The present disclosure relates to tungsten complexes, catalyst systems including tungsten complexes, and polymerization processes to produce polycycloolefin polymers such as polycyclopentene polymers and polycyclooctene polymers.

An improved catalyst for cyclic olefin polymerization. The catalyst includes a transition metal carbene having the following structure: M.sup.v(OR’).sub.c*mX(.sub.v-c*m-2)=C(R*).sub.2 wherein M.sup.v is a Group 5 transition metal having a valence (v) of 5 or a Group 6 transition metal having a valence (v) of 5 or 6; each R′ is independently a monovalent organic moiety comprising from 8 to 40 atoms selected from Groups 14-17; c is an integer from 1 to 3; m is ⅓, ½, 1, 3/2, 2, 3, or 4 and c*m ≤ v-2; X is a halogen; and each R* is independently H or a C.sub.1 to C.sub.7 alkyl. The catalyst is particularly useful for ring-opening metathesis polymerization (ROMP).

The present invention relates to a catalyst system containing a metathesis catalyst containing at least one N-heterocyclic carbene ligand and at least one phenolic compound and to a process for performing the metathesis on nitrile rubbers for reducing their molecular weight using a metathesis catalyst containing at least one N-heterocyclic carbene ligand (NHC ligand) and at least one phenolic compound.

The present invention relates to a stabilized rhenium-based heterogeneous catalyst, obtainable by a process comprising contacting a rhenium-based heterogeneous catalyst with a stabilizing agent at a temperature in a range from 0-100° C., the stabilizing agent comprising an aliphatic hydrocarbon compound and use thereof.

The present invention relates to a catalyst system containing a metathesis catalyst containing at least one N-heterocyclic carbene ligand and at least one phenolic compound and to a process for performing the metathesis on nitrile rubbers for reducing their molecular weight using a metathesis catalyst containing at least one N-heterocyclic carbene ligand (NHC ligand) and at least one phenolic compound.

A new family of mononuclear organometallic complexes of a divalent metal bound to sequential tetradentate monoanionic {ONNN}-type ligands, and polymerization of cyclic esters such as lactides utilizing same are provided. Novel tetradentate monoanionic {ONNN}-type ligands usable for forming these complexes are also provided.

The invention relates to tungsten imido alkylidene compounds bearing a ligand derived from a 1,1′-binaphthyl-2-ol or a 5,5′,6,6′,7,7′,8,8′-octahydro-1,1′-binaphthyl-2-ol which bind to tungsten in its olate-form via proton abstraction from the phenolic OH group. The complexes may be used in various olefinic metathesis reactions, preferably ethenolysis and cross-metathesis of unsaturated fatty acid esters, and ring-closing metathesis reactions.

The invention provides a new process for producing ruthenium complexes represented by the Formula 1. Invention provides also the use of ruthenium complexes represented by the Formula 1 as precatalysts and/or catalysts in olefin metathesis reactions.

Use of compounds selected from copper complexes having at least one organic ligand and ruthenium complexes having at least one organic ligand, for activating olefin metathesis ruthenium (pre)catalysts in a metathesis reaction, in particular in the ring opening metathesis polymerization reaction (ROMP).

Nitrogen heterocyclic carbine ligands and ruthenium catalysts thereof, a preparation method therefor and an application thereof are provided. The structures of the nitrogen heterocyclic carbine ligands are represented by formulas Ia and Ib, respectively, and the corresponding ruthenium catalyst structures are represented by IIa and IIb, respectively. After simultaneously introducing large-steric hindrance and electron-rich groups into the described nitrogen heterocyclic carbine ligand structures, the catalytic activity, stability and application range of the ruthenium complex catalysts thereof are significantly improved.

##STR00001##