Entwicklung neuer Ruthenium-Metathese-Katalysatoren und ihre Anwendung in der alternierenden ROMP
Within this Ph.D. work studies were carried out for the development of new ruthenium metathesis catalysts and their application in the alternating ring opening metathesis polymerisation (alt-ROMP). The first part of this Ph.D. study was occupied with the design of electronically modified ruthenium indenylidene complexes. For this purpose a multitude of diversely substituted propargyl alcohols were synthesised and converted with RuCl2(PPh3)3 to yield the corresponding ruthenium indenylidene
... m indenylidene catalysts. Thereby, only not separable product mixtures could be isolated so there was no possibility to produce pure modified ruthenium indenylidene complexes. Therefore, the synthetic route was changed to obtain the corresponding electronically modified ruthenium allenylidene complexes. These pre-catalysts were tested in their ring closing metathesis (RCM) efficiency and activity of diallyltosylamide and diethyldiallylmalonate. The second part of this Ph.D. work was dedicated at the generalisation of the concept of alternating ROMP. Instead, different unsymmetrical N-heterocyclic carbene ruthenium initiators were tested with phosphin or pyridine ligands. The sterical hindrance of the saturated, unsymmetrical NHCs was varied to verify this concept of alternating copolymerisation via metathesis, whereas the mesityl group of the NHC was retained. Furthermore the chiral centre of the reported Grubbs NHC initiator with a 1-phenylethyl side group was switched-off by removal respectively inserting of the methyl group so that the influence of the chiral centre on the sequence selective copolymerisation could be estimated. In addition the efficiency of the ruthenium catalysts in the alternating ROMP was increased by studies of the reaction kinetics. In exchanging a phosphin with a pyridine ligand the reaction time of one hour was decreased to one minute and no shifting of yield and selectivity was observed.