Latent, high-activity olefin metathesis catalysts containing an N-heterocyclic carbene ligand
The invention provides novel organometallic complexes useful as olefin metathesis catalysts. The complexes have an N-heterocyclic carbene ligand and a chelating carbene ligand associated with a Group 8 transition metal center. The molecular structure of the complexes can be altered so as to provide a substantial latency period. The complexes are particularly useful in catalyzing ring closing metathesis of acyclic olefins and ring opening metathesis polymerization of cyclic olefins.
1. A complex having the structure of formula (I)
wherein:
α and β represent single bonds or unsaturated bonds, with the proviso that α and β cannot both be unsaturated bonds;
M is a Group 8 transition metal;
R 1 and R 2 are independently selected from hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, substituted heteroatom-containing hydrocarbyl, and functional groups;
Q is an organic diradical;
X 1 and X 2 are cis anionic ligands, and may be the same or different;
L 1 is a neutral electron donor ligand, and p is zero or 1;
when α is a single bond, L 2 is selected from NR 7 R 8 , PR 7 R 8 , N═CR 7 R 8 , and R 7 C═NR 8 , where R 7 and R 8 are independently selected from substituted and/or heteroatom-containing C 1 -C 20 alkyl, C 2 -C 20 alkenyl, C 2 -C 20 alkynyl, and C 5 -C 24 aryl, or R 7 and R 8 can be taken together to form a heterocyclic ring;
when α is an unsaturated bond, L 2 is selected from NR 7 and PR 7 , where R 7 is as defined previously, or L 2 and Z represent adjacent atoms in an aromatic ring;
Y and Z are linkages independently selected from hydrocarbylene, substituted hydrocarbylene, heteroatom-containing hydrocarbylene, substituted heteroatom-containing hydrocarbylene, —O—, —S—, —NR 9 , and —PR 9 —, wherein R 9 is selected from hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl, and further wherein Y and Z may represent adjacent atoms in an aromatic ring;
m is zero or 1;
n is zero or 1; and
wherein the complex is a positional isomer, wherein L 2 and the ligand containing Q are bonded to M in a cis orientation.
2. A complex of claim 1 having the structure of formula (II)
wherein:
β represents a single bond or an unsaturated bond;
M is a Group 8 transition metal;
R 1 and R 2 are independently selected from hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, substituted heteroatom-containing hydrocarbyl, and functional groups;
Q is an organic diradical;
X 1 and X 2 are cis anionic ligands, and may be the same or different;
L 1 is a neutral electron donor ligand, and p is zero or 1;
R 7 and R 8 are independently selected from substituted and/or heteroatom-containing C 1 -C 20 alkyl, C 2 -C 20 alkenyl, C 2 -C 20 alkynyl, and C 5 -C 24 aryl, or R 7 and R 8 can be taken together to form a heterocyclic ring;
Y and Z are linkages independently selected from hydrocarbylene, substituted hydrocarbylene, heteroatom-containing hydrocarbylene, substituted heteroatom-containing hydrocarbylene, —O—, —S—, —NR 9 , and —PR 9 —, wherein R 9 is selected from hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl, and further wherein Y and Z may represent adjacent atoms in an aromatic ring; and
wherein the complex is a positional isomer, wherein NR 7 R 8 and the ligand containing Q are bonded to M in a cis orientation.
3. The complex of claim 2 , wherein R 7 and R 8 are C 1 -C 12 alkyl or C 5 -C 12 aryl, and Y is a substituted or unsubstituted methylene or ethylene linkage.
4. A complex of claim 1 having the structure of formula (III)
wherein:
β represents a single bond or an unsaturated bond;
M is a Group 8 transition metal;
R 1 and R 2 are independently selected from hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, substituted heteroatom-containing hydrocarbyl, and functional groups;
Q is an organic diradical;
X 1 and X 2 are cis anionic ligands, and may be the same or different;
L 1 is a neutral electron donor ligand, and p is zero or 1;
R 7 and R 8 are independently selected from substituted and/or heteroatom-containing C 1 -C 20 alkyl, C 2 -C 20 alkenyl, C 2 -C 20 alkynyl, and C 5 -C 24 aryl, or R 7 and R 8 can be taken together to form a heterocyclic ring;
Y and Z are linkages independently selected from hydrocarbylene, substituted hydrocarbylene, heteroatom-containing hydrocarbylene, substituted heteroatom-containing hydrocarbylene, —O—, —S—, —NR 9 , and —PR 9 —, wherein R 9 is selected from hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl, and further wherein Y and Z may represent adjacent atoms in an aromatic ring; and
wherein the complex is a positional isomer, wherein PR 7 R 8 and the ligand containing Q are bonded to M in a cis orientation.
5. The complex of claim 4 , wherein R 7 and R 8 are C 1 -C 12 alkyl or C 5 -C 12 aryl, and Y is a substituted or unsubstituted methylene or ethylene linkage.
6. The complex of claim 5 , wherein R 7 and R 8 are phenyl and Y is ethylene.
7. A complex of claim 1 having the structure of formula (IV)
wherein:
M is a Group 8 transition metal;
R 1 and R 2 are independently selected from hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, substituted heteroatom-containing hydrocarbyl, and functional groups;
Q is an organic diradical;
X 1 and X 2 are cis anionic ligands, and may be the same or different;
L 1 is a neutral electron donor ligand, and p is zero or 1;
Y is a linkage selected from hydrocarbylene, substituted hydrocarbylene, heteroatom-containing hydrocarbylene, substituted heteroatom-containing hydrocarbylene, —O—, —S—, —NR 9 , and —PR 9 —, wherein R 9 is selected from hydrocarbyl, substituted hydrocarhyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl; and wherein the complex is a positional isomer having a pyridine ligand, wherein the pyridine ligand and the ligand containing Q are bonded to M in a cis orientation.
8. A complex of claim 1 having the structure of formula (V)
wherein:
M is a Group 8 transition metal;
R 1 and R 2 are independently selected from hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, substituted heteroatom-containing hydrocarbyl, and functional groups;
Q is an organic diradical;
X 1 and X 2 are cis anionic ligands, and may be the same or different;
L 1 is a neutral electron donor ligand, and p is zero or 1; and
R 7 is selected front substituted and/or heteroatom-containing C 1 -C 20 alkyl, C 2 -C 20 alkenyl,C 2 -C 20 alkynyl, and C 5 -C 24 aryl;
Y and Z are linkages independently selected from hydrocarbylene, substituted hydrocarbylene, heteroatom-containing hydrocarbylene, substituted heteroatom-containing hydrocarbylene, —O—, —S—, —NR 9 , and —PR 9 —, wherein R 9 is selected from hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl; and
wherein the complex is a positional isomer, wherein NR 7 and the ligand containing Q are bonded to M in a cis orientation.
9. A method for catalyzing an olefin metathesis reaction, comprising contacting an olefinic reactant with the complex of claim 1 under reaction conditions selected to enable olefin metathesis.
10. The complex of claim 1 , wherein the complex has the structure
11. A method for controlling the reaction latency period of an olefin metathesis reaction, comprising combining an olefin metathesis reaction mixture with a complex of claim 1 under reaction conditions selected to enable olefin metathesis.
12. The method of claim 11 , wherein the organometallic complex exhibits a latency period when combined with the olefin metathesis reaction mixture.
13. The method of claim 12 , wherein the latency period is at least two minutes.