Investigation of Dienophile-TiCl(4) Complexation by Means of X-ray Absorption and (13)C-NMR Spectroscopies

Extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) techniques, in combination with (13)C-NMR spectroscopy, have been used to study the complexation of methyl acrylate (1), N-acryloylbenzylamine (2), O-acryloyl-(R)-pantolactone (3), methyl N-acryloyl-(S)-prolinate (4), and methyl N-acryloyl-(S)-phenylalaninate (5) with excess TiCl(4) in solution. The results obtained show that TiCl(4) has a great tendency to coordinate with two ester ligands, but this tendency is not so marked with amides, which is related to the greater basicity of the latter. Complexation increases the Ti-Cl bond distance, in comparison with TiCl(4), which is clearly shown by the EXAFS spectra. Chelate complexes are formed with bidentate ligands, but comparison between the EXAFS spectra, obtained with different TiCl(4)/dienophile ratios, shows that chelation is more difficult with methyl N-acryloyl-(S)-phenylalaninate (5).     

Formation of diphenylphosphanylbutadienyl complexes by insertion of two P-coordinated alkynylphosphanes into a PtbondC6F5 bond: detection of intermediate and reaction products

The reactions between cis-[M(C(6)F(5))(2)(PPh(2)CtriplebondCR)(2)] (M=Pt, Pd; R=Ph, tBu, Tol 2, 3) or cis-[Pt(C(6)F(5))(2)(PPh(2)CtriplebondCR)(PPh(2)CtriplebondCtBu)] (R=Ph 4, Tol 5) and cis-[Pt(C(6)F(5))(2)(thf)(2)] 1 have been investigated. Whereas [M](PPh(2)CtriplebondCtBu)(2) ([M]=cis-M(C(6)F(5))(2)) is inert towards 1, the analogous reactions starting from [M](PPh(2)CtriplebondCR)(2) or [Pt](PPh(2)CtriplebondCR)(PPh(2)CtriplebondCtBu) (R=Ph, Tol) afford unusual binuclear species [Pt(C(6)F(5))(S)mu-[C(R')dbondC(PPh(2))C(PPh(2))doublebondC(R)(C(6)F(5))]M(C(6)F(5))(2)] (R=R'=Ph, Tol, M=Pt 6 a,c, M=Pd 7 a,c; M=Pt, R'=tBu, R=Ph 8, Tol 9) containing a bis(diphenylphosphanyl)butadienyl bridging ligand formed by an unprecedented sequential insertion reaction of two P-coordinated PPh(2)CtriplebondCR ligands into a PtbondC(6)F(5) bond. Although in solution the presence of coordinated solvent S (S=(thf)(x)(H(2)O)(y)) in 6, 7 is suggested by NMR spectroscopy, X-ray diffraction analyses of different crystals of the mixed complex [Pt(C(6)F(5))mu-[C(tBu)doublebondC(PPh(2))C(PPh(2))doublebondC(Tol)(C(6)F(5))]Pt(C(6)F(5))(2)] 9 unequivocally establish that in the solid state the steric crowding of the new diphenylbutadienyl ligand formed stabilizes an unusual coordinatively unsaturated T-shaped 3-coordinated platinum(II) center. Structure determinations of the mononuclear precursors cis-[Pt(C(6)F(5))(2)(PPh(2)CtriplebondCR)(2)] (R=Ph, tBu, Tol) have been carried out to evaluate the factors affecting the insertion processes. The reactions of the platinum complexes 6 towards neutral ligands (L=CO, py, PPh(2)H, CNtBu) in a 1:1 molar ratio afford related diplatinum derivatives 10-13, whereas treatment with CNtBu (1:2 molar ratio) or 2,2'-bipy (1:1 molar ratio) results in the opening of the chelating ring to give cis,cis-[Pt(C(6)F(5))(L)(2)mu-[1-kappaC(1):2-kappaPP'-C(R)doublebondC(PPh(2))C(PPh(2))doublebondC(R)(C(6)F(5))]Pt(C(6)F(5))(2)] (14, 15). The unsaturated or solvento complexes are unstable in solution evolving firstly, through an unexpected formal 4-1 R (Ph, Tol) migration, to the intermediate diphosphanylbutadienyl isomer derivatives [Pt(C(6)F(5))(S)mu-[C(C(6)F(5))doublebondC(PPh(2))C(PPh(2))doublebondC(R)(2)]M(C(6)F(5))(2)] (16, 18) (X-ray, R=Ph, M=Pt) and, finally, to 1-pentafluorophenyl-2,3-bis(diphenylphosphanyl)naphthalene mononuclear complexes (17, 19) by annulation of a phenyl or tolyl group.     

自调心伪双CCD光切360°三维轮廓测量系统

针对双 CCD三角测量系统的调心问题,提出一种利用单 CCD辅以可控机械回转臂实现光切 360°三维轮廓测量的新方案,给出了测量原理及系统结构,并详细介绍了映射函数法标定系统的原理及其具体实现.实物测量结果表明,该方法除具有双 CCD光切测量系统的全部优点外,测量系统可实现自动定心,后序数据融合简单,测量精度高,系统造价较低.     

聚甲醛/蒙脱土纳米复合材料非等温结晶动力学研究

聚甲醛/蒙脱土纳米复合材料非等温结晶动力学研究     

A Rule to Design High Spin Molecules with Hetero spin Centers

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Theoretical Studies on the Reaction Mechanism of AsCl3 with H2 in the Vapor Phase Epitaxy of GaAs

The reaction mechanism of AsCl3 with H2 has been studied by using the method of BHandHLYP in Density Functional Theory (DFT) at the 6-311G** basis set. The transition state of each reaction is verified via the analysis of vibration mode and Intrinsic Reaction Coordinate (IRC). Meanwhile,single-point energy has been calculated at the QCISD(T)/6-311G** level,and the zero-point energy correction has been made to the total energy and reaction energy barrier. It shows that AsCl3 reacts with H2 to first result in AsHCl2 which may incline to self-decompose and finally afford the product As2,or continue to react with H2 to provide the product AsH3. The computing result demonstrates that the former is the main reaction channel.     

DFT Studies on Hydrogen Overfall Mechanism for Catalyzed Hydroisomerization of Pentane

The mechanism and related reaction paths in the hydroisomerization of n-pentane were studied by DFT calculations at the B3LYP/6-311++G** level. Two possible transition states were theoretically predicted and verified by the vibration frequency analysis as well as the calculations of intrinsic reaction coordinates (IRC). Furthermore, the related reaction barriers were evaluated by single point energy at the MP2/6-311++G** level with zero point vibration correction of DFT method. Thus, it is concluded that the isomerization might go through two pathways.     

Synthesis, Structure and Antibacterial Activities of 4-BBTS Schiff Base and Its Complexes

4-Bromobenzaldehyde thiosemicarbazone Schiff base (4-BBTS) and its Cu(II), Zn(II), Co(II) and Ni(II) complexes were synthesized and characterized by elemental analysis, UV, IR, MS, 1H NMR, and molar conductivity. Using disc diffusion method, the antibacterial activity tests were conducted. The results revealed that the ligand as well as all the complexes exhibits good antibacterial activities against E. Coli. and S. Aureus. Moreover, Cu(II) complex shows the best antibacterial activity, which provides beneficial reference for studying the relationship between the structures and performances.     

新型对称烷基咪唑离子液体介质中酶催化合成l-乙酸薄荷酯

设计合成三种新型对称烷基咪唑六氟磷酸盐离子液体——1,3-二正丁基咪唑六氟磷酸盐([DnBIM][PF6]), 1,3-二异丁基咪唑六氟磷酸盐([DiBIM][PF6])和1,3-二仲丁基咪唑六氟磷酸盐([DsBIM][PF6]). 以脂肪酶pseudomonas cepacia催化l-薄荷醇和乙酸酐的酯化过程为模型反应, 分别考察不同介质中酶的活性、反应性和稳定性, 结果表明作为反应介质三种新型离子液体均优于经典离子液体1-正丁基-3-甲基咪唑六氟磷酸盐和有机溶剂正己烷. 在三种新的离子液体中, [DiBIM][PF6]具有最好的亲生物性而被选择作为模型反应介质. 此外, 影响l-薄荷醇转化率的各种因素(包括反应温度、底物投料比、离子液体用量和含水量)及酶的重复利用性也被详细研究. 在最佳反应条件下, l-薄荷醇转化率达到97.4%, 酶促反应速度、平衡转化率和半衰期分别是正己烷中的12.7, 4.6和15.1倍. 脂肪酶重复使用10次后催化活性没有明显减少. 由于三种新型离子液体互为同分异构体, 以上事实还表明除憎水性和亲核性以外离子液体的空间构型也是影响酶行为的一个重要因素.     

应用腙作为配体的铜催化二芳醚合成反应

一种简单易得的腙,2-吡啶醛 1-苯基腙 （1）,能够作为有效配体,极大地促进碘化铜催化的芳基溴与酚的C–O偶联反应。该偶联反应条件温和（二氧六环为溶剂、磷酸钾为碱、90–100 0C 的反应温度）,适用于各种芳基溴（电中性、贫电子和富电子）和酚（电中性和富电子）的底物,能够相容一些碱敏感官能团如酯基、醛基和羰基等。