细胞色素P—450单加氧酶的模拟—在锰卟啉催化环己烷加氧反应中不同…

以ＭｎＴＰＰＣｌ为催化剂研究了不同氧原子供体ＰｈＩＯ，ＮａＯＣｌ和Ｈ２Ｏ２在环己烷加氧反应中的作用。根据动力学考察和ＵＶ－Ｖ１Ｓ，ＩＲ，ＥＳＲ分析认为，ＰｈＩＯ和ＮａＯＣｌ可能分别与ＮｔＰＰＣｌ形成具有转移氧原子能力的单核或双核的高氧化态氧化锰卟啉配合物，而Ｈ２Ｏ２与ＭｎＴＰＰＣｌ作用同形成非活性物种。     

μ－氧代双锰（Ⅲ）卟啉氧化反应及取代基效应研究

用紫外－可见光谱对氧化剂ＰｈＩＯ、Ｈ_２Ｏ_２和空气对μ－氧代双四苯基卟吩合锰（［ＴＰＰ·Ｍｎ（Ⅲ）］_２Ｏ）的氧化过程进行监测，揭示了［ＴＰＰＭｎ（Ⅲ）］_２Ｏ在不同氧化剂作用下具有不同的反应过程。研究了８种取代μ－氧双四苯基卟吩合锰｛［ＴＸＰＰＭｎ（Ⅲ）］_２Ｏ，Ｘ＝ｐ－（ｉ－Ｐｒ），ｐ－ＣＨ_３，ｐ－Ｃｌ，ｐ－Ｆ，ｐ－ＯＣＨ_３，Ｈ，ｍ－Ｃｌ，ｏ－Ｃｌ｝与Ｈ_２Ｏ_２反应中的取代基效应和溶剂效应。结果表明：上述反应为卟啉环上的吸电子基所促进；且反应速率随着反应溶剂的亲核性能的增加而增加。     

Na-W-Mn/SiO2催化剂活化甲烷的研究Ⅱ.活性氧物种

制备了不同Ｎａ、Ｗ、Ｍｎ组分的Ｎａ－Ｗ－Ｍｎ／ＳｉＯ２催化剂,并进行了Ｏ２程序升温脱附（Ｏ２－ＴＰＤ）和不同温度下Ｎａ－Ｗ－Ｍｎ／ＳｉＯ２催化剂的ＣＨ４脉冲反应（ＣＨ４－ＰＲ）。研究结果表明,Ｎａ－Ｗ－Ｍｎ／ＳｉＯ２催化剂活化甲烷的活笥氧物种是Ｗ和Ｍｎ提供的、高温下易于流动的表面晶格氧（Ｏ＾２－）。Ｎａ和Ｏ＾２－的活泼性具有重要的促进作用,它可以极化Ｗ、Ｍn的金属一氧键,促进Ｏ＾２－的流动性。Ｎａ     

金属键有机化合物的研究──非对称型η~5－取代环戊二烯基三羰基钼（钨）金属单键化合物的合成及表征

通过η５－Ｒ~１Ｃ＿５Ｈ＿４（ＣＯ）＿３ＭＮａ与η~５－Ｒ~２Ｃ＿５Ｈ＿４（ＣＯ）＿３ＭＮａ（Ｍ＝Ｍｏ，Ｗ）以及η~５－Ｒ~１Ｃ＿５Ｈ＿４（ＣＯ）＿３ＭｏＮａ与η~５－Ｒ~２Ｃ＿５Ｈ＿４（ＣＯ）＿３ＷＮａ在Ｆｅ＿２（ＳＯ＿４）＿３醋酸水溶液作用下的交叉氧化偶联反应，合成了７个新的非对称型金属单键化合物η~５－Ｒ~１Ｃ＿５Ｈ＿４（ＣＯ）－３Ｍｏ─Ｍｏ（ＣＯ）＿３Ｃ＿５Ｈ＿４Ｒ~２－η~５（Ｒ~１，Ｒ~２：Ｃ（Ｏ）Ｍｅ，ＣＯ２Ｅｔ），η５－Ｒ１Ｃ５Ｎ４（ＣＯ）３Ｗ─Ｗ（ＣＯ）３Ｃ５Ｈ４Ｒ２－η５（Ｒ１，Ｒ２：Ｃ（Ｏ）Ｍｅ，ＣＯ２Ｅｔ；Ｈ，ＣＯ２Ｅｔ）和η５－Ｒ１Ｃ５Ｈ４（ＣＯ）３Ｍｏ─Ｗ（ＣＯ）３Ｃ５Ｈ４Ｒ２－η５（Ｒ１，Ｒ２：Ｃ（Ｏ）Ｍｅ，Ｈ；Ｅｔ，Ｃ（Ｏ）Ｍｅ；Ｃ（Ｏ）Ｍｅ，ｎ－Ｂｕ；ＣＯ２Ｍｅ，ｎ－Ｂｕ）．用Ｃ／Ｎ分析、ＩＲ、１ＨＮＭＲ和ＭＳ表征了它们的结构，并对该氧化偶联反应的特点进行了讨论．     

混合三烃基锡有机酸酯化合物构效关系 （Ⅰ）二环己基－甲基－2，4－二溴－β－甲基苯氧乙酸锡酯 及二环己基－甲基－2－甲氧基－4－丙烯基苯氧乙酸锡酯的晶体结构和分子结构

报道２，４－Ｂｒ２Ｃ６Ｈ３ＯＣＨ（ＣＮ３）ＣＯ２Ｓｎ（Ｃ６Ｈ１１）２ＣＵ３（１）和２－ＯＣＨ３－４－ＣＨ３ＣＨ＝ＣＨＣ６Ｈ３ＯＣＨ２ＣＯ２Ｓｎ（Ｃ６Ｈ１１）２ＣＨ３（Ｈ２Ｏ）（Ⅱ）的晶体结构和分子结构。（Ⅰ）单斜晶系，空间群Ｐ２１／ｃ，ａ＝１３．０６７（３），ｂ＝１０．５９４（３），ｃ＝１８．１５７（４），β＝１０６．９９（２）°，Ｚ＝４，Ｄｃ＝１．６７２ｇ／ｃｍ３，Ｖ＝２４０３．７３，μ＝４３．７３１ｃｍ－１，Ｍｒ＝６２２．９９，Ｆ（０００）＝１２３２；（Ⅱ）单斜晶系，空间群Ｐ２１／ｎ，ａ＝１０．４０９（１），ｂ＝　１２．５７０（２），ｃ＝２０．６６４（２），β＝８３．５１（１）°，Ｚ＝４，Ｄｃ＝１．２８１ｇ／ｃｍ３，Ｖ＝２６８６．４Ａ３，μ＝９．７６１ｃｍ－１，Ｍｒ＝５３９．２８，Ｆ（０００）＝１１２０．最后的偏离因子，化合物（Ⅰ）Ｒ＝０．０４６，Ｒω＝０．０４６；化合物（Ⅱ）Ｒ＝０．０４９，Ｒω＝０．０４７。晶体结构解析表明，化合物（Ⅰ）和（Ⅱ）中的锡均被配体的３个碳和２个氧原子配位，配位原子呈畸变三角双锥构型；化合物中的环己基均为椅式构象；化合物（Ⅱ）中，配位水分子和另一分子的羰基氧与芳环上的甲基氧?     

双[N,N‘—1,2—亚乙基—2,2’—（苯基亚甲基）二（3,4—二甲基吡？…

首次报道了一个新的拟酶模型物－双［Ｎ，Ｎ＇－１，２－亚乙基－２，２＇－（苯基亚甲基）二（３，４－二甲基吡咯－５－醋缩亚胺）］合双锰的合成方法及光谱特征；并对用ＰｈＩＯ单加氧化环己烷反应的催化性能及自氧化反应进行了研究。结果表明，此Ｓｃｈｉｆｆ碱双锰配合物的催化性能及稳定性与金属卟啉ＴＰＰＭｎＣｌ相似。     

附加试剂及反应介质对TPPFeCl催化环己烷仿生氯化反应…

研究了某些附加试剂及反应介质对四苯基卟吩合铁（Ⅲ）［ＴＰＰＦｅＣｌ或（ＴＰＰＦｅ）２Ｏ］模拟细胞色素Ｐ－４５０催化ＰｈＩＯ羟化环己烷反应的影响。发现适量的异丙醇、吡啶及ＮａＯＨ能促进反应，加入盐酸及增大介质的极性对反应不利。证明了副产物环己酮主要是由ＰｈＩＯ直接氧化生产物环己醇生成的，ＴＰＰＦｅＣｌ的存在不利于酮的生成，醇的存在能延长催化剂的寿命。     

三(2-甲基-2-苯基丙基)锡羧酸酯的合成、结构表征和生物活性

苯丁锡（Ｔｏｒｇｕｅ［ＰｈＭｅ２ＣＣＨ２）３Ｓｎ］２Ｏ）是高效杀螨剂［１］,国内已实现工业化生产．为了寻找更好的有机锡杀螨剂新品种,人们曾对托尔克进行衍生化,合成了某些三（２－甲基－２－苯基丙基）锡芳氧乙酸酯［２］和某些长链羧酸及取代苯甲酸酯的衍生物［３］．本文拟合成系列新的三（２－甲基－２－苯基丙基）锡羧酸酯,并对目标化合物进行了结构表征和生物活性测定,反应式如下：（ＰｈＭｅ２ＣＣＨ２）３ＳｎＣｌ（１）ＮａＯＨ（２）ＲＣＯＯＨ（ＰｈＭｅ２ＣＣＨ２）３ＳｎＯ２ＣＲＲ＝ＣＨ３（１）,Ｃ２Ｈ５（２）…     

细胞色素P-450模拟酶的快速混合停流时间分辨吸收谱研究 Ⅱ.Mn~Ⅲ(Por.)Cl-PhIO体系

采用快速混合停流技术,考察了在实际反应条件下,不同锰卟啉配合物ＭｎⅢ（Ｐｏｒ．）Ｃｌ（Ｐｏｒ．＝ＴＰＰ、ＴＭＯＰＰ和ＴＦＰＰ）与单氧给体ＰｈＩＯ构建的细胞色素Ｐ－４５０模拟酶体系催化活性物种的生成及催化烯烃环氧化过程．在氧给体ＰｈＩＯ作用下,ＭｎⅢ（Ｐｏｒ．）Ｃｌ均生成了高价锰氧卟啉配合物和双核μ－氧锰卟啉配合物;但ＭｎⅢ（ＴＰＰ）Ｃｌ和ＭｎⅢ（ＴＭＯＰＰ）Ｃｌ存在严重的氧化分解,而ＭｎⅢ（ＴＦＰＰ）Ｃｌ不易氧化分解,且它的催化环氧化活性最高．     

合成气制低碳烯烃K－Fe－MnO／MgO催化剂的研究Ⅰ．MnO助剂的作用

采用ＣＯ加氢反应、ＣＯ－ＴＰＤ、ＣＯ／Ｈ＿２－ＴＰＳＲ及Ｃ＿２Ｈ＿４／Ｈ＿２－ＴＰＳＲ等手段，研究合成气制低碳烯烃反应Ｋ－Ｆｅ－ＭｎＯ／ＭｇＯ催化剂中ＭｎＯ的助剂作用。结果表明ＭｎＯ能大幅度提高低碳烯烃的选择性，尤其是乙烯的选择性；ＭｎＯ能抑制催化剂表面的乙烯加氢，因而有利于提高低碳烯烃的选择性及烯／烷的比值。     

Oxidation of cyclohexane by a high-valent iron bispidine complex: a combined experimental and computational mechanistic study

Experimental data suggest that there are various competing pathways for the catalytic and stoichiometric oxygenation of cyclohexane, assisted by iron-bispidine complexes and using various oxidants (H(2)O(2), O(2), PhIO). Density functional theory calculations indicate that both Fe(IV)=O and Fe(V)=O species are accessible and efficiently transfer their oxygen atoms to cyclohexane. The reactivities of the two isomers each and the two possible spin states for the Fe(IV)=O and Fe(V)=O species are sufficiently different to allow an interpretation of the experimental data.     

金属卟啉催化环己烷羟基化反应中环己酮的形成机理研究

单金属卟啉和双金属卟啉催化下PhIO常温氧化环己烷的羟基化反应中金属卟啉结构和反应溶剂、反应温度、反应时间等环境因素对产物酮含量及酮形成反应动力学的影响进行了系统研究, 并与金属卟啉催化下PhIO氧化环己醇的反应进行了对比, 提出了金属卟啉催化下环己烷羟基化反应中产物酮的形成机理。     

Syntheses of manganese and iron tetraspirobifluorene porphyrins as new catalysts for oxidation of alkenes by hydrogen peroxide and iodosylbenzene

The condensation of pyrrole with 9,9′-spirobifluorene aldehyde yields new the 5,10,15,20-tetra(spirobifluorene) porphyrins; epoxidation of cyclooctene and styrene derivatives catalyzed by the manganese and iron complexes is reported using H₂O₂ and PhIO as oxygen atom donors.     

Donor ligand effect on the nature of the oxygenating species in Mn(III)(salen)-catalyzed epoxidation of olefins: experimental evidence for multiple active oxidants

The stereoselectivity of olefin epoxidation catalyzed by Mn(III)(salen)X (1a, X = Cl(-); 1b, X = BF(4)(-)) complexes is examined in the presence of neutral donor ligands, employing various iodosylarenes (ArIO: PhIO, C(6)F(5)IO, and MesIO) as the oxygen atom source. The cis/trans ratios of stilbene oxides and the enantiomeric excesses of styrene oxide and 1,2-dihydronaphthalene oxide are found to be strongly dependent on the nature of the iodosylarenes under certain conditions. In other cases, olefin epoxidation is shown to proceed with essentially identical diastereoselectivities or enantioselectivities, regardless of the oxygen atom source used. We propose that a Mn(V)(salen)-oxo intermediate and a complex between the catalyst and the terminal oxidant competitively effect the epoxidation when the stereoselectivities are markedly dependent on the oxygen atom source. A single Mn(V)(salen)-oxo species is considered to be the sole oxygenating intermediate when the terminal oxidants do not exert a notable influence on the product selectivities. Our results clearly demonstrate the existence of multiple oxidizing species and the conditions in which only a single oxygenating intermediate is involved. The axial donor ligands (both anionic ligands and neutral ligands) are shown to strongly influence both the identity and the reactivity of the oxygenating species.     

N-h and N-C bond activation of pyrimidinic nucleobases and nucleosides promoted by an osmium polyhydride

Complex OsH(6)(P(i)Pr(3))(2) (1) reacts with 1-methylthymine and 1-methyluracil to give OsH(3)(P(i)Pr(3))(2)(nucleobase') (2, 3) containing the deprotonated nucleobases (nucleobase') κ(2)-N,O coordinated by the nitrogen atom at position 3 and the oxygen bonded to the carbon atom of the ring at position 4. Similarly, the reactions of 1 with thymidine, 5-methyluridine, deoxyuridine, and uridine lead to OsH(3)(P(i)Pr(3))(2)(nucleoside') (4-7) with the deprotonated nucleoside (nucleoside') κ(2)-N,O coordinated by the nitrogen atom at position 3 and the oxygen bonded to the carbon atom at position 4 of the nucleobases. Treatment of complexes 5 and 7, containing nucleosides derived from ribose, with OsH(2)Cl(2)(P(i)Pr(3))(2) (8) in the presence of Et(3)N affords dinuclear species OsH(3)(P(i)Pr(3))(2)(nucleobase')-(ribose)(P(i)Pr(3))(2)H(2)Os (9, 10) formed by two different metal fragments. Complex 1 also promotes the cleavage of the N-C bond of 2-7 to give the dinuclear species {OsH(3)(P(i)Pr(3))(2)}(2)(nucleobase') (11, 12) with the nucleobase skeleton (nucleobase') κ(2)-N,O coordinated to both metal fragments. These compounds can be also prepared by reaction of 1 with 0.5 equiv of thymine and uracil. The use of 1:1 hexahydride:nucleobase molar ratios gives rise to the preferred formation of the mononuclear complexes OsH(3)(P(i)Pr(3))(2)(nucleobase') (13, 14; nucleobase' = monodeprotonated thymine or uracil). The X-ray structures of complexes 6, 11, and 14 are also reported.     

Cerium(IV)-driven oxidation of water catalyzed by mononuclear ruthenium complexes

This paper reviews results from study of mononuclear ruthenium complexes capable of catalyzing the oxidation of water to molecular oxygen. These catalysts may be classified into three groups, with different rate laws associated with O₂ evolution. In one class, O₂ evolution proceeds via radical coupling of the oxygen atom of an Ru^V=O species with a hydroxocerium(IV) ion. O₂ evolution catalyzed by the second class occurs via acid–base reaction of the oxygen atom of an Ru^V=O species with a water molecule. In the third group, the dominant mechanism is oxo–oxo radical coupling between two Ru^V=O species. Several significant properties of the oxidant Ce(IV) are also discussed, including the singlet biradical character of the hydroxocerium(IV) ion.     

Luminescence and structural properties of lanthanide complexes of Schiff bases derived from pyridoxal and amino acids

Lanthanide complexes of Schiff bases (SBs) with 1:1 and 1:2 (M:Lig) stoichiometric ratios were prepared by condensation of pyridoxal (PL) and aspartic acid (Asp) or l-histidine (His), respectively, in the presence of the appropriate metal chloride as a templating agent. These complexes were studied by optical spectroscopy and single crystal X-ray diffraction techniques. Crystallographic studies of 1:1 ([Eu(PL-Asp)(H(2)O)(4)](H(2)O)) and 1:2 ([Eu(PL-His)(2)(H(2)O)(2)]Cl(H(2)O)(4)) complexes show that Eu(III) is eight-coordinate in both structures, in a distorted square antiprism environment formed by the phenolic oxygen of PL, the nitrogen atom of carbon-nitrogen double bond, oxygen atoms of the carboxylate groups of His or Asp, and oxygen atoms of the water molecules. The main species formed in aqueous solutions containing these SBs have been determined by analysis of the luminescence spectra, lifetimes of Eu(III) excited states and vibronic interaction as well as structural features of the Eu(III) coordination sphere. Possible tetradentate coordination function of SBs in aqueous solutions with relatively high concentrations as well as the potential application of the lanthanide SB complexes as new luminescence materials are discussed.     

Effects of a single water molecule on the OH + H2O2 reaction

The effect of a single water molecule on the reaction between H(2)O(2) and HO has been investigated by employing MP2 and CCSD(T) theoretical approaches in connection with the aug-cc-PVDZ, aug-cc-PVTZ, and aug-cc-PVQZ basis sets and extrapolation to an ∞ basis set. The reaction without water has two elementary reaction paths that differ from each other in the orientation of the hydrogen atom of the hydroxyl radical moiety. Our computed rate constant, at 298 K, is 1.56 × 10(-12) cm(3) molecule(-1) s(-1), in excellent agreement with the suggested value by the NASA/JPL evaluation. The influence of water vapor has been investigated by considering either that H(2)O(2) first forms a complex with water that reacts with hydroxyl radical or that H(2)O(2) reacts with a previously formed H(2)O·OH complex. With the addition of water, the reaction mechanism becomes much more complex, yielding four different reaction paths. Two pathways do not undergo the oxidation reaction but an exchange reaction where there is an interchange between H(2)O(2)·H(2)O and H(2)O·OH complexes. The other two pathways oxidize H(2)O(2), with a computed total rate constant of 4.09 × 10(-12) cm(3) molecule(-1) s(-1) at 298 K, 2.6 times the value of the rate constant of the unassisted reaction. However, the true effect of water vapor requires taking into account the concentration of the prereactive bimolecular complex, namely, H(2)O(2)·H(2)O. With this consideration, water can actually slow down the oxidation of H(2)O(2) by OH between 1840 and 20.5 times in the 240-425 K temperature range. This is an example that demonstrates how water could be a catalyst in an atmospheric reaction in the laboratory but is slow under atmospheric conditions.     

Synthesis, structure, and catalytic activity of mononuclear iron and (mu-Oxo)diiron complexes with the ligand 2,6-bis(N-methylbenzimidazol-2-yl)pyridine

Iron complexes including polyimidazole and exchangeable ligands are studied with the aim of modeling the structural and functional features of the non-heme iron centers of dinuclear proteins, such as methane monooxygenase. In [Fe(2)OL(2)(MeOH)(2)(NO(3))(2)](NO(3))(2) (1) (L = 2,6-bis(N-methylbenzimidazol-2-yl)pyridine), each Fe(III) is in a distorted octahedral environment and has a donor set of N(3)O(3) which includes three N atoms from L and three O atoms from a nitrate, micro-oxo, and methanol. In complex [FeLCl(3)] (2) (L = 2,6-bis(N-methylbenzimidazol-2-yl)pyridine), Fe(III) is coordinated to three nitrogen atoms from L and three chloride ions. Complex 1 efficiently catalyzed the oxidation of cyclohexane with 51% conversion to cyclohexanol. It also catalyzed the epoxidation of styrene, cyclohexane, 2-methyl-2-butene, and cis- and trans-2-heptene with 51-84% conversions and high selectivity (71-99%) for epoxide products. Complex 2, however, has no specific reactivity toward these substrates. From the alcohol/ketone (A/K) ratio close to 1 in the oxidation of cyclohexane, the low KIE (kinetic isotope effect K(H)/K(D) ratio = 1.8) for cyclohexanol formation, and the nonstereospecificity of the oxidation of cis-dimethylcyclohexane, it can be concluded that long-lived alkyl radicals are involved in the oxidation catalyzed by complex 1. On the other hand, the stereospecific epoxidation of alkenes, the stereoselective oxidation of cumene, and the high degree of retention of configuration in the oxidation of cis- and trans-2-heptene suggest that a nonradical species, probably a metal-based intermediate, is involved in the oxidation of alkenes and cumene.     

附加试剂及反应介质对TPPFeCl催化环己烷仿生氧化反应性能的影响

研究了某些附加试剂及反应介质对四苯基卟吩合铁(Ⅲ)[TPPFeCl或(TPPFe)₂O]模拟细胞色素P-450催化PhIO羟化环己烷反应的影响。发现适量的异丙醇、吡啶及NaOH能促进反应,加入盐酸及增大介质的极性对反应不利。证明了副产物环己酮主要是由PhIO直接氧化主产物环己醇生成的,TPPFeCl的存在不利于酮的生成,醇的存在能延长催化剂的寿命。