Anita Leitgeb

The Influence of Phosphane Ligands on the Versatility of Ruthenium–Indenylidene Complexes in Metathesis

The aim of the present study is to develop readily available and stable pre-catalysts that could be easily prepared on large scale from simple starting materials. Based on the hypothesis that substitution of classical PCy(3) with phosphanes of varying electron-donating properties could be a straightforward manner to improve catalytic activity, a methodical study dealing with the effect of phosphane fine-tuning in ruthenium-indenylidene catalysts was performed. Challenged to establish how the electronic properties of para-substituted phosphane ligands translate into catalyst activity, the versatile behaviour of these new ruthenium-indenylidene complexes was investigated for a number of metathesis reactions.

Two commercially available initiators for the retarded ring-opening metathesis polymerization of dicyclopentadiene

Abstract The highly cross-linked thermoset poly(dicyclopentadiene) (pDCPD) is produced by ring-opening metathesis polymerization and has become an important material for many high-impact applications. Herein, the utility of two less common, yet commercially available ruthenium-based initiators M2 and M22 is disclosed for the polymerization of dicyclopentadiene and compared with the second generation Grubbs catalyst G2. Both initiators are suited to produce pDCPD pieces in high quality (as revealed from mechanical properties of test specimen) and offer a distinctly longer processing window than the reference initiator G2.Graphical Abstract

On the isomerization of a trans-dichloro to a cis-dichloro amide-chelated ruthenium benzylidene complex and the catalytic scope of these species in olefin metathesis

Upon comparative NMR spectroscopy studies, the isomerization of newly disclosed dichloro [κ2(C,O)-2-(N-propylaminocarbonyl)benzylidene][1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene]ruthenium from trans-dichloro configuration (SPY-5-31) to its thermodynamically more favored cis-dichloro derivative (with SPY-5-34 stereochemistry) was found to proceed via dissociation of one chloride ligand to form an intermediate cationic species. Furthermore, the performance of the trans- and the cis-dichloro derivatives as catalysts in ring-closing metathesis and as initiators in ring-opening metathesis polymerization was studied.Graphical abstract

N -Heterocyclic Carbene Complexes in Olefin Metathesis

Olefin metathesis is now a synthetic tool found ubiquitously in various fields involving synthesis. Of its many variations, three are prominently used: (1) catalytic ring closing metathesis (RCM) is an extremely powerful method for the construction of carbon-carbon double bonds in organic chemistry; (2) ring opening metathesis polymerisation (ROMP) where polymers are formed by use of the energy released from cyclic strain; and (3) cross metathesis (CM) where non-cyclic partners are coupled through C–C double bond formation. These important transformations and variations on these themes mediated by second generation ruthenium complexes bearing a NHC ligand will be presented in the following sections.