Polymer depolymerization using ruthenium and osmium carbene complexes

摘要

Disclosed are ruthenium and osmium carbene compounds which are stable in the presence of a variety of functional groups and which can be used to catalyze olefin metathesis reactions on unstrained cyclic and acyclic olefins. Specifically, the present invention relates to carbene compounds of the formula ##STR1## wherein: M is Os or Ru; R and R.sup.1 are independently selected from hydrogen and functional groups C.sub.2 -C. sub. 20 alkenyl, C.sub.2 -C.sub.20 alkynyl, C.sub.1 -C.sub.20 alkyl, aryl, C. sub.1 -C.sub.20 carboxylate, C.sub.2 -C.sub.20 alkoxy, C.sub.2 -C.sub. 20 alkenyloxy, C.sub.2 -C.sub.20 alkynyloxy, aryloxy, C.sub.2 -C.sub.20 alkoxycarbonyl, C.sub.1 -C.sub.20 alkylthio, C.sub.1 -C.sub.20 alkylsulfonyl or C.sub.1 -C.sub.20 alkylsulfinyl; each optionally substituted with C.sub.1 -C.sub.5 alkyl, a halogen, C.sub.1 -C.sub.5 alkoxy or with a phenyl group optionally substituted with a halogen, C. sub.1 -C.sub.5 alkyl or C.sub.1 -C.sub.5 alkoxy; X and X.sup.1 are independently selected from any anionic ligand; and L and L.sup.1 are each trialkyl phosphine ligands where at least one of the alkyl groups on the phosphine is a secondary alkyl or a cycloalkyl. A broad array of metathesis reactions are enabled including ring-opening metathesis polymerization of cyclic olefins, ring closing metathesis of acyclic dienes, cross metathesis involving at least one acyclic or unstrained cyclic olefin, and depolymerization of unsaturated polymers.