三联苯基配体稳定的锇-锗配合物合成及表征

研究了锇-锗单键双金属配合物[OsGe(ArTrip)(PPh₃)(H)Cl₂] (1)的反应性,其中ArTrip=C₆H₃-2-(η⁶-Trip)-6-Trip,Trip=2,4, 6-ⁱPr₃-C₆H₃。通过与不同试剂反应,成功合成并表征了3个新型锇-锗双金属配合物。通过配合物1与EtMgBr反应合成了锗原子上氯原子被溴原子取代的产物[OsGe(ArTrip)(PPh₃)(H)Br₂] (2);1与LiHBEt₃反应合成了锗原子上氯原子被乙基取代的产物[OsGe(ArTrip)(PPh₃)(H)Et₂] (3);1与HBF₄作用合成了加成产物[OsGe(ArTrip)(PPh₃)(H)₂Cl₂]BF₄ (4)。配合物4不稳定,在H₂O (n_H2O/n₄=1)作用下能转化为配合物1。     

钌配合物催化氢化CO2生成甲酸反应中的醇促进效应

在水合钌配合物[TpRu(PPh₃)₂(H₂O)]BF₄ [Tp＝hydrotris(pyrazolyl) borate]催化氢化二氧化碳生成甲酸的反应中观察到醇对反应的促进作用. 利用原位高压核磁共振跟踪催化反应过程的结果表明, 在甲醇溶液中, [TpRu(PPh₃)₂(H₂O)]BF₄在三乙胺和H₂作用下转化为TpRu(PPh₃)₂H. 二氧化碳插入Ru—H生成甲酸根配合物TpRu(PPh₃)₂(η¹-OCHO)•HOCH₃, 其中的甲酸根配体与醇分子间形成分子间氢键. 该甲酸根配合物随即转化为另一个甲酸根配合物TpRu(PPh₃)(CH₃OH)(η¹-OCHO)并与之达成平衡, 后者由于存在分子内氢键而稳定. 考虑到这两个甲酸根配合物在催化反应中的稳定性, 它们应该不在主要的催化循环内. 提出了配合物[TpRu(PPh₃)₂(H₂O)]BF₄在几种醇溶液中催化氢化二氧化碳生成甲酸的催化循环机理, 催化循环的关键中间体可能是TpRu(PPh₃)(ROH)H. 该中间体能同时转移负氢及醇配体中的氢质子到接近的二氧化碳分子上生成甲酸, 并吸收H₂生成过渡态TpRu(PPh₃)(OR)(H₂). 该过渡态经过σ-复分解反应重新生成TpRu(PPh₃)(ROH)H完成催化循环.     

两个含有杂环硫酮的银(Ⅰ)配合物的合成、晶体结构和光谱特性

合成了2个含有杂环硫酮的银(Ⅰ)配合物,[AgBr(PPh₃)₂(BTZT)]₂(1),[Ag₂Cl₂(PPh₃)₂(BTZT)₂]CH₃OH(2)(PPh₃=三苯基膦;BTZT=苯并噻唑-2-硫酮),并通过红外光谱、X射线单晶衍射、荧光光谱和核磁氢谱进行表征。2个配合物是在含有2-巯基苯并噻唑(MBT)的甲醇与二氯甲烷混合溶液中,AgX(X=Cl,Br)与三苯基膦反应得到的。MBT配体由于存在化学活性基团(-N(H)-C(=S)-),所以可以转化为BTZT配体。结构分析显示有2个相同的分子结构存在于配合物1中,但是它们具有不同的键长和键角。配合物2是一个含有菱形的[Ag₂Cl₂]单元在中心的反转对称二聚体,2个相邻[AgCl(PPh₃)(BTZT)]单元由2个氯原子桥连。     

以吡嗪四甲酸为配体的配合物的合成及表征

合成了两种金属配合物{[Cu₂(pztc)(4,4'-bpy)(H₂O)₄]·6H₂O}_n (1),{(H₂bpe)[Cd(pztc)(H₂O)₂]·2.5H₂O}_n (2)(H₄pztc=吡嗪-2,3,5,6-四甲酸,bpy=4,4'-联吡啶,bpe=1,2-二(4-吡啶基)乙烯),测定了其晶体结构,并对其进行了红外光谱、荧光光谱和热重分析等表征。两种配合物均为二维层状结构,但其中吡嗪四酸的配位方式不同。配合物2具有蓝色的荧光,最大荧光发射峰在475 nm。测试了配合物1的电子顺磁共振谱,结果显示Cu²⁺的特征谱带。     

两个含有杂环硫酮的银(Ⅰ)配合物的合成、晶体结构和光谱特性

合成了2个含有杂环硫酮的银(Ⅰ)配合物,[AgBr(PPh₃)₂(BTZT)]₂ (1),[Ag₂Cl₂(PPh₃)₂(BTZT)₂]CH₃OH (2)(PPh₃=三苯基膦;BTZT=苯并噻唑-2-硫酮),并通过红外光谱、X射线单晶衍射、荧光光谱和核磁氢谱进行表征.2个配合物是在含有2-巯基苯并噻唑(MBT)的甲醇与二氯甲烷混合溶液中,AgX(X=Cl,Br)与三苯基膦反应得到的.MBT配体由于存在化学活性基团(-N(H)-C(=S)-),所以可以转化为BTZT配体.结构分析显示有2个相同的分子结构存在于配合物1中,但是它们具有不同的键长和键角.配合物2是一个含有菱形的[Ag₂Cl₂]单元在中心的反转对称二聚体,2个相邻[AgCl(PPh₃)(BTZT)]单元由2个氯原子桥连.     

三个二羧酸配体配位聚合物的合成、结构表征和荧光性质

以羧酸配体 2,2''-(1,4-亚苯基双(亚苯基))双(硫二基)二苯甲酸(H₂L¹)和 2,2''-(2,3,5,6-四甲基-1,4-亚苯基)双(亚甲基）双(硫二基)二苯甲酸(H₂L²)分别与金属盐反应,通过溶剂热方法合成了 3个配位聚合物：{[Ni(L¹)(H₂O)₄]·2H₂O}_n (1)、[Zn(L¹)(DMA)₂]_n(2)和[Co(L²)(DMF)₂]_n (3),其中DMA=N,N-二甲基乙酰胺,DMF=N,N-二甲基甲酰胺。对配合物1~3进行了单晶X射线衍射、元素分析、红外光谱、热重分析、粉末X射线衍射和固体紫外可见光谱测试和表征。单晶X射线衍射表明：3个配合物均为一维锯齿形链状结构,并通过氢键作用形成三维骨架,且配体均表现为反式构象。此外,对配合物2固态荧光性质进行了研究。     

巢式十一顶铂硼烷簇合物的合成与晶体结构

[PtCl₂(PPh₃)₂]与B₁₀H₁₀^2－在异丙醇中回流反应, 得到3个巢式十一顶铂十硼烷簇合物: [(PPh₃)₂PtB₁₀H₁₁-9-O-i-Pr] (1), [(PPh₃)₂PtB₁₀H₁₀-8,10-(O-i-Pr)₂] (2)和[(PPh₃)₂PtB₁₀H₁₁-8-O-i-Pr] (3). 簇合物1～3都具有PtB₁₀多面体骨架结构, 其中Pt原子位于敞开的PtB₄面上, 且与4个B原子成键, 每个Pt原子还与2个PPh₃基团中的P原子成键. 将溶剂热合成的方法引入到硼簇合物的合成中并进行同一反应, 得到2个B₁₀H₁₀^2－降解的巢式十一顶双铂九硼烷簇合物: [(PPh₃)₂(μ-PPh₂)Pt₂B₉H₆-3,9,11-(O-i-Pr)₃] (4)和[(PPh₃)₂(μ-PPh₂)Pt₂B₉H₆-3,9-(O-i-Pr)₂-11-Cl] (5). 簇合物4和5都具有Pt₂B₉多面体骨架结构, 2个Pt原子位于敞开的Pt₂B₃面上的相邻位置, 且由一个PPh₂基团桥连, 每个Pt原子还与3个B原子和一个PPh₃基团中的P原子成键. 通过红外光谱、元素分析、X射线单晶衍射对5个簇合物进行了结构表征.     

基于2,4,6-吡啶三羧酸配体桥连的铁(Ⅱ)/镍(Ⅱ)配位聚合物的水热合成及结构表征

在水热反应条件下FeCl₂·6H₂O、2,4,6-吡啶三羧酸(H₃pyta)和NaOH反应合成了1种一维链状铁配位聚合物[Fe₃(pyta)₂(H₂O)₈] (1);同样条件下Ni(OAc)₂·4H₂O、2,4,6-吡啶三羧酸(H₃pyta)、NaOH和4-氨基-3,5-二(4-吡啶基)-1,2,4-三氮唑(abpt)反应合成了1种二维网状镍配合物[Ni₃(pyta)₂(abpt)₂(H₂O)₃]·2H₂O (2)。通过元素分析和红外光谱对这2个配位聚合物进行了表征。单晶结构表明：配合物1的晶体属于单斜晶系,Cc空间群;配合物2的晶体属于单斜晶系,P2₁/c空间群。在配合物1中,pyta^3-配体采取μ₂-和μ₄-pyta^3- 2种桥连模式将Fe原子连成了沿c轴方向延伸的Fe-pyta链。而在配合物2中,pyta^3-配体仅采取μ₂-桥连模式将Ni原子连成线型三核[Ni₃(pyta)₂]单元,这些三核单元进一步通过abpt辅助配体桥连成二维 (4,4)层状结构。     

由芳香羧酸和1,3,5-三咪唑基苯为配体构筑的锌、镉配合物的合成、结构和荧光性质

通过水热法得到了2个配位聚合物{[Zn(timb)(BTEC)_0.5]·H₂O}_n(1)和{[Cd(timb)(DPA)]·H₂O}_n(2)(timb=1,3,5-三咪唑基苯,H₄BTEC=均苯四甲酸,H₂DPA=2,2-联苯二甲酸),对它们进行了元素分析、红外光谱分析,并利用X射线衍射测定了它们的单晶结构。 配合物1属于三斜晶系,P1空间群。配合物2属于单斜晶系,C2/c空间群。配合物1拥有一个不寻常的三维框架结构,其拓扑为(4.6³·8⁶)₂(4²·8⁴)(6³)₂;而配合物2具有一维单层纳米管结构。结果说明了金属离子和有机羧酸配体在配合物组装过程中起着非常重要的作用。此外,在室温下对2个配合物进行了荧光性质分析。     

基于吡啶基苯甲酸盐的两个银(Ⅰ)配合物的合成、晶体结构及荧光性质

合成了2个含有吡啶基苯甲酸盐的银(Ⅰ)配合物,即[Ag₂(PPh₃)₂(4,4-pybz)₂(H₂O)₂]_n(1)和[Ag₂(PPh₃)₂(4,3-pybz)₂]·2CH₃OH(2)(PPh₃=三苯基膦,4, 4-pybz=4-吡啶-4-基-苯甲酸根, 4,3-pybz=4-吡啶-3-基-苯甲酸根),并通过红外光谱、元素分析和荧光光谱进行分析和表征,它们的结构由X射线单晶衍射测定。在不同的溶剂下,2个配合物由AgBF₄、PPh₃和不同的吡啶苯甲酸在氨水作用下,以1:1:1的比例反应而成。在配合物1中,所有的银原子由吡啶基苯甲酸桥连形成一维链状结构。在配合物2中,2个银原子通过2个4-吡啶-3-基-苯甲酸根配体形成双核结构。在荧光光谱中,在发射状态下所有的峰均来源于配体的π-π*跃迁。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.