroborate both the electrostatic bending in this heterobinuclear complex and a linear geometry in the homobinuclear counterparts [Ru(NH3)5(μ-dpypn)Ru(NH3)5]5+ and [Fe(CN)5(μ-dpypn)Fe(CN)5]5?, for which no evidence of electronic coupling was found because of the separation between metal centers. Furthermore, the heterobinuclear species formed an inclusion complex with β-cyclodextrin where the imposed linear geometry prevents significant electronic coupling and intervalence charge transfer between the RuIII and FeII centers.  相似文献   

20.
Oxoiron(IV) complexes bearing tetradentate ligands have been extensively studied as models for the active oxidants in non-heme iron-dependent enzymes. These species are commonly generated by oxidation of their ferrous precursors. The mechanisms of these reactions have seldom been investigated. In this work, the reaction kinetics of complexes [FeII(CH3CN)2L](SbF6)2 ( [1](SbF6)2 and [2](SbF6)2 ) and [FeII(CF3SO3)2L] ( [1](OTf)2 and [2](OTf)2 ( 1 , L=Me,HPytacn; 2 , L=nP,HPytacn; R,R′Pytacn=1-[(6-R′-2-pyridyl)methyl]-4,7- di-R-1,4,7-triazacyclononane) with Bu4NIO4 to form the corresponding [FeIV(O)(CH3CN)L]2+ ( 3 , L=Me,HPytacn; 4 , L=nP,HPytacn) species was studied in acetonitrile/acetone at low temperatures. The reactions occur in a single kinetic step with activation parameters independent of the nature of the anion and similar to those obtained for the substitution reaction with Cl as entering ligand, which indicates that formation of [FeIV(O)(CH3CN)L]2+ is kinetically controlled by substitution in the starting complex to form [FeII(IO4)(CH3CN)L]+ intermediates that are converted rapidly to oxo complexes 3 and 4 . The kinetics of the reaction is strongly dependent on the spin state of the starting complex. A detailed analysis of the magnetic susceptibility and kinetic data for the triflate complexes reveals that the experimental values of the activation parameters for both complexes are the result of partial compensation of the contributions from the thermodynamic parameters for the spin-crossover equilibrium and the activation parameters for substitution. The observation of these opposite and compensating effects by modifying the steric hindrance at the ligand illustrates so far unconsidered factors governing the mechanism of oxygen atom transfer leading to high-valent iron oxo species.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号