Olefin metathesis for metal incorporation: Preparation of conjugated ruthenium-containing complexes and polymers

Olefin Metathesis for Metal Incorporation (OMMI) was used for the stoichiometric attachment of ruthenium to both small and large polyenes. The dinuclear complexes (PCy₃)₂C1₂Ru{double bond, long}CH(CH{double bond, long}CH)_nCH{double bond, long}Ru(PCy₃)₂Cl₂ (n = 1, 2), were prepared by reacting 2 equiv. of the Grubbs first-generation catalyst (PCy₃)₂C1₂Ru{double bond, long}(CHPh)) with 1 equiv. of the appropriate polyene (1,3,5-hexatriene for n = 1 and 1,3,5,7-octatetraene for n = 2). Use of excess hexatriene led to the formation of the monoruthenium complex (PCy₃)₂C1₂Ru{double bond, long}CHCH{double bond, long} CHCH{double bond, long}CH₂. The mono- and di-ruthenium complexes exhibited marked differences in their spectroscopic and electrochemical properties, in addition to their Z-E isomerization rates. Nucleophilic attack of PCy₃ on the end CH₂ of the mono complex was observed, leading to both isomerization and phosphonium products. Extending the OMMI strategy to the second-generation catalyst was also done, despite the reduced initiation rate. The more reactive catalyst (H₂IMes)RuCl₂({double bond, long}CHPh)(3-bromopyridine)₂ allowed for ruthenium incorporation into polyacetylene, leading to the formation of polymers and oligomers with high ruthenium content.