Regioselective Cis Insertion of DMAD into Au–P Bonds: Effect of Auxiliary Ligands on the Reaction Mechanism
摘要:
The cis insertion of dimethyl acetylenedicarboxylate (DMAD, 2) into the Au-P bond of Au(SAr)(PAr'3) (1) occurs selectively at room temperature to give adduct 3, whose X-ray crystallographic analysis exhibits the predominant character of an alkenylphosphorus zwitterion complex. The first-order kinetics with respect to 1 and 2 and the large negative value of Delta S-double dagger indicate that the reaction proceeds through the coordination of 2 to 1 followed by a concerted inner-sphere nucleophilic attack of PPh3 on the coordinated triple bond. In contrast, Au(Cl)(PPh3) (4) does not react with 2 even at 60 degrees C. However, the tricoordinated 16-electron complex Au(Cl)(PPh3)(2) (5) quite successfully reacts with 2 to produce insertion product 6, demonstrating that two PPh3 ligands are required for the reaction.
A new series of bis(ene-1,2-dithiolato)tungsten(<scp>iv</scp>), -(<scp>v</scp>), -(<scp>vi</scp>) complexes as reaction centre models of tungsten enzymes: Preparation, crystal structures and spectroscopic properties
structure consisting of the bidentate LCOOMe and two oxo groups, in which π-delocalization was observed between the WVIO2 and ene-1,2-dithiolate units. The tungsten(IV) and dioxotungsten(VI) complexes are isostructural with the molybdenum counter parts. DFT calculation study of the WVIO(S) complex has indicated that the WS bond of 2.2 Å is close to the bond length between the tungsten centre and ambiguously
碳甲氧基取代的二硫辛烯配体(L COOMe)使我们能够开发一系列新的双(烯-1,2-二硫代Lato)钨配合物,包括W IV O,W IV(OSiBuPh 2),W VI O 2,W VI O( OSiBuPh 2)和W VI O(S)核心结构。通过使用这些钨配合物,已经对结构,光谱性质和反应性进行了末端单齿配体效应的系统研究。钨配合物的结构和光谱性质也已与相同配体配位的钼配合物的结构和光谱性质进行了比较,以研究金属离子的作用(W与Mo)。钨(IV)配合物的X射线晶体学分析表明,钨中心采用扭曲的方锥几何形状,并带有烯-1,2-二硫醇酯形式的二硫代烯配体。另一方面,二氧钨(VI)配合物表现出由双齿L COOMe和两个氧代基团组成的八面体结构,其中在W VI O 2和烯1,2-二硫代酸酯单元之间观察到π-离域化。钨(IV)和二氧钨(VI)配合物与钼的对应部分是同构的。W VI O(S)配合物的DFT计算研究表明,W2
Solvent-free photochemical decomposition of sulfur hexafluoride by phosphines: formation of difluorophosphoranes as versatile fluorination reagents
photochemical reaction of SF6 with phosphines, which selectively produces difluorophosphoranes and phosphine sulfides. Computational and experimental studies show that the π(Ar) → σ*(SF6) charge-transfer excitation of a preformed R3P⋯SF6 complex is the initial activation step. Using triphenylphosphine, the decomposition of SF6 was carried out in a solvent-free, scalable process, giving a 3 : 1 mixture of
SF 6的化学活化因其可能用作化学合成中廉价且安全的试剂而引起了相当多的关注。当与技术应用后强效温室气体的处理相结合时,这种过程变得特别有吸引力。在此,我们报道了SF 6与膦的光化学反应,该反应选择性地产生二氟正膦和硫化膦。计算和实验研究表明,预先形成的 R 3 PSF 6复合物的 π(Ar) → σ*(SF 6 ) 电荷转移激发是初始激活步骤。用三苯膦,分解SF 6在无溶剂、可扩展的过程中进行,得到二氟三苯基正膦和三苯基硫化膦 (TPP-Fluor) 的 3:1 混合物,用于醇和羧酸的脱氧氟化以及制备常见的六氟磷酸盐。
Pd-Catalyzed P–C Cross-Coupling Reactions for Versatile Triarylphosphine Synthesis
Practical and versatile syntheses of tertiary phosphine derivatives have been achieved by palladium-catalyzed deformylative P-C cross-coupling reactions of hydroxymethylphosphine derivatives. Sequential couplings of orthogonally protected precursors provide a simple and practical route toward a variety of tertiary phosphine derivatives having aryl substituents in any combination.
Hall, C. Dennis; Tweedy, Bruce R.; Kayhanian, Robert, Journal of the Chemical Society. Perkin transactions II, 1992, # 2, p. 775 - 779
作者:Hall, C. Dennis、Tweedy, Bruce R.、Kayhanian, Robert、Lloyd, John R.