The bis-carbene precursor, 1, gives a thermally very robust Pd(II) catalyst for Heck coupling that maintains activity even in boiling diethylacetamide (bp 184 °C) air.

N-heterocyclic carbene-based heterometallic complexes have emerged as useful multicatalysts for tandem reactions.

The synthesis and X-ray crystallographic characterization of a Pd complex (3) with rigid C,N,C-tridentate pincer carbene ligand are described. At high temperatures (165 °C) it is an active robust catalyst in the Heck reaction. Complex 3 gives some highest turnover numbers yet reported for coupling aryl chlorides. Time dependence, reuse, reaction conditions discussed 3. Data F- as base did not support Shaw's mechanism. Suzuki Sonogashira reactions also catalyzed by palladium 5, containing...

Ru(CNC)(CO)Br2 and [Ru(CNC)2](PF6)2 complexes (CNC = 2,6-bis(butylimidazol-2-ylidene)pyridine) are accessible via a simple synthesis. The crystal structures of both have been determined by means X-ray diffractometry. catalytic activity the precursor toward hydrogen transfer from alcohols to ketones oxidation olefins confirms versatility this new phosphine-free Ru catalyst.

Chelating rhodium(III) carbene complexes are accessible via a simple synthesis and catalytically active for hydrogen transfer from alcohols to ketones imines.

Chelating bis(imidazolium) salts having (CH2)n chains of different lengths (n = 1−4) linking the diazole rings show very large reactivity differences on metalation with [(cod)RhCl]2. Long linkers favor a square-planar Rh(I) product, while short octahedral Rh(III). We ascribe origin effect to restricted rotation highly sterically anisotropic and preferred orientations these as n changes. Defining x y axes Rh−carbene bond directions, we find that tend be oriented close xy plane. This tends...

The ligand 1,2,4-trimethyl-triazolyl-diylidene has been used for the preparation of a series three iridium/palladium heterometallic complexes that have fully characterized. presence two different metals allows tandem processes to be designed by combining reactions are typically catalyzed Ir and Pd. Three studied: dehalogenation/transfer hydrogenation haloacetophenones, Suzuki-coupling/transfer p-bromoacetophenone, Suzuki-coupling/α-alkylation p-bromoacetophenone. All yielded excellent...

The immobilization of a homogeneous catalyst onto solid surface is one the major challenges in catalysis, because it may facilitate separation and reaction products also give rise to reutilization multiple subsequent cycles. Noncovalent interactions between support are arising as interesting alternatives more widely used covalent interactions, they avoid functionalization both surface, which turn lead modification inherent properties catalyst. However, some other problems arise, such...

The reaction of 1,2,4-trimethyltriazolium tetrafluoroborate ([LH2](BF4)2) with several metal precursors provides a series homo- and heterodimetallic compounds Rh Ir. [LH2](BF4)2 [Cp*IrCl2]2 in the presence NaH MeOH yields monocarbene complex [Cp*Ir(LH)Cl2](BF4), which is very convenient synthon to preparation species through deprotonation remaining NCHN group. Three crystal structures dimetallic di-iridium(III), iridium(III)/iridium(I), iridium(III)/rhodium(I) are described. complexes...

A new tandem catalytic process has been studied for a heterodimetallic complex containing both iridium and palladium fragments connected by 1,2,4-trimethyltriazolyldiylidene ligand. The implies the unprecedented preparation of imines from direct reaction nitroarenes primary alcohols. global comprises following steps: 1) reduction nitroarene to an amine, 2) oxidation alcohol aldehyde, 3) condensation aldehyde amine form corresponding imine. is promoted fragment, while nitro group facilitated...

Abstract The demand for nanocomposites of graphene and carbonaceous materials decorated with metallic nanoparticles is increasing on account their applications in science technology. Traditionally, the production graphene-metal assemblies achieved by non-environmentally friendly reduction salts suspensions. However, precursor residues during nanoparticle growth may reduce surface activity promote cross-chemical undesired effects. In this work we present a laser-based alternative to...

Abstract A series of new bridging, chelating and pincer N ‐heterocyclic carbenes Rh I III have been obtained under mild conditions. The compounds fully characterised their crystal structures determined. chelate‐pincer coordination the ligands means that stability these is significantly greater than other carbene complexes Rh. tested in catalytic reactions such as hydrogen transfer from alcohols to ketones, hydrosilylation terminal olefins alkynes; they show a high activity for both...

Double trouble: A series of complexes rhodium and iridium has been obtained with a triazolediylidene ligand, which behaves as an extraordinarily versatile Janus-type ligand to form dinuclear complexes. The showed improved catalytic properties over their mononuclear counterparts. picture shows diiridium complex 1,2,4-trimethyltriazole-3,5-diylidene (Ir gray, C white, N blue, O red, Cl green).

A set of three different NHC-Pd-pyridine complexes (NHC = 1,2,4-trimethyltriazolyldiylidene, 1,3-dimethylimidazolylidene, and 1,4-dimethyltriazolylidene) have been prepared fully characterized. The X-ray molecular structures two the are reported. tested in a series reactions between o-hydroxyaryl halides phenylacetylene to afford benzofurans, tandem process that comprises Sonogashira coupling followed by cyclic hydroalkoxylation. All catalysts afforded excellent yields final products when...

Four Ir(I) and Ir(III) N-heterocyclic carbene (NHC) based complexes with 3,4,5-trimethoxybenzyl N-substituents have been obtained fully characterized. The new used as catalysts in the reduction of aldehydes ketones glycerol, their activities compared to those shown by other NHC-complexes previously reported. reactions were carried out under oil bath heating, a detailed comparative study has using microwave (MW) ultrasound (US) activation. proved be most efficient ketones, while are more...

The co-immobilization of palladium and ruthenium complexes with pyrene-tagged N-heterocyclic carbene ligands onto reduced graphene oxide allows the formation a highly efficient catalyst for hydrodefluorination series fluoroarenes. This procedure constitutes an easy one-pot preparation materials homogeneously distributed polymetallic catalysts. catalytic system can be recycled up to 12 times without measurable loss activity. activity is attributed synergistic action two metals.

A triazolyl-di-ylidene ligand has been used for the preparation of a homodimetallic complex gold, and heterodimetallic compound gold iridium. Both complexes have fully characterized their molecular structures determined by means X-ray diffraction. The catalytic properties these two evaluated in reduction nitroarenes transfer hydrogenation using primary alcohols. afford different reaction products; whereas Au(I)-Au(I) catalyst yields hydroxylamine, Ir(III)-Au(I) facilitates formation an imine.

The catalytic dehydrogenative coupling of silanes and alcohols represents a convenient process to produce hydrogen on demand. catalyst, an iridium complex the formula [IrCp*(Cl)2(NHC)] containing N-heterocyclic carbene (NHC) ligand functionalized with pyrene tag, catalyzes efficiently reaction at room temperature producing H2 quantitatively within few minutes. As result, 1,4-disilabutane methanol enables effective storage capacity 4.3 wt % that is as high contained in dehydrogenation formic...

An effective visible-light-promoted iridium(III)-catalyzed hydrogen production from N-heterocycles is described. A single iridium complex constitutes the photocatalytic system playing a dual task, harvesting visible-light and facilitating C-H cleavage H2 formation at room temperature without additives. The presence of chelating C-N ligand combining mesoionic carbene along with an amido functionality in IrIII essential to attain transformation. Furthermore, also efficient catalyst for thermal...

A new dirhodium(I) bisimidazolium-carbene complex has been obtained and fully characterized by means of NMR spectroscopy single-crystal X-ray diffraction. The used as catalyst in hydroformylation reactions, showing selectivity on the branched aldehyde. High-pressure provides evidence that dinuclear unit is maintained under catalytic conditions.

The metalation of a series C2-Me-substituted monoimidazolium and bisimidazolium salts to [Cp*IrCl2]2 is described. reaction the salt provides species Cp*Ir(aNHC)Cl2, in which NHC shows an abnormal coordination mode. use different patterns depending on linker length between two azolium rings. For methylene-linked salt, only compound obtained unusual type chelating ligand coordinated through methylene group resulting from CH activation C2-Me group. ethylene-linked similar product obtained,...