Cyclic ruthenium benzylidene initiators for enhanced ring expansion metathesis polymerization

A compound of Formula (I):

• wherein:
• X1 and X2 are each independently halo;
• Lig1 is an unsaturated N-heterocyclic carbene comprising 1, 2, 3, or 4 N atoms, wherein said unsaturated N-heterocyclic carbene is optionally substituted with 1, 2, or 3 substituents each independently selected from halo, aryl, heteroaryl, C1-6 alkyl, and C1-6 haloalkyl, wherein said aryl, heteroaryl, C1-6 alkyl, and C1-6 haloalkyl are further each optionally substituted with 1, 2, 3, or 4 substituents each independently selected from halo, C1-6 alkyl, and C1-6 haloalkyl;
• or
• Lig1 is a moiety of Formula (A-1):
• wherein:
• R3 is selected from aryl and heteroaryl, each optionally substituted with 1, 2, 3, or 4 substituents each independently selected from halo, C1-6 alkyl, and C1-6 haloalkyl;
• and
• R4 and R5 are each independently selected from H, C1-3 alkyl, halo, C1-3 haloalkyl, aryl, and heteroaryl;
• Lig2 is selected from a phosphine and heteroaryl, each optionally substituted with 1, 2, 3, or 4 substituents each independently selected from halo, C1-6 alkyl, C1-6 haloalkyl, cycloalkyl, and aryl;
• Lig3 is selected from absent and heteroaryl, wherein the heteroaryl is optionally substituted with 1, 2, 3, or 4 substituents each independently selected from halo, C1-6 alkyl, C1-6 haloalkyl, cycloalkyl, and aryl;
• R1 is selected from C1-12 alkylene, arylene, and heteroarylene, each optionally substituted with 1, 2, 3, or 4 substituents each independently selected from halo, C1-6 alkyl, and C1-6 haloalkyl;
• R2 is selected from arylene and heteroarylene, each optionally substituted with 1, 2, 3, or 4 substituents each independently selected from halo, C1-6 alkyl, and C1-6 haloalkyl;
• W1 and W2 are each independently selected from O, C(R6′)(R7′), S, and N (R6″), wherein R6′, R7′, and R6″ are each independently selected from H, halo, C1-6 alkyl, and C1-6 haloalkyl;
• L1, at each occurrence, is selected from C(R6)(R7), arylene, and heteroarylene, wherein said R6 and R7 are each independently selected from H, halo, C1-3 alkyl, aryl, and heteroaryl;
• and
• wherein said arylene and heteroarylene are each optionally substituted with 1, 2, 3, or 4 substituents each independently selected from halo, C1-6 alkyl, and C1-6 haloalkyl;
• and
• n is an integer selected from 3 to 24.