19191-03-8Relevant articles and documents
Inner-Sphere versus Outer-Sphere Coordination of BF4- in a NHC-Gold(I) Complex
Veenboer, Richard M. P.,Collado, Alba,Dupuy, Stéphanie,Lebl, Tomas,Falivene, Laura,Cavallo, Luigi,Cordes, David B.,Slawin, Alexandra M. Z.,Cazin, Catherine S. J.,Nolan, Steven P.
, p. 2861 - 2869 (2017)
The role of counterions in chemistry mediated by gold complexes stretches much further than merely providing charge balance to cationic gold species. Interplay between their basicities and coordination strengths influences interactions with both the gold center and substrates in catalysis. Actual monogold(I) active species are generally believed to be monocoordinated species, formed from the abstraction or the decoordination of a second ligand from precursor complexes, but only a small amount of experimental evidence exists to underpin the existence of these transient species. The formation of a bench-stable neutral IPrCl-gold(I) tetrafluoroborate complex is reported herein. Experimental studies by X-ray diffraction analysis and NMR spectroscopy and theoretical studies by DFT calculations were conducted to determine the composition, structure, and behavior of this complex. The absence of an auxiliary ligand resulted in inner-sphere coordination of the counterion in the solid state. In solution, an equilibrium between two conformations was found with the counterion occupying inner-sphere and outer-sphere positions, respectively. Stoichiometric and catalytic reactivity studies with the tetrafluoroborate complex have been conducted. These confirmed the lability of the inner-sphere coordinating counterion that gives the IPrCl-gold(I) fragment behavior similar to that of related systems.
Palladium-Catalyzed Reductive Cross-Coupling Reaction of Aryl Chromium(0) Fischer Carbene Complexes with Aryl Iodides
Wang, Kang,Lu, Yu,Hu, Fangdong,Yang, Jinghui,Zhang, Yan,Wang, Zhi-Xiang,Wang, Jianbo
supporting information, p. 1 - 10 (2018/01/17)
The first palladium-catalyzed reductive cross-couplings of aryl chromium(0) carbene complexes with aryl iodides have been realized. This coupling reaction shows excellent functional group tolerance and high efficiency. Mechanistically, aryl chromium(0) carbene complexes undergo transmetalation with arylpalladium species to generate palladium(II) carbene intermediates, which is followed by migratory insertion. The catalytic cycle is then completed by hydrogen transfer and reductive elimination. Consistent with the mechanistic hypothesis, density functional theory (DFT) calculations support the involvement of a palladium carbene intermediate, and carbene migratory insertion is a facile step with an energy barrier of 5.1 kcal/mol. The carbene transfer step and the hydrogen transfer step are confirmed as the rate-limiting steps in the catalytic cycle.
A parahydrogen based NMR study of Pt catalysed alkyne hydrogenation
Boutain, Marie,Duckett, Simon B.,Dunne, John P.,Godard, Cyril,Hernandez, Jose M.,Holmes, A. Jonathan,Khazal, Iman G.,Lopez-Serrano, Joaquin
body text, p. 3495 - 3500 (2010/07/03)
A parahydrogen based NMR study of the platinum(ii) bis-phosphine triflate catalysed hydrogenation of alkynes in methanol reveals that platinum bis-phosphine alkyl cations and methanol functionalised platinum bis-phosphine alkylether cations, are responsible for the observed alkene and vinylether products.
