Organometallic Chemistry & Catalysis

Catalysis by metallocorroles is emphasized by the group of Zeev Gross for the following purposes: a) enzyme-like asymmetric catalysis with proteins as the chirality inducing motif; b) decomposition of reactive oxygen & nitrogen species for treating diseases affected by oxidative stress; c) photodynamic inactivation of cancer cells and harmful microorganisms; d) electrochemical reduction of small molecules/ions for energy-relevant processes; and e) various photo-induced reactions. Regarding the latter, recent focus is on alternative energy and fuel cells, which includes the development of new chromophores for dye sensitized solar cells, the design of catalysts for the 4-electron/4-protons reduction of oxygen to water, the hydrogen evolution reaction, and for water oxidation (the oxygen evolution reaction). Another relevant approach is to take advantage of the strong reducing power of metallocorroles for the activation of small molecules/ions like carbon dioxide and halides.

The Marek group is concerned with the design and development of new and efficient stereo- and enantioselective strategies for the synthesis of important complex molecular structures. We are particularly interested in developing carbon-carbon bond forming processes, which efficiently create multiple stereocenters in a single-pot operation. Deep understanding of reaction mechanisms gives insight into the origins of chemo- and stereoselectivity, and governs optimization towards the most efficient and general protocols for our methodologies. Our vision is that we should provide an answer to challenging synthetic problems but it has to be coupled with unique efficiency and elegance.

The high efficiency and selectivity achieved by enzymatic catalysis is largely due to the cooperativity between a metal center and the functional organic molecules located at its surrounding folds.
Capitalizing on this notion, the Maayan’s group is developing biomimetic cooperative catalysts that are based on peptidomimetic oligomers called peptoids, which their versatile backbones include two or more catalytic and co-catalytic groups. These peptoids act as intramolecular cooperative catalysts in various oxidation transformations including aerobic oxidation of alcohols and electrocatalytic water oxidation, demonstrating improved catalytic efficiency.

The research in Eisen group deals with two major topics:
1) One of our main research topics deal with the synthesis of advanced polymers by novel octahedral homogeneous catalysts This research has focuses on the synthesis, characterization, and the catalytic activity studies for a unique type of coordinative unsaturated group (IV) (Ti, Zr, Hf), “cationic” complexes containing electrophilic ancillary ligands. The types of ancillary ligands, which were pursued for the preparation of these cationic complexes, were those containing substituted heteroallylic, acetylacetonato, dikitiminate and imidazoline-2-iminato ancillary ligands . In all cases the ligand motif is bulky enough to prevent solvent coordination. The research is directed in three major simultaneous pathways: (a) The understanding of the electronic effects of the different ancillary ligands on the metal reactivity. (b) The tailoring of chiral and achiral ancillary ligands and chiral or racemic mixtures of complexes, to design a specific stereoregular polymerization of a–olefins and design novel chemical transformations to obtain new advanced type of materials. (c) The thoroughly characterization of the new polymeric materials to allow the design of new catalysts for improved polymer properties. The achievement obtained in the synthesis and the application of these new types of coordinative unsaturated complexes are a subject of International basic scientific and technological significance for the novel, clever and unique preparation of new materials.
2) The organometallic chemistry of organoactinides is reaching a high level of sophistication in regards to the basic understanding on the mechanisms by which these complexes operate and have been corroborated with bond disruption enthalpies studies for diverse types of complexes. Our research with organoactinide complexes target their use as catalytic key intermediates in designed catalytic processes with large academic interest. Thus, oriented towards the use of organoimido complexes of actinides to catalyze the anti-Markovnikov addition of an amine to an alkyne to directly synthesized imines. In addition, we have use this complexes for the linear oligomerization of terminal alkynes or the hydrosilylation of terminal alkynes. During the last years, our group has developed new catalytic techniques for the use of actinides in energy demanding catalytic transformations containing oxygen moieties, a myth that was believed to be impossible until few years ago. The unprecedented addition of alcohols to carbodiimides mediated by actinide complexes was successfully realized. This represents a rare example of thorium-catalyzed transformations of an alcoholic substrate, and the first example of uranium complexes showing catalytic reactivity with alcohols. Using the uranium and thorium-amides, alcohol additions to unsaturated carbon-nitrogen bonds are achieved in short reaction times with excellent selectivities and high to excellent yields. Computational studies, supported by experimental thermodynamic data, reveal the modes of bonding in the profile of the reaction, which allow the system to overcome the high barrier of scission of the actinide-oxygen bond.

The research of Apeloig’s group concentrates on main group chemistry, mostly organosilicon chemistry. Emphasis is mainly on the synthesis and properties of novel low-coordination compounds such as doubly- and triply-bonded silicon compounds, such as R2E=E’R2, E=C, Si, Ge, Sn, Pb and various reactive intermediates such as silyl and silavinyl anions, silylenes, etc. Novel reagents, such as metallosilanes, dimetallosilanes and metalosilavinylsilanes and are developed. Novel methods for the activation of Si-H bonds, an important industrial process, are being developed.

Despite recent advances in organometallic and inorganic chemistry, the activation and conversion of small molecules under ambient conditions remains challenging. In our lab

, Graham de Ruiter,  we try to solve these challenges by designing new inorganic/organometallic materials that are able to use photons and electrons in order to convert these small molecules (e.g. CO2, N2, O2) into value added chemicals.

Our approach focusses on synthesizing novel transition metal complexes that – upon light irradiation – are able to:

(i) Change their chemical environment
(ii) Utilize photo-redox process to generate highly oxidizing/reducing metal centers

By self-assembling these metal complexes unto solid surfaces, we can use the superior properties of inorganic and semiconductor materials – in light-harvesting and electron transfer – to fabricate new supramolecular architectures that can be used in catalysis and small molecule activation. The physicochemical properties of these newly synthesized materials will be investigated with a wide variety of analytical techniques including spectroelectrochemistry.

Other research directions will build upon our experience in small molecule activation, and use these principles to develop a new class of organometallic polymers that relies the activation of N2.