Preparation and catalytic applications of partially fluorinated binaphthol ligands

New partially fluorinated binaphthols were obtained using a copper-catalyzed oxidative coupling. The corresponding enantiomerically pure compounds were prepared by fractional crystallization of the corresponding bis(menthyl)carbamates. Nucleophilic aromatic substitution using oxygen- and carbon-based nucleophiles resulted in functionalized derivatives without concomitant racemization. The titanium(IV) complexes of these ligands are catalytically active in the asymmetric oxidation of sulfides.     

The relative reactivities of various unsaturated compounds towards diisopropyloxy(η-cyclopentene)titanium

Competition experiments were performed by adding pre-formed solutions of diisopropyloxy(η²-cyclopentene)titanium in diethyl ether to various mixtures of unsaturated compounds at low temperature, establishing the following reactivity scale: aldehyde > nitrile > ketone > terminal alkyne > internal alkyne > terminal alkene > ester, carbonate.     

Application of recoverable nanosized palladium(0) catalyst in Sonogashira reaction

In the absence of ligand, copper and amine, a recoverable nanoparticle palladium(0) catalyzed Sonogashira reaction of aryl iodides and bromides with terminal alkynes was developed. The protocol involved the use of an environmental-friendly reaction system with ethanol as the solvent, potassium carbonate as a base, and poly(vinylpyrrolidone) (PVP) supported nanosized palladium metal colloids as the catalyst. The palladium metal was recovered and recycled by a simple decantation of the reaction solution and used for eight consecutive trials without significant loss of its reactivity.     

在配位体络合体系中合成窄分布聚苯乙烯

本文报道了在RLi-配位体络合体系中阴离子聚合方法合成窄分布聚苯乙烯的研究结果.在己烷、庚烷、甲苯等溶液中合成分子量范围为10~2～10~3。的窄分布聚苯乙烯(MWD<1.10)时,以鹰爪豆矸、N,N,N’,N’-四甲基乙二胺为配位体的络合体系,聚合操作简便,效果非常好.在非极性溶剂中加一定比例的THF以后,该体系也能合成分子量范围为10~4～10~5的窄分布聚苯乙烯.     

高活性的茂基钛配合物／正丁基锂加氢催化体系的研究

考察了茂环上不同取代基及钛上阴离子配体对茂基钛配合物／正丁基锂催化体系加氢活性和稳定性的影响。在充分发挥该体系催化活性的条件下，由配合物Ｃｐ２ＴｉＣｌ２、Ｃｐ２ＴｉＦ２和Ｃｐ２Ｔｉ［ＯＣ６Ｈ３（ＣＨ３－２）Ｃｌ－４］２组成的催化体系对辛烯－１加氢的最高活性（或初活性）达到４６￣５８ｓ＾－１。     

Vibronic intensities in centrosymmetric lanthanide complex ions. I

Summary A theoretical model to calculate the vibronic intensities induced by the odd vibrational modes in centrosymmetric lanthanide complexes is developed and applied to octahedral complex ions, LnX ₆ ^3– , such as occur in the hexachloroelpasolites Cs₂NaLnCl₆. Both the crystal field and the ligand polarisation contributions are evaluated using a standard set of symmetry coordinates. For the crystal field term a truncated expansion of the intermediates states is employed rather than the more conventional closure approximation. Special care is necessary to ensure that the phases of the contributions are correctly determined since the cross-term between the ligand polarisation and crystal field contributions is signed. General equations applicable to anyf ⁿ complex ion are derived and an example of their application to the PrCl ₆ ^3– ion is given The agreement with experiment is satisfactory.     

SYNTHESIS OF ORGANOGERMANE OLIGOMERS VIA LIGAND SUBSTITUTION POLYMERIZATION FROM 1, 4-DIOXANE COMPLEX OF GERMANIUM DICHLORIDE

Some organogermanium oligomers with different side groups were synthesized via li-gand substitution polymerization from 1, 4-dioxane complex of germanium dichloride withdifferent organolithitum compounds. The oligomers were isolated through either precipi-tation from methanol or extraction using toluene with a yield of no less than 50%. Theweiglit average molecular weight (M_w) of the oligomers is ranging from 1.4×10~3 to 5.9×10~3depending on the type and alkyl length of the organolithium compounds used.     

不对称合成中手性磷配体催化剂的研究进展（I）（待续）

评述了作为配体催化剂的手性三配位及四配位磷化合物的合成及其在某些不对称的合反应中的应用。     

Reaktivität von Monophosphan-Platin(0)-Verbindungen gegenüber Schwefeldioxid

Reactivity of Monophosphine Platinum(0) Complexes with SO₂ . The addition reaction of (PPh₃)Pt(ViSi) (ViSi = {η²-H₂C?CHSiMe₂}₂O) ( 1 ) with SO₂ gives within 30 min the red SO₂ complex (PPh₃)Pt(η²-H₂C?CHSiMe₂- OSiMe₂CH?CH₂)(SO₂) ( 2 ). A reaction time of 24 h with SO₂ leads to the elimination of the ViSi ligand, and the unstable monomeric intermediate (PPh₃)Pt(SO₂) cyclo- trimerizes to the stable cluster [Pt(PPh₃)(SO₂)]₃ ( 3 ). 3 is also obtained within 30 min by the reaction of (PPh₃)Pt(C₂H₄)₂ ( 4 ) with SO₂. The crystal structure of 3 has been determined; space group P2₁/n, Z = 4, a = 1 606.1(3), b = 1 019.3(1), c = 3 624.6(5) pm, β = 93.67°, R/R_w = 0.102/0.121.     

Comparison of tridentate ligands in competition experiments for their ability to form a [Tc(CO)3] complex

In this study we have compared different ligands containing three or more hetero-atoms (N, O and/or S) with respect to their ability to form tridentate complexes with a Tc-tricarbonyl moiety. Comparison of each ligand in a competition reaction with histidine first and then with each other compound allowed to rank the ligands according to their ability of complex formation with the [^99mTc(CO)₃]⁺ precursor from diethylenetriamine (most efficient of the studied ligands) to nitrilotriacetic acid (weakest complexing properties). The results provide insight in the structural requirements for the formation of stable Tc-tricarbonyl complexes and suggest preferred combinations and arrangements of the hetero-atoms involved in the complex formation. They also give a good indication which type of ligand is most appropriate to modify biomolecules for an efficient and stable labelling with a Tc-tricarbonyl moiety.