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

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.