脲盐的电子结构及其与光谱和能谱的关系

对脲盐的振动和电子光谱及Ｘ光电子能谱进行研究，并用电荷自洽场ＤＶ－Ｘα方法计算其电子结构，确定脲盐正离子ＣＯ（ＮＨ２）２Ｈ＾＋的结构特征，分析其结构变化与光谱和能谱现象的内在联系，并由此提出了形成配合物的反应机理。     

用固体核磁共振和电子能谱研究我国高硫煤的结构

用固体ＮＭＲ和ＸＰＳ技术研究了我国三种（广西合山煤、湖南辰溪煤、浙江长广煤）高硫煤的结构特征。由固体ＮＭＲ测试结果计算出煤的十二种结构参数和芳香簇团的大小，获得了三个样品的结构特征及变化规律，由ＸＰＳ测试结果得到了煤中各种不同形态硫、氮的结合能数值。根据前入所做的模型化合物的结果，得知三咱煤中硫元素主要以噻吩硫形态存在，氮元素主要以吡啶和中的形态存在。     

尖晶石型铁酸盐的制备及表征研究

本文采用空气氧化的湿法制备了尖晶石型铁酸盐，得到最佳生成条件为：在空气流速为２００ｍｌ／ｍｉｎ和配料比Ｒ＝２ＯＨ－／（Ｍ２＋＋Ｆｅ２＋）≥１．０，Ｍ２＋／Ｆｅ２＋＝０．５（摩尔比）下氧化温度和时间分别为３４３－３５８Ｋ和１０－２５ｈ。使用ＸＲＤ、ＴＰＲ和ＴＰＤ等方法对所制备的铁酸盐进行了表征，研究了其结构特征及氧化－还原活性，并讨论了该活性与化学组成及结构的关系。     

辐照聚乙烯的熔融和重结晶

用差示扫描量热法（ＤＳＣ），小角Ｘ－射线散射（ＳＡＸＳ），广角Ｘ－射线衍（ＷＡＸＤ）等考察了辐照聚乙烯的熔融和重结晶，辐照破坏了聚乙烯结晶结构，使其熔融温度、结晶度均随辐照剂量的增加而降低，将辐聚乙烯熔融再结晶，其重结晶度、熔融温度随辐照剂量而下降的幅度较大，其原因被归结为片晶劈裂。     

B_nX_n~（0，2－）（X＝H，Cl；n＝4，6，8，9，10，12）稳定性的从头计算研究

用双ζ型收缩高斯基对全卤代硼烷Ｂ_ｎＸ_ｎ~（０，２－）及相应硼烷Ｂ_ｎＸ_ｎ~（０，２－）（ｎ＝４，６，８，９，１０，１２）进行了从头计算。讨论中性卤代硼烷稳定存在的原因及Ｂ_ｎＣｌ_ｎ与Ｂ_ｎＸ_ｎ~（０，２－）稳定性随ｎ变化的不同趋势，并通过对Ｂ_４Ｘ_ｎ~（０，２－）结构规则的计算与分析，提出骨架成键轨道未填满电子是Ｂ_４Ｘ_ｎ~（０，２－）不稳定及迄今尚未发现中性Ｂ_ｎＨ_ｎ存在的重要原因。     

含两种不同介晶基团的半刚性共聚酯液晶态的结构研究

用Ｘ－光衍射，偏光显微镜及ＤＳＣ对含两种不同长度介晶基团４，４’－联苯二酚（Ⅰ）和对苯二甲酸二（对羟苯基）酯（Ⅱ）的系列共聚酯的液晶态进行了表征，据其液晶态中两种介晶单元的堆砌方式提出了可能的模型，这种模型很好地解释了液晶态的Ｘ－光衍射分布．     

三缺位杂多化合物K_8［P_2W_（18）Mo_2Co_2（H_2O）_2O_（68）］·MoO_6·15H_2O的合成、结构及催化H_2O_2分解研究

合成了杂多化合物Ｋ８［Ｐ２Ｗ（１８）Ｍｏ２Ｃｏ２（Ｈ_２Ｏ）２Ｏ（６８）］·ＭｏＯ６·１５Ｈ２Ｏ，依据ＸＲＤ、ＩＲ、ＵＶ－Ｖｉｓ及ＸＰＳ确定了其晶体结构和配位原子价态，考察了该化合物催化Ｈ２Ｏ２分解的动力学行为。     

载体对氧化铜高温脱硫过程影响的研究

通过ＸＲＤ（Ｘ－射线衍射），ＸＰＳ（Ｘ－射线光电子能谱），ＴＰＳ（程序升温硫化）及固定床脱硫性能测试等手段对负载型氧化铜脱硫剂进行了较系统的研究，结果表明载体的存在减小了内扩散阻力，提高了单位氧化铜脱硫剂的硫容，氧化铜在不同载体上的分散状态也不尽相同，Ｃ２ｐ３／２，Ｏ１ｓ自由能存在明显差异，ＴＰＳ研究表明不同载体上的单层分散的及未分散的氧化铜的硫化温度也存在区别。     

交流示波极谱滴定法测定氧氟沙星

１引言氧氟沙星（Ｏｆｌｏｘａｃｉｎ，ＯＦＬＸ）为新一代喹喏酮类抗菌药，其含量测定，文献报道可用分光光度法、ＨＰＬＣ、毛细管电泳法、离子选择电极法等。本文详细研究了交流示波极谱滴定法测定ＯＲＬＸ的实验条件，并用以测定其注射液和片剂的含量。２实验部分２．１仪器与试剂交流示波极谱仪，按文献（高鸿，示波极谱滴定，南京：江苏科技出版社，１９８５：１７）组装，ＵＶ－７５４分光光度计（上海第三分析仪器厂），ＯＦＬＸ注射液、片剂、化学对照品（北京制药厂）。容量仪器均经过校正，所用试剂四苯硼钠、硫酸亚铊及ＨＡｃ－…     

掺杂Tb3+的混合碱土金属钨酸盐的合成和性质

合成了掺杂Ｔｂ（３＋）的混合碱土金属钨酸盐，测定了其发射光谱和激发光谱，用粉末Ｘ射线衍射和电子衍射法表征了其晶体结构，并对钨酸钙钡单晶体进行了Ｘ射线能谱成份分析．探讨了碱土金属钨酸盐的溶混性成因以及在这些晶体中Ｔｂ（３＋）发光和能量传递机理．     

Theoretical study of reaction pathways for the rhodium phosphine-catalysed borylation of C-H bonds with pinacolborane

The reaction mechanism of the rhodium-phosphine catalysed borylation of methyl-substituted arenes using pinacolborane (HBpin) has been investigated theoretically using DFT calculations at the B3PW91 level. Factors affecting selectivity for benzylic vs. aromatic C-H bond activation have been examined. It was found that [Rh(PR3)2(H)] is the active species which oxidatively adds the C-H bond leading to an eta3-benzyl complex which is the key to determining the unusual benzylic regioselectivity observed experimentally for this catalyst system. Subsequent reaction with HBpin leads to a [Rh(PR3)2(eta3-benzyl)(H)(Bpin)] complex from which B-C reductive elimination provides product and regenerates the catalyst. The electrophilic nature of the boryl ligand assists in the reductive elimination process. In contrast to Ir(L)2(boryl)3-based catalysts, for which Ir(III)-Ir(V) cycles have been proposed, the Rh(I)-Rh(III) cycle is operating with the system addressed herein.     

Mechanism of the oxidative carbonylation of terminal alkynes at the ≡C-H bond in solutions of palladium complexes

The formation mechanism of the active catalyst in the oxidative carbonylation of terminal alkynes at the ≡C-H bond has been investigated for the catalytic system Pd(OAc)₂-PPh₃-p-benzoquinone (Q)-MeOH. It has been demonstrated by NMR spectroscopy, X-ray crystallography, and kinetic measurements that the catalytically active palladium is in the oxidation state 0 and is bound into complexes stabilized by p-benzoquinone (PdL₂Q, where L = PPh₃). A mechanism is suggested for the catalytic process, which includes the formation of the complex PdL₂Q, the oxidative addition of the alkyne to this complex at the ≡C-H bond, the insertion of CO into the Pd-C bond, and steps in which hydride hydrogen is intramolecularly transferred to the p-quinone.     

Bis(di-t-butylphosphino)methane complexes of rhodium: homogeneous alkyne hydrosilylation by catalyst-dependent alkyne insertion into Rh---Si or Rh---H bonds. Molecular structures of the dimer [(dtbpm)RhCl]2 and of the silyl complex (dtbpm) Rh[Si(OEt)3](PMe3)

The homogeneous, Rh-catalysed hydrosilylation of but-2-yne with triethoxysilane has been studied. All rhodium complexes employed as catalyst precursors contain ^tBu₂PCH₂P^tBu₂ (“dtbpm”) as a chelating ligand. The crystal and molecular structure of the dimer [(dtbpm)RhCl]₂ (10) has been determined by X-ray diffraction. Complex 10 is shown to be a sluggish catalyst in hydrosilylation reactions of hex-1-ene, whereas but-2-yne is hydrosilylated more rapidly. A much more efficient and highly selective catalyst is 10 with added PPh₃, equivalent to the use of monomeric (dtbpm)RhCl(PPh₃). (E)-2-Triethoxysilylbut-2-ene is formed exclusively and with high turnover numbers in this case. For both 10 and its PPh₃ derivative, the 14-electron fragment [(dtbpm)RhCl], formed by dissociation processes, is the most likely active intermediate in a Harrod-Chalk-type catalytic cycle. The PPh₃ dissociation equilibrium has been studied in detail for (dtbpm)RhCl(PPh₃) and its thermodynamic parameters have been determined. With rhodium alkyl complexes as catalyst precursors, a different type of alkyne hydrosilylation catalysis, involving direct alkyne insertion into the Rh---Si bond of an intermediate rhodium silyl complex, (dtbpm)Rh[Si(OEt)₃](PMe₃) (14), has been found. Complex 14 was synthesized independently from (dtbpm)RhMe(PMe₃) and characterized by X-ray diffraction. It is an equally active catalyst itself, yielding (E)-2-triethoxysilylbut-2-ene as the major product (90%) from but-2-yne and HSi(OEt)₃ (turnover number 1000 per 30 min). The insertion step of the alkyne into the Rh---Si bond of 14 and the formation of two stereoisomeric rhodium vinyl complexes were established independently for MeO₂CCCCO₂Me as a more reactive alkyne substrate. A catalytic cycle is proposed for this unprecedented hydrosilylation reaction. The synthesis of the ν³-benzyl complex (dtbpm)Rh(η³-CH₂C₆H₅) (23) is described. This compound allows an alternative, more efficient access to the new silyl complex (dtbpm)Rh[Si(OEt)₃](PMe₃).     

Mechanism of Polymerization of α-Olefins on Oxide Catalysts

The polymerization of ethylene on a chromic oxide catalyst with and without a solvent has been studied. It was found that the active catalyst surface is formed exclusively as a result of its interaction with ethylene. This interaction is accompanied by the formation of products which poison the surface of the catalyst when they are sorbed on it in the absence of a solvent. A catalyst which contains no Cr⁺⁶ atoms as a result of reduction by alcohol is inactive. On the other hand, a catalyst which contains only Cr⁺⁶ atoms becomes active only after it has been partially reduced. The most probable product of this reduction is trivalent chromium atoms. The results obtained have given grounds for the assumption that the active complex contains Cr⁺⁶ and Cr⁺³ atoms. A possible mechanism of the reaction is discussed. Owing to the oxidative action of CrO₃ on the ethylene molecules, part of the Cr⁺⁶ is reduced to Cr⁺³, and the trivalent chromium becomes alkylated. The monomer molecule is added at the Cr⁺³—C bond thus formed. A strong Lewis acid, CrO₃, lowers the electron density on the Cr⁺³ atom. This increases the strength of the Cr⁺³—C bond and the ability of the Cr⁺³ atom to coordinate with the monomer molecule. The monomer molecule enters the chain at the moment when the strength of the Cr^?3—C bond is weakened due to coordination of this molecule with the Cr⁺³ atom.     

Recent advances in the synthetic and mechanistic aspects of the ruthenium-catalyzed carbon-heteroatom bond forming reactions of alkenes and alkynes

The group’s recent advances in catalytic carbon-to-heteroatom bond forming reactions of alkenes and alkynes are described. For the C-O bond formation reaction, a well-defined bifunctional ruthenium-amido catalyst has been successfully employed for the conjugate addition of alcohols to acrylic compounds. The ruthenium-hydride complex (PCy₃)₂(CO)RuHCl was found to be a highly effective catalyst for the regioselective alkyne-to-carboxylic acid coupling reaction in yielding synthetically useful enol ester products. Cationic ruthenium-hydride catalyst generated in-situ from (PCy₃)₂(CO)RuHCl/HBF₄·OEt₂ was successfully utilized for both the hydroamination and related C-N bond forming reactions of alkenes. For the C-Si bond formation reaction, regio- and stereoselective dehydrosilylation of alkenes and hydrosilylation of alkynes have been developed by using a well-defined ruthenium-hydride catalyst. Scope and mechanistic aspects of these carbon-to-heteroatom bond forming reactions are discussed.     

Interaction of water, alkyl hydroperoxide, and allylic alcohol with a single-site homogeneous Ti-Si epoxidation catalyst: A spectroscopic and computational study

Tetrakis(trimethylsiloxy)titanium (TTMST, Ti(OSiMe3)4) possesses an isolated Ti center and is a highly active homogeneous catalyst in epoxidation of various olefins. The structure of TTMST resembles that of the active sites in some heterogeneous Ti-Si epoxidation catalysts, especially silylated titania-silica mixed oxides. Water cleaves the Ti-O-Si bond and deactivates the catalyst. An alkyl hydroperoxide, TBHP (tert-butyl hydroperoxide), does not cleave the Ti-O-Si bond, but interacts via weak hydrogen-bonding as supported by NMR, DOSY, IR, and computational studies. ATR-IR spectroscopy combined with computational investigations shows that more than one, that is, up to four, TBHP can undergo hydrogen-bonding with TTMST, leading to the activation of the O-O bond of TBHP. The greater the number of TBHP molecules that form hydrogen bonds to TTMST, the more electrophilic the O-O bond becomes, and the more active the complex is for epoxidation. An allylic alcohol, 2-cyclohexen-1-ol, does not interact strongly with TTMST, but the interaction is prominent when it interacts with the TTMST-TBHP complex. On the basis of the experimental and theoretical findings, a hydrogen-bond-assisted epoxidation mechanism of TTMST is suggested.     

Intermediacy of an N-heterocyclic carbene complex in the catalytic C-H activation of a substituted benzimidazole

An N-heterocyclic carbene complex was found to be the active catalyst in the Rh(I)-catalyzed intramolecular coupling of an alkenyl group to a C-H bond of a substituted benzimidazole. Kinetic studies demonstrated that the catalytic cyclization is zero-order in substrate and first-order in catalyst. Furthermore, DFT calculations with a model system suggest that the rate-limiting step involves insertion of the alkenyl double bond into the rhodium-carbene bond.     

Polymerization of vinyl chloride by use of modified Ziegler–Natta catalysts. I. Overall kinetic features

Vinyl chloride has been polymerized by a modified Ziegler-Natta type catalyst VOCl₂ · 2THF–Al(i-Bu)₃–THF, and the kinetics of the polymerization reaction have been investigated in some detail. The present kinetic analysis has demonstrated that the generation of active centers is directly proportional to the catalyst concentration, and that their depletion is by a second-order decay process. Triisobutylaluminum has been found to contribute to the effective removal of active centers through complex formation.     

An imidazolium ionic liquid having covalently attached an oxime carbapalladacycle complex as ionophilic heterogeneous catalysts for the Heck and Suzuki-Miyaura cross-coupling

An oxime carbapalladacycle, analogous to that used as catalyst in homogeneous phase, has been derivatized to increase its ionophilicity by introducing an imidazolium group covalently attached through a chain at the complex. The resulting complex is soluble in 1-butyl-3-methylimidazolium ionic liquid (bmimPF₆) and not extractable by ether. The catalytic activity of this palladium complex in bmimPF₆ is, however, unsatisfactory and only increases marginally in bmimPF₆/supercritical CO₂. This limitation has been overcome by supporting this imidazolium palladium complex on high surface area Al/MCM-41 aluminosilicate, whereby a solid active catalyst for the Suzuki cross-coupling has been obtained. Reusability and stability over reuse for this Al/MCM-41-supported catalyst have been studied.     

Ruthenium-catalyzed enantioselective carbon-carbon bond forming reaction via allenylidene-ene process: synthetic approach to chiral heterocycles such as chromane, thiochromane, and 1,2,3,4-tetrahydroquinoline derivatives

Our previously disclosed ruthenium-catalyzed carbon-carbon bond forming reactions between propargylic alcohols and alkenes via an allenylidene-ene type pathway have been successfully applied to an enantioselective intramolecular cyclization for a variety of chiral heterocycles such as chromane, thiochromane, and 1,2,3,4-tetrahydroquinoline derivatives (up to 99% ee) by use of a suitable optically active diruthenium complex as a catalyst. The methodology described in this paper becomes a novel synthetic approach to chiral heterocycles, the structures of which are widely found in many natural and biologically active compounds.