Roman Kolly

Synthesis and reactivity of novel ruthenium carbene catalysts. X-ray structures of [RuCl2(CHSC6H5)(PiPr3)2] and [RuCl2(CHCH2CH2-C,N-2-C5H4N)(PiPr3)]

Abstract Two novel classes of very air-stable ruthenium carbene complexes have been developed. The arylthio substituted ruthenium carbenes containing two bulky phosphines are deep purple solids, whereas the 2-pyridylethanyl substituted ruthenium carbene complexes contain only one bulky phosphine and are light-brown colored. One member of each class has been characterized with X-ray crystallography. The metathesis activity of these complexes has been investigated in the polymerization of dicyclopentadiene. Several excellent catalysts were identified. Desired geltimes and initiation temperatures could be easily tuned by changing the substitution pattern on the pendant ligand in the 2-pyridylethanyl substituted ruthenium carbenes.

Ruthenium Catalysts for Ring-Opening Metathesis Polymerization (ROMP) and Related Chemistry

Ring-opening metathesis polymerization (ROMP), ring-closing metathesis (RCM) and ring-opening cross metathesis (RO/CM) are interesting methods to synthesize polymers with attractive mechanical and electrical properties, and specialty chemicals. Ruthenium and osmium based catalysts are water stable and possess a remarkable tolerance towards most functional groups. Whereas the first generation of well defined ruthenium based ROMP catalysts, cationic complexes like Ru(H2O)6tos2 (tos=toluene-4-sulfonate) and Ru(arene)2tos2 (activated by UV-irradiation) showed much lower reactivities as compared to “activated” early transition metal catalysts, Ru-phosphine complexes like RuCl2(p-MeC6H4CHMe2)(PCy3) (1, Cy=cyclohexyl) developed by Ciba SC and later Ru-phoshine-carbenes, developed by Grubbs et al. and Ciba SC are able to polymerize a large range of cycloolefins including DCPD (in technical quality and in mixtures with additives and fillers) very efficiently. The new classes of ruthenium carbene complexes are accessible by a novel synthesis which avoids the use of hydrogen gas and is therefore easy to scale up. Catalyst reactivities in ROMP of different monomers (characterized in terms of their turn-over frequencies (TOF) and compared with other catalysts for olefin polymerization), in RCM and RO/CM are very much dependent on the ligand sphere and the type of monomer used. Polymerizations were conducted in bulk, solution and dispersion with a large range of non-functionalized and functionalized 2-norbornene derivatives to obtain linear and crosslinked homo- and copolymers (block and random) which may find useful applications in the near future.

A 14-electron ruthenium hydride: the key intermediate in the synthesis of ruthenium carbene complexes; X-ray structure of [RuHCl(PPri3)2]

A simple one-pot procedure for the synthesis of ruthenium benzylidenes (Grubbs’ catalyst) has been developed in which a novel, highly reactive 14-electron ruthenium monohydride, prepared from [RuCl2(cod)] and two bulky phosphines in boiling propan-2-ol without the use of hydrogen gas, is reacted with hydrogen chloride, an alkyne and styrene.