279 research outputs found
Chelate Palladium(II) Complexes with Saturated N-Phosphanyl-N-Heterocyclic Carbene Ligands: Synthesis and Catalysis
No full textPalladium(II) Complexes with N-Phosphanyl-N-heterocyclic Carbenes as Catalysts for Intermolecular Alkyne Hydroaminations
No full textThe catalytic potential of palladium(II) complexes with chelating N-phosphanyl-N-heterocyclic carbenes (NHCPs) featuring a saturated imidazolin-2-ylidene or tetrahydropyrimid-2-ylidene ring has been investigated in intermolecular alkyne hydroamination reactions. The complexes were found to be among the most active Pd-based catalysts for these processes and to enable the use of low reaction temperatures (40°C) and of solventless conditions. The Pd complexes require activation by two equivalents of a silver salt to remove chlorido ligands from the metal coordination sphere; they can however also be presynthesized in active form, which allows their use under silver-free conditions. The hydroamination reaction was found to efficiently proceed with terminal alkynes and different ring substituted, primary arylamine substrates
PdIIComplexes with N-(Diadamantylphosphanyl)diaminocarbene and Related Ligands: Synthesis and Catalytic Applications in Intermolecular Alkyne Hydroaminations
No full textA new N-diadamantylphosphanyldiaminocarbene 5 is prepared, isolated, and characterized. The carbene appears to be much more stable than previously reported di-tert-butyl congeners. The molecular structure of the carbene is determined by X-ray diffraction analysis. A new (diisopropyl-amino)(diadamantylphosphanyl) carbene 8 is also prepared in situ, but not isolated, since in this case, the adamantyl groups do not render the carbene more stable, with respect to previously known carbenes with di-tert-butyl substitution. Carbene 8 reacts in situ with phenylazide to give iminophosphane 9, which is also accessible from carbene 5 upon rearrangement under heating. Stable chelate Pd-II complexes are synthesized using both carbene 5 and iminophosphane 9 as ligands. The complex with ligand 9 displays very promising catalytic performance in the intermolecular hydroamination of alkynes with primary arylamines
Palladium(ii) complexes with chelating N-phosphanyl acyclic diaminocarbenes: Synthesis, characterization and catalytic performance in Suzuki couplings
No full text
Diffusion approximations of the geometric Markov renewal processes and option price formulas
No full textWe consider the geometric Markov renewal processes as a model for a securitymarket and study this processes in a diffusion approximation scheme. Weak convergenceanalysis and rates of convergence of ergodic geometric Markov renewal processes in diffusionscheme are presented. We present European call option pricing formulas in the case ofergodic, double-averaged, and merged diffusion geometric Markov renewal processes.Source type: Electronic(1
N-phosphanyl-imidazolin-2-ylidenes: Novel stable carbenes as bidentate ligands for late transition metals
No full textN-phosphorylated, N-heterocyclic carbenes (NHC) based on the imidazoline skeleton have been prepared for the first time. The free carbenes feature good stability and in best cases they can be stored in the solid state for months at ambient temperature without decomposition. The carbenes are capable of acting as ligands towards late transition metal centers such as silver(I). The resulting complexes are stable and can be employed as reagents for the preparation of complexes of other group 11 metals upon transmetallation. The complexes, one carbene ligand and related compounds have all been structurally characterized
Neutral dinuclear gold(I) complexes with N-phosphanyl, N-heterocyclic carbenes (NHCPs)
No full textNeutral dinuclear gold(I) complexes having general formula [Au2Cl2(NHCP)] (NHCP = N-phosphanyl N-heterocyclic carbene) have been synthesized by two different synthetic procedures: i) transmetalation of the NHCP ligand from the corresponding dinuclear silver(I) complex; ii) deprotonation of the corresponding N-phosphanyl azolium/tetrahydropyrimidinium salt in the presence of the gold(I) precursor. Interestingly, although the silver complexes are invariably dinuclear dicationic species of formula [Ag2(NHCP)2](OTf)2, both stoichiometries [Au2(NHCP)2](OTf)2 and [Au2Cl2(NHCP)] are potentially accessible with gold. Preference for either stoichiometry is dictated by the steric properties of the NHCP ligand as well as by a proper choice of the experimental conditions. On the other hand, preparation of copper(I) compounds with [Cu2Cl2(NHCP)] stoichiometry leads to product mixtures and has not led up to now to pure neutral compounds. Both the silver(I) and gold(I) complexes have been structurally characterized
Stable N‐Phosphorylated 1,2,4-Triazol-5-ylidenes: Novel Ligands for Metal Complexes
No full textSynthetic routes to novel N-phosphorylated
1,2,4-triazolium salts have been developed. Treatment of the
specified salts with strong base produces new stable Nphosphorylated 1,2,4-triazol-5-ylidenes, which add Se in two
stages (first at the carbene carbon and then at phosphorus)
and rearrange to C-phosphorylated triazoles with heating. The capacity of such N-phosphorylated triazol-5-ylidenes to act as
bidentate ligands toward transition-metal centers has also been demonstrated; in particular, the formation of two dinuclear silver
carbene complexes is described herein. The structures of one representative carbene and of one carbene complex were
determined by an X-ray study
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