Metallacyclopentadiene initiators for cyclic polymer synthesis from alkynes
View Patent ↗Provided herein are complexes for polymerization of linear alkynes to cyclic poly(alkynes), and methods of making and using same. For example, provided herein are compounds of formula (I) or formula (IV):
1. A compound having a structure represented by formula (I) or formula (IV):
wherein M is a transition metal;
each R 1 is independently H, C 1 -C 20 alkyl, carboxyl, ester, amino, thiol, halo, C 1 -C 22 haloalkyl, OH, or two adjacent R 1 , together with the carbon atoms to which they are attached, form a five- to eight-member cyclic group;
R 2 is selected from Ar 1 , C 1 -C 22 alkyl, halo, C 1 -C 22 haloalkyl, hydrogen, —NH 2 , —N—(C 1 -C 22 alkyl) 2 , —NH(C 1 -C 22 alkyl), —NHAr 1 , —NAr 1 2 , —O—Ar 1 , —O—(C 1 -C 22 alkyl), and (R 3 ) 3 —Si—;
each R 4 is independently C 1 -C 22 alkyl or both R 4 together with the carbon atom to which they are attached form a spiro five- to eight-member monocyclic group or a spiro eleven- to thirty-member polycyclic group;
each R 5 is independently H, C 1 -C 22 alkyl, —NH 2 , —N—(C 1 -C 22 alkyl) 2 , —NH(C 1 -C 22 alkyl), —NHAr 1 , —NAr 1 2 , —O—Ar 1 , —OH, or —O—(C 1 -C 22 alkyl);
each n is independently 1, 2, 3, 4, or 5;
each R 6 is independently H, C 1 -C 3 alkyl, halide, —NH 2 , —N—(C 1 -C 3 alkyl) 2 , —NH(C 1 -C 3 alkyl), —NHAr 1 , —NAr 1 2 , —O—Ar 1 , —O—(C 1 -C 3 alkyl), —S—Ar 1 , —S—(C 1 -C 3 alkyl);
each R 3 is independently selected from C 1 -C 22 alkyl, Ar 1 , —O—(C 1 -C 22 alkyl), —O—Ar 1 , —N(C 1 -C 22 alkyl) 2 , —NH(C 1 -C 22 alkyl), —NH 2 , or —NH—Ar 1 ;
A is selected from the group consisting of NH 3 , N(R 7 ) 3 , Ar 2 , C 1 -C 6 hydroxyalkyl, R 7 OR 7 , P(R 7 ) 3 , R 7 CHO, R 7 COR 7 , R 7 COOR 7 , and S(R 7 ) 2 ;
each Ar 1 and Ar 2 is independently an C 6 -C 22 aryl or 5-12 membered heteroaryl comprising from 1 to 3 heteroatoms selected from O, N, and S; and
each R 7 is independently C 1 -C 22 alkyl or Ar 2 , or two R 7 , together with the atoms to which they are attached, form a five- to eight-member heterocycle.
2. The compound of claim 1 , wherein M comprises a group 6 transition metal.
3. The compound of claim 1 , wherein the at least one R 1 comprises t-butyl.
4. The compound of claim 1 , wherein the at least two R 1 comprise t-butyl.
5. The compound of claim 4 , wherein the R 1 at the 6′ carbon and the R 1 at the 6″ carbon each comprises t-butyl.
6. The compound of claim 1 , wherein R 2 comprises t-butyl.
7. The compound of claim 1 , wherein both R 4 together with the carbon atom to which they are attached form a spiro five- to eight-member monocyclic group.
8. The compound of claim 1 , wherein both R 4 together with the carbon atom to which they are attached form a spiro eleven- to thirty-member polycyclic group.
9. The compound of claim 1 , wherein both R 4 together with the carbon atom to which they are attached form a fluorenyl group.
10. The compound of claim 1 , wherein each R 5 is hydrogen.
11. The compound of claim 1 , wherein both n are 1.
12. The compound of claim 1 , wherein each R 6 is hydrogen.
13. The compound of claim 1 , wherein A is THF.
14. The compound of claim 1 , selected from the group consisting of
15. A method for making the compound according to claim 1 , comprising reacting a complex of formula (II) and a dialkyne having a structure of formula (III) under conditions sufficient to form the compound according to claim 1 ;
wherein
each L is independently absent or selected from phosphine, phosphite, phosphonite, phosphinite, amine, amide, imine, alkoxy, ether, thioether, and a five- or six-membered monocyclic group having 1 to 3 ring heteroatoms;
or both L together comprise a bidentate ligand.
16. The method of claim 15 , wherein the complex of formula (II) has a structure represented by a formula:
17. The method of claim 15 , wherein at least one L is ether.
18. The method of claim 15 , wherein at least one L is a five- or six-membered monocyclic group having 1 to 3 ring heteroatoms.
19. A method of preparing a cyclic polymer, comprising:
admixing a plurality of alkynes in the presence of the compound of claim 1 under conditions sufficient to polymerize the plurality of alkynes, thereby forming the cyclic polymer from the plurality of alkynes, wherein the cyclic polymer ring comprises alkene groups.
20. The method of claim 19 , further comprising the step of hydrogenating the alkene groups.