Phosphines carbenes

Dimesitylimidazolium chloride in the presence of potassium tert-butylate reacts with [RuCl2(PCy3)2(=CHPh)] or [RuCl2(PCy3)2(=CHCH=CMe2)] to yield the mixed phosphine-carbene complexes [RuCL(L)(PCy3)(=CHPh)] or... 

Ligand A anionic (e.g., halides, pseudohalides, alkyl, aryl, thiolate, alkoxide) ligand N neutral (e.g., amines, imines, phosphines, carbenes, nitriles, isonitriles, NO, CO) ligand C cationic (e.g., NO+)... 

Scheme 17. Synthesis of dicarbonyl(phosphine)carbene complexes by means of the benzannulation reaction.

Fig. 12) [91 ]. This phosphine-carbene ligand has been used in the nickel catalyzed hydroamination of acrylonitrile derivatives [92]. 

Fig. 13 Iridium complexes containing a chiral phosphine-carbene ligand...

QCqmlfPFg] [C4C1im][Tf2N] Pd-phosphine carbene complex Pr3N 130-150 °C. Arylation of butyl acrylate with iodobenzene in a microflow-system with continuous recycling of the ionic liquid-catalyst phase product extracted with hexane. [77]... 

The anions generated from tetracaibonyl(phosphine) carbene complexes are more reactive in their reactions with organic electrophiles. This is consistent with the observation that the p/iTa of the methyl pentacarbonyl complex (88a) is increased by six orders of magnitude when one of the carbon monoxi ligands is replaced with tributylphosphine. The anion generated fr-om (106) will give good yields of alkylated products with simple alkyl halides such as ethyl bromide however, dialkylation is still a serious side reaction. It has been reported that both pentacarbonyl and tetracarbonyl(phosphine) complexes can be efficiently monoalkylated with alkyl triflates (primary and secondary). The anion (89) for example, can be monoalkyated with the 3-butenyl triflate in 80% yield. ... 

Ylide formation by capture of electrophilic carbenes with tertiary phosphines has been shown to be a symmetry-breaking allowed pathway. The reverse process, dissociation of a phosphonium ylide into carbene and phosphine, is in agreement with the concept of phosphonium ylides as phosphine-carbene complexes."... 

The Mizoroki-Heck reaction is a subtle and complex reaction which involves a great variety of intermediate palladium complexes. The four main steps proposed by Heck (oxidative addition, alkene insertion, )3-hydride elimination and reductive elimination) have been confirmed. However, they involved a considerable number of different Pd(0) and Pd(Il) intermediates whose structure and reactivity depend on the experimental conditions, namely the catalytic precursor (Pd(0) complexes, Pd(OAc)2, palladacycles), the Ugand (mono- or bis-phosphines, carbenes, bulky monophosphines), the additives (hahdes, acetates), the aryl derivatives (ArX, ArOTf), the alkenes (electron-rich versus electron-deficient ones), which may also be ligands for Pd(0) complexes, and at least the base, which can play a... 

The family of ruthenium(NHC)(phosphine) complexes also includes chelating NHC/phosphine ligands. In a recent example by Hofmann [59], a ruthenium-indenylidene complex was prepared in 60% yield from 5 and the free phosphine-carbene ligand 46 in toluene at 80 °C. In this, the chelate forces the carbene and phosphine ligands into a cis position (Scheme 14.20). No evaluation ofthe catalytic activity of complex 47 in olefin metathesis was reported. 

Caddick and Cloke reported similar exchange reactions as early as 2001. Bis-carbene Pd complexes were reacted with phosphines resulting in displacement of the carbene under surprisingly mild conditions. In the case of P(u-tolyl)3, an equilibrium between the mixed phosphine carbene complex and the bis carbene complex was established at 60 °C (Equation (3.10)). ""... 

Scheme 5.12 Synthesis of phosphine-carbene rhodium complexes...

Scheme 5.15 Synthesis of phosphine-carbene palladium complexes 23 and 24...

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