铜配合物修饰的钼氧簇超分子化合物催化烯烃环氧化（英文）

近年来,含有过渡金属配合物和多金属氧酸盐的三维超分子化合物的合成与性能研究受到广泛关注.利用过渡金属配合物优良的可裁剪性和修饰性,可以对多金属氧酸盐化合物的结构和性质进行有效调控,进而构造出具有独特空间结构和性质的新型功能材料.这类材料往往具有多金属氧酸盐与过渡金属配合物两者结合的优点,在医学、光学、磁性材料、气体吸附材料及催化等领域显示出重要的学术研究价值和潜在的应用前景.然而,相比于在化合物合成及结构研究领域中的快速发展,过渡金属配合物修饰的多金属氧酸盐基化合物在催化领域中应用较少.本文采用水热合成法,以4,4′-联吡啶(bipy)或1,4′-双咪唑-1-甲基苯(bix)为氮杂环配体,合成了两个铜配合物修饰的钼氧簇超分子化合物催化剂,分别记为[Cu(bipy)]4[Mo15O47]·2H2O(1)和[Cu(bix)][(Cubix)(δ-Mo8O26)0.5](2).催化剂1中包含一个由铜的4,4′-联吡啶有机链修饰的钼氧簇链,催化剂2是由1,4′-双咪唑-1-甲基苯有机配体、铜离子和八钼酸盐构筑的具有自穿插结构的超分子化合物.通过以叔丁基过氧化氢为氧化剂的烯烃环氧化催化反应,考察了两种催化剂的催化性能.结果表明,催化剂1和2对环辛烯或1-辛烯环氧化反应表现出较高的催化活性,性能均明显优于未引入铜配合物的超分子化合物(H2bix)[(Hbix)2(γ-Mo8O26)]2·H2O(3);在相同反应条件下,催化剂1表现出更高的催化活性;溶剂种类显著影响催化剂的催化性能,以乙腈为溶剂时,苯乙烯环氧化反应主产物为苯甲醛(仅有很少量的环氧化合物),而以氯仿为溶剂时,环氧化合物选择性显著提高;中断实验和循环测试结果表明,催化剂1和2在1-辛烯环氧化反应中均表现出良好的稳定性和循环使用性.FT-IR和XRD表征结果证实,经多次循环使用后催化剂结构基本保持不变,表明催化剂具有良好的结构稳定性.XPS表征结果表明,催化剂1中钼的正电性高于催化剂2,这是由于配体类型不同及钼氧簇结构不同所致.拥有较高正电性的钼物种通常会表现出更高的催化烯烃环氧化反应能力,这可能是催化剂1的催化活性优于催化剂2的主要原因.此外,通过结构分析可以看出,催化剂1具有更开放的框架结构,这更有利于反应物扩散,继而使催化剂表现出更高的催化活性.需要指出的是,催化剂1和2中存在的铜配合物也可能直接作为新的活性中心参与对氧化剂的活化,继而对催化剂性能(活性和选择性)产生影响;此外,铜配合物与钼氧簇之间较强的相互作用使所形成的超分子化合物具有良好的结构稳定性,继而使这类超分子化合物催化剂表现出较为优异的稳定性和循环使用性.     

膦化聚苯乙烯担载四核羰基钴簇的合成和催化作用

合成了两种含膦聚苯乙烯载体和此二载体与四核羰基钴簇CO_4(CO)_8(μ_2-CO_2(μ_4-PPh)_2通过配体交换反应,合成两种担载的金属原子簇催化剂.用IR、VU-DRS和XPS表征担载簇配合物的结构.考察了担载簇催化剂对讣茑烯烃的氢甲酰化反应的催化活性.其活性顺序为:1-庚烯>环己烯>二异丁烯>2-辛烯>苯乙烯.     

金属离子在液相氧化中的催化作用——Ⅹ.过渡金属氯化物与简单配体原位形成的配合物在环己烯氧化反应中的催化作用

本文研究了由过渡金属氯化物(MnCl_2、FeCl_2、CoCl_2、CuCl)与2,2′-二吡啶原位形成的配合物,在环己烯氧化反应中的催化性能以及配体性质对所形成的配合物催化性能的影响.结果表明,多种过渡金属氯化物可与2,2′-二吡啶原位形成有催化活性的配合物,其催化活性与金属离子性质、形成配合物能力以及配体性质有关.     

一种新型钼钒酸盐的合成、结构和磁性表征

用水热方法合成了一个新型的钼钒多金属氧酸盐[PⅤMoⅥ7MoⅤVⅣ8O44][Ni(Phen)2OH]4·3H2O(1),用元素分析、红外光谱和X射线单晶衍射等技术手段对化合物的晶体结构进行了表征。结果表明,该化合物属于三斜晶系,P-1空间群,a=1.51300(11)nm,b=1.74813(15)nm,c=2.58896(18)nm,α=72.842(4)°,β=89.240(5)°,γ=72.627(5)°,V=6.2233(8)nm3,Z=1,R1=0.0962,wR2=0.2572。化合物是高还原态的四帽α-Keggin结构钼钒多金属氧簇,通过簇阴离子4个钒帽上的端氧分别支撑4个镍过渡金属配合物,形成一个中性的多金属氧酸盐。多金属氧簇上的端氧与结晶水分子之间的强烈氢键使化合物形成了三维超分子结构。     

配体尺度对配合物结构及光催化降解活性的调节:从零维到一维的Cu(Ⅱ)配合物

合成了桥联吡啶类配体2,6-二(3′-吡啶乙炔基)-4-甲基苯胺(L1)和未见文献报道的尺度更短的桥联吡啶配体2,6-二(3′-吡啶基)-4-甲基苯胺(L2),在常温下分别将其与一水合醋酸铜(Cu(OAc)2·H2O,OAc-=CH3CO2-)进行配位反应获得零维的配位大环分子[Cu2(L1)(OAc)4]2(1)和一维的配位聚合物{[Cu2(L2)(OAc)4]·2CH2Cl2·CH3CN}n(2)。对获得的2个配合物进行了X射线单晶衍射、傅里叶红外光谱、元素分析等方面的结构表征。对比其结构可以发现,配合物1和2中均存在{Cu2(OAc)4}的二核铜簇,不同的是2个配合物中配体的配位取向不同:配位大环化合物1中的配体L1以U型构型与二核铜簇形成了“2+2”的平面配位大环结构,而化合物2中的配体L2则以Z型构型连接相邻的二核铜簇形成一维链状结构。2个化合物的结构差异是由于配体的尺度导致的,更短的尺度使得配位氮原子取向发生改变而产生不同的配位构型,这显示了结构调控中配体尺度的影响作用。通过测定配体与配合物在固态下的荧光发射性质,证实了铜的引入会猝灭配体自身的荧光发射;同时,采用亚甲基蓝(MB)为底物的光催化降解实验证明,大环配位分子的光催化降解活性明显优于一维配位聚合物,两者的催化活性均远远强于醋酸铜本身的催化活性。     

金属离子在液相氧化中的催化作用——Ⅹ.过渡金属氯化物与简单配体原位形成的配合物在环己烯氧化反应中的催化作用

本文研究了由过渡金属氯化物(MnCl₂、FeCl₂、CoCl₂、CuCl)与2,2′-二吡啶原位形成的配合物,在环己烯氧化反应中的催化性能以及配体性质对所形成的配合物催化性能的影响.结果表明,多种过渡金属氯化物可与2,2′-二吡啶原位形成有催化活性的配合物,其催化活性与金属离子性质、形成配合物能力以及配体性质有关.     

双掺杂介孔催化剂Fe-Ti-MCM-41的制备及催化性能

通过对负载型Ti-MCM-41催化材料进行铁离子掺杂, 制备了双掺杂介孔催化剂Fe-Ti-MCM-41. 采用XRD, FTIR, HRTEM, BET和ICP等方法对材料的组成和结构进行了表征, 并研究了金属铁离子掺杂量和后处理温度等对介孔钛硅催化材料氧化催化性能的影响. 当掺杂量较低时, 铁离子主要是通过化学键键合在分子筛上, 呈分子级分散, 得到的催化剂对环辛烯、 环己烯、 苯乙烯和2-甲基苯乙烯等底物都表现出较好的催化活性. 当掺杂量较高时, 金属易形成聚集态, 导致催化剂比表面积下降, 使催化活性降低.     

Y型分子筛固载Co(Salprn)配合物的制备及催化烯烃环氧化性能

采用自由配体法将双水杨醛缩丙二胺席夫碱钴配合物Co(Salprn)封装于Y型分子筛超笼中,并通过X射线衍射、漫反射UV-Vis光谱、FT-IR光谱和差热分析技术对所制备的催化剂进行了表征。该催化剂样品( [Co(Salprn)]-Y)在苯乙烯环氧化反应中较纯配合物Co(Salprn)表现出很高的催化活性。反应条件（包括溶剂、催化剂用量、异丁醛浓度和反应时间）对催化性能有较大影响。研究结果还表明,[Co(Salprn)]-Y对其他烯烃的环氧化也具有较高催化活性。其活性顺序为苯乙烯﹥环己烯﹥环辛烯﹥正辛烯。     

Keggin结构过氧铌钨磷杂多配合物的合成、表征及催化性能

钼钨的杂多化合物（HPC）在催化、电催化、分子材料、药物等诸多领域中已显示出独特的功能。含过氧金属离子取代的杂多阴离子在催化以过氧化氢为氧化剂的烯烃环氧化反应中具有很高的活性和选择性。近年来,含铌的杂多配合物由于良好的催化活性和抗病毒性,引起了人们的重视。本文合成了8种Keggin结构过氧铌钨磷杂多配合物,并用红外、紫外吸收光谱、极谱-循环伏安、及^183W NMR谱等测试手段对其结构和性质进行了确定和比较,考察了它们对烯烃环氧化反应的催化活性。     

多元多金属含氧簇合物在催化化学中的应用*

多金属含氧簇合物在催化化学中的重要性与日俱增,在原子经济反应和环境友好催化方面有着诱人的实用前景。这类物种的催化活性、理化性质、分子结构和固态体相结构以及制备方法均能在分子水平上给出详细信息,因而被视为混合金属氧化物催化剂的分子设计材料。本文拟对能够直观反映出这种信息的多元多金属含氧簇合物催化的研究作一评述。     

Molybdenum hexacarbonyl supported on amine modified multi‐wall carbon nanotubes: an efficient and highly reusable catalyst for epoxidation of alkenes with tert‐butylhydroperoxide

In the present work, highly efficient epoxidation of alkenes catalyzed by Mo(CO)₆ supported on multi‐wall carbon nanotubes modified by 2‐aminopyrazine, APyz‐MWCNTs, is reported. The prepared catalyst was characterized by elemental analysis, scanning electron microscopy, FT IR and diffuses reflectance UV–vis spectroscopic methods. This new heterogenized catalysts, [Mo(CO)₆@APyz‐MWCNT], was used as a highly efficient catalyst for epoxidation of alkenes with tert‐BuOOH. This robust catalyst was reused several times without loss of its catalytic activity. Copyright © 2010 John Wiley & Sons, Ltd.     

Olefin epoxidations in the ionic liquid [C4mim][PF6] catalysed by oxodiperoxomolybdenum species in situ generated from molybdenum trioxide and urea–hydrogen peroxide: The synthesis and molecular structure of [Mo(O)(O2)2(4-MepyO)2]·H2O

Commercially available molybdenum(VI) compounds, including molybdenum trioxide, were successfully employed as catalyst precursors in the epoxidation of olefins with urea–hydrogen peroxide adduct (UHP) in the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate, [C₄mim][PF₆]. After oxidation, the corresponding epoxides were isolated by extraction with diethyl ether. Additionally the ionic liquid–catalyst mixture was recycled and reused in further catalytic cycles. The catalytic species is assumed to be an oxodiperoxomolybdenum species which forms in situ. A representative complex of this type was thus isolated and characterised. Reaction of excess 4-methylpyridine-1-oxide (4-MepyO) with MoO₃ dissolved in aqueous hydrogen peroxide afforded [Mo(O)(O₂)₂(4-MepyO)₂]·H₂O (1) as yellow crystals. Compound 1, an active epoxidation catalyst, was subsequently characterised and its structure determined by X-ray crystallography.     

Distinct Chain/Layer Structures in Silver(I) Compounds: Synthesis,Structures, and Photoluminescent Properties

Two new hybrid inorganic‐organic compounds with different chain/layer structures, [Ag(bipy)]_n · n(Hdpa) · n(DMF) · n(H₂O) ( 1 ) and [Ag(dpa)_0.5(bix)_0.5]_n ( 2 ) [H₂dpa = diphenic acid, bipy = 4, 4′‐bipyridine, bix = 4, 4′‐bis(imidazol‐1‐ylmethyl)benzene, DMF = N,N′‐dimethylformamide] were successfully synthesized and characterized by elemental analysis, IR spectroscopy, and powder X‐ray diffraction. Single X‐ray analysis reveals that compound 1 is a one‐dimensional (1D) supramolecular double chain structure constructed by the combination of coordination bonds, hydrogen bonds, weak Ag ··· O and argentophilic interactions, compound 2 is a two‐dimensional (2D) undulated layer structure constructed by coordination bonds, weak Ag ··· O and argentophilic interactions. Moreover, the photoluminescent properties of the two compounds were also investigated in the solid state at room temperature.     

Post modification of zinc based coordination polymer to prepare Zn‐Mo‐ICP nanoparticles as efficient self‐supported catalyst for olefin epoxidation

Preparation, characterization, and catalytic properties of bimetallic coordination polymer constructed from 2‐aminoterephthalic acid as linker, zinc cations as node, and cis‐dioxo molybdenum units as catalytic active sites are reported via two pathways. Molybdenum centers were placed in N,O positions created by condensation reaction of 2‐aminoterephthalic acid with salicylaldehyde while zinc cations coordinated via carboxylic acid groups of linker to achieve infinite chains of metalo‐ligand. The obtained coordination polymer was fully characterized and its catalytic properties in the epoxidation of olefins with tert‐butyl hydroperoxide (TBHP) described. In comparison with previously reported heterogenized molybdenum catalysts, this new coordination polymer exhibited good conversion as well as high selectivity in the epoxidation of olefins. The catalyst is stable under ambient conditions and could be reused as active catalyst for at least five times.     

Syntheses and molecular structures of new cali

An unusual disproportionation reaction of the molybdenum(IV) and tungsten(IV) chlorides [MCl4L2] (M=Mo, L=Et2S, Et2O; M=W; L= Et2S) in the presence of p-tBu-calix[4]arene (Cax(OH)4) and triethylamine leads to d0 complexes [(CaxO4)[CaxO2(OH)2]M] (1) and d3 compounds (HNEt3)2[(CaxO4)2M2] (2). Complexes la (M = Mo), 1b (M = W), and the HCl adduct of 2a (M = Mo) have been structurally characterized. Compound 1a represents one of the few examples of a well-characterized molybdenum(VI) hexa-alkoxide complex of the type [Mo(OR)6]. Isolation and structural characterization of the side product [(CaxO4W)[kappa2(O)-kappa1(O)-CaxO3(OH)](CaxO4WCl)] (3) suggests the intermediacy of chloro-containing calix[4]arene complexes in these reaction mixtures. The reaction of 1a with HCI provides [CaxO4MoCl2] (4a), the first well-defined example of a mixed molybdenum(VI) alkoxide halide compound of the general formula [MoClx(OR)6-x].     

Synthesis and Crystal Structure of a New Mixed-ligand Cluster[Mo3O4(C2O4)2bipy-(H2O3)]·EtOH·2H2O(bipy=2,2''''-Bipyridine)

The novel mixed-ligand neutral compound [Mo3O4(C2O4)2·bipy(H2O)3]·EtOH·2H2O (bipy = 2,2'-bipyridine) has been prepared by the reaction of oxalic acid elution of Mo(Ⅳ) and bipy, and characterized by single-crystal X-ray diffraction analysis and IR. The crystal is of triclinic, space groups P1 with a = 9.5520(2), b = 10.3730(1), c = 13.5722(2) (A), α = 74.940(12), β = 80.772(14), γ = 69.898(11)°, V = 1215.73(11) (A)3, Z = 2, C16H24Mo3N2O18, Mr = 820.19, Dc = 2.241 g/cm3, μ = 1.616 mm-1, F(000) = 808, T= 293(2) K, the final R = 0.0424 and wR = 0.0939 for 4119 observed reflections with Ⅰ> 2σ(Ⅰ). The trinuclear unit is coordinated by mixed ligands of oxalate and bipy. The intermolecular hydrogen bonding interactions among adjacent [Mo3O4(C2O4)2·bipy(H2O)3] extend the compound into a therr-dimensional supramolecular framework. The uncoordinated water molecules and ethal molecules act as space-fillers and consolidate the whole architecture through hydrogen bonding interactions.     

Synthesis, structural elucidation, and application of a pyrazolylpyridine-molybdenum oxide composite as a heterogeneous catalyst for olefin epoxidation

The reaction of [MoO(2)Cl(2)(pypzEA)] (1) (pypzEA = ethyl[3-(pyridin-2-yl)-1H-pyrazol-1-yl]acetate) with water in a Teflon-lined stainless steel autoclave (100 °C) or in an open reflux system leads to the isolation of the molybdenum oxide/pyrazolylpyridine composite material [Mo(2)O(6)(HpypzA)] (2; HpypzA = [3-(pyridinium-2-yl)-1H-pyrazol-1-yl]acetate). The solid state structure of 2 was solved through single crystal and powder X-ray diffraction analyses in conjunction with information derived from FT-IR and (13)C CP MAS NMR spectroscopies and elemental analyses. In the asymmetric unit of 2, two crystallographically distinct Mo(6+) centers are bridged by a syn,syn-carboxylate group of HpypzA. The periodic repetition of these units along the a axis of the unit cell leads to the formation of a one-dimensional composite polymer, (∞)(1)[Mo(2)O(6)(HpypzA)]. The outstretched pyrazolylpyridine groups of adjacent polymers interdigitate to form a zipper-like motif, generating strong onset π-π contacts between adjacent rings of coordinated HpypzA molecules. The composite oxide 2 is a stable heterogeneous catalyst for liquid-phase olefin epoxidation.     

Catalysts for monooxygenations made from polyoxometalate: an iron(V)-oxo derivative of the Lindqvist anion

This work uses density functional calculations to design a new high-valent Fe(V)=O catalyst [Mo5O18Fe=O]3-, which is based on the Lindqvist polyoxometalate (Mo6O19(2-)). Because the parent species is stable to oxidative conditions, one may assume that the newly proposed iron-oxo species will be stable, too. The calculated M?ssbauer spectroscopic data may be helpful toward an eventual identification of the species. The calculations of C-H hydroxylation and C=C epoxidation of propene show that, if made, [Mo5O18Fe=O]3- should be a potent oxidant that will be subject to strong solvent effect. Moreover, the Lindqvist catalyst leads to an intriguing result; the reaction that starts along an epoxidation pathway with C=C activation ends with a C-H hydroxylation product ((4)6) due to rearrangement on the catalyst. The origins of this result are analyzed in terms of the structure of the catalyst and the electronic requirements for conversion of an epoxidation intermediate to a hydroxylation product. Thus, if made, the [Mo5O18Fe=O]3 will be a selective C-H hydroxylation reagent.     

SYNTHESIS AND STRUCTURE OF A NEW DINUCLEAR MOLYBDENUM(O) COMPLEX [Et_4N]_2 [Mo_2 (CO)_8 (SCH_2COOEt)_2]

<正> t Reaction of Et^NI, NaSCH2COOEt with Mo(CO)6 in MeCN affords a new dinuclear molybdenum(O) complex, [Eti,N]2 [Mo2(CO) 8(SCH2COOEt)2] (I) . The crystal and molecular structure has been determined from three-dimensional X-ray data. 1_ crystallizes in the triclinic, space group PI with a=10.362(1), b= 10.391(1), c=10.815(2) X, a=91.64(2), 6=100.07(2), Y=H4.46(1)? Z=l, R= 0.048 for 2975 reflections with I?o(I). Noribonding of Mo...Mo distance (3.939(11)A) in _! supports the previous speculation for the two-electron redox properity,of complex anion, [Mo2(CO)g(SR)2J2~.     

Synthesis,Crystal Structure of Cis—dioxo—catecholatotungsten（VI） Complex and Its NMR Studies on the Interaction with ATP

Cis-dioxo-catecholatotungsten(VI) complex anion[W^(VI)O2-(OC6H4O)2]^2- was obtained with discrete protonated ethylenediamine (NH2CH2CH2NH3)^ cations by the reaction of tetrabutyl ammonium decatungstate with catechol in the mixed solvent of CH3OH,CH3CN and ethylenediamine,and compared with its molybdenum anaogue [Mo^(V) O2(OC6H4O)2]^3- by crystal structure,UV,EPR,The results of the UV and EPR spectra show that tungsten is less redox active than molybdenum since the molybdenum is reduced from Mo(VI) to Mo(V) but tungsten stays in the original highest oxidized state Mo(VI) when they are crystallized from the solution above.It is worthy to note that [W^(VI)O2(OC6H4O)]^2- shows the same coordination structure as its molybdenum analogue in which the metal center exhibits distorted octahedral coordination geometry with two cis-dioxocatecholate ligands and might have the related coordination structure feature with the cofactor of flavoenzyme because [Mo^(V)O2(OC6H4O)2]^3- presented essentially the same EPR spectra as flavoenzyme.The NMR studies on the interaction of the title complex with ATP reveal that the reduction of W(VI) to W(V) occurs when the title complex is dissolved in D2O and the W(V) is oxidized again when ATP solution is mixed with original solution and the hydrolysis of the catecholato ligand take places at mean time being monitored by ^1H NMR and ^13C NMR spectra.