Synthesis and Catalytic Activity of Ruthenium–Indenylidene Complexes for Olefin Metathesis

Abstract

A series of experiments for undergraduate laboratory courses (e.g., inorganic, organometallic or advanced organic) have been developed. These experiments focus on understanding the design and catalytic activity of ruthenium–indenylidene complexes for olefin metathesis. Included in the experiments are the syntheses of two ruthenium–indenylidene complexes that can be conveniently prepared from commercially available starting materials. The two complexes differ only by the nature of the phosphine ligand, yet each complex displays drastically different catalytic activity in a ring-closing metathesis (RCM) reaction. When the triphenylphosphine-containing complex is utilized, little or no catalytic activity is observed. Substitution of the complex with tricyclohexylphosphine, however, results in a complex with excellent catalytic activity in a RCM reaction. These experiments demonstrate the importance of catalyst design and expose students to the important field of olefin metathesis. Students also utilize several analytical methods (1H and 31P NMR, GC–MS, FT-IR) in characterizing the complexes and quantifying catalytic activity.

Ruthenium-Based Olefin Metathesis Catalysts Derived from Alkynes

“…In recent years, the development and application of ruthenium indenylidene type catalysts 133 has received widespread attention due to their high activity in various olefin metathesis reactions and their comparable ease of synthesis. 134 We have previously stressed the importance of straightforward synthetic routes to ruthenium alkylidene complexes, and ruthenium indenylidene complexes, readily prepared upon reaction of propargylic alcohol and Cl 2 Ru(PPh 3 ) 3-4 , are interesting candidates in this respect. Moreover, most of the reported ruthenium indenylidene complexes exhibit high air and moisture stability, good thermal stability, and excellent tolerance toward functional groups.…”

Polymer Chemistry in an Undergraduate Curriculum

“…Ring opening metathesis polymerization (ROMP) exploits the metathesis equilibrium by using the relief of ring strain to drive the formation of, often trans, double bonds (Scheme 11). Typical monomers are cyclooctene, cyclooctadiene, norbornene, and norbornadiene derivatives (40)(41)(42)(43)(44)(45)(46). Monomers with functional groups, e.g.…”

Learning Green Chemistry Principles by Comparing Three Synthetic Routes to a Copper-NHC (NHC = N-heterocyclic carbene) Complex

“…Recent work in chemical education has shown that students display great interest and enthusiasm in learning sustainable methods and laboratory exercises showing how chemists can implement changes in future chemical processes. Multiple laboratory exercises address the aspects of transition-metal catalysis − and mechanochemistry − for undergraduate students, but combining both techniques and showing students how chemical processes are adapted over time to achieve increased sustainability has been, to the best of our knowledge, overlooked. The recent development of a new synthetic methodology for [Cu­(Cl)­(NHC)] complexes provides an excellent opportunity to create a new laboratory experiment for undergraduate students in which green chemistry, mechanochemistry, and catalysis aspects are introduced simultaneously.…”