The ?Nickel Effect?

Breuil PA, Olivier-Bourbigou H, Braunstein P. Synthesis and characterization of oxygen-functionalised-NHC silver(i) complexes and NHC transmetallation to nickel(ii)

New silver(i) complexes bearing alcohol- or ether-functionalized NHCs were synthesized and characterized by X-ray diffraction. Their NHC transmetallation ability was assessed and gave rise to a Ni(ii) bis(NHC) complex in the case of the ether-functionalisation.

An approach to mimicking the sesquiterpene cyclase phase by nickel-promoted diene/alkyne cooligomerization

Artificially mimicking the cyclase phase of terpene biosynthesis inspires the invention of new methodologies, since working with carbogenic frameworks containing minimal functionality limits the chemist's toolbox of synthetic strategies. For example, the construction of terpene skeletons from five-carbon building blocks would be an exciting pathway to mimic in the laboratory. Nature oligomerizes, cyclizes, and then oxidizes γ,γ-dimethylallyl pyrophosphate (DMAPP) and isopentenyl pyrophosphate (IPP) to all of the known terpenes. Starting from isoprene, the goal of this work was to mimic Nature's approach for rapidly building molecular complexity. In principle, the controlled oligomerization of isoprene would drastically simplify the synthesis of terpenes used in the medicine, perfumery, flavor, and materials industries. This article delineates our extensive efforts to cooligomerize isoprene or butadiene with alkynes in a controlled fashion by zerovalent nickel catalysis building off the classic studies by Wilke and co-workers.

A simple, multidimensional approach to high-throughput discovery of catalytic reactions

Transition metal complexes catalyze many important reactions that are employed in medicine, materials science, and energy production. Although high-throughput methods for the discovery of catalysts that would mirror related approaches for the discovery of medicinally active compounds have been the focus of much attention, these methods have not been sufficiently general or accessible to typical synthetic laboratories to be adopted widely. We report a method to evaluate a broad range of catalysts for potential coupling reactions with the use of simple laboratory equipment. Specifically, we screen an array of catalysts and ligands with a diverse mixture of substrates and then use mass spectrometry to identify reaction products that, by design, exceed the mass of any single substrate. With this method, we discovered a copper-catalyzed alkyne hydroamination and two nickel-catalyzed hydroarylation reactions, each of which displays excellent functional-group tolerance.

Transformation of carbon dioxide with homogeneous transition-metal catalysts: a molecular solution to a global challenge?

A plethora of methods have been developed over the years so that carbon dioxide can be used as a reactant in organic synthesis. Given the abundance of this compound, its utilization in synthetic chemistry, particularly on an industrial scale, is still at a rather low level. In the last 35 years, considerable research has been performed to find catalytic routes to transform CO(2) into carboxylic acids, esters, lactones, and polymers in an economic way. This Review presents an overview of the available homogeneous catalytic routes that use carbon dioxide as a C(1) carbon source for the synthesis of industrial products as well as fine chemicals.

Designing late-transition metal catalysts for olefin insertion polymerization and copolymerization

The innovation of polyolefin with unique architecture, composition and topology continues to inspire polymer chemists. An exciting recent direction in the polyolefin field is the design of new catalysts based on late-transition metals. In this review, we highlight recent developments in rationally designing late-transition metal catalysts for olefin polymerization. The examples described in this review showcase the power of the design of well-defined late-metal catalysts for tailored polyolefin synthesis, which may usher in a new era in the polymer industry.

The Electronic Structure of the Tris(ethylene) Complexes [M(C2H4)3] (M=Ni, Pd, and Pt): A Combined Experimental and Theoretical Study

In this article we analyze in detail the electronic properties of the D(3h)-symmetric tris(ethylene) complexes of nickel, palladium, and platinum ([M(C(2)H(4))(3)] M=Ni, Pd, Pt). In the case of [Pd(C(2)H(4))(3)] the analysis is based on new experimental IR and Raman spectra for the matrix-isolated molecules and in all cases on the results of quantum-chemical (DFT) calculations. The experimental spectra collected for [Pd(C(2)H(4))(3)] provide evidence for several previously unobserved vibrational modes, including the in-phase and out-of-phase nu(C-C) and delta(CH(2)) modes, and the in-phase nu(M-C) mode. Special consideration is given to possible inter-ligand interactions. The interaction force constant f(CC,CC) between two C(2)H(4) ligands can be directly estimated from the spectra, and its very small value (0.002 N m(-1)) indicates the absence of any significant inter-ligand interaction. An analysis of the topology of the theoretical electron density distribution, rho(r), and the corresponding Laplacian, nabla(2)rho(r), for [Pd(C(2)H(4))(3)] and its lighter and heavier homologues [Ni(C(2)H(4))(3)] and [Pt(C(2)H(4))(3)], respectively, is in full agreement with the conclusions drawn from the experimental results. The combined experimental and quantum-chemical results provide detailed insights in the electronic properties of these prototypical ethylene complexes.

A structurally characterized Ni–Al methyl-bridged complex with catalytic ethylene oligomerization activity

A bimetallic Ni-Al (2.5087(15) A) complex with an agostic alpha-C-H, [eta-C5H4CH=N(C6F5)]Fe[eta-C5H4PPh2]Ni(AlMe3), has been isolated and crystallographically established. The complex is active towards ethylene oligomerization/polymerization under moderate conditions.