A dinuclear metallocene compound having the formula: or wherein: each X 1, X 2, X 5, X 6, X 9, and X 10 independently is hydrogen; BH 4; a halide; a hydrocarbyl group, hydrocarbyloxide group, hydrocarbyloxylate group, hydrocarbylamino group, or hydrocarbylsilyl group, any of which having up to 20 carbon atoms; or OBR A 2 or SO 3 R A, wherein R A is an alkyl group or aryl group having up to 12 carbon atoms; each X 3 independently is a substituted or unsubstituted cyclopentadienyl, indenyl, or fluorenyl group, any substituents on X 3 independently are a hydrogen atom or a substituted or unsubstituted alkyl or alkenyl group; each X 4 independently is a substituted cyclopentadienyl, indenyl, or fluorenyl group, any substituents on X 4 other than an alkenyl linking group independently are a hydrogen atom or a substituted or unsubstituted alkyl or alkenyl group; each X 7, X 11, and X 12 independently is a substituted cyclopentadienyl, indenyl, or fluorenyl group, any substituents on X 7, X 11, and X 12 other than a bridging group independently are a hydrogen atom or a substituted or unsubstituted alkyl or alkenyl group; each X 8 is a substituted cyclopentadienyl, indenyl, or fluorenyl group, any substituents on X 8 other than a bridging group and an alkenyl linking group independently are a hydrogen atom or a substituted or unsubstituted alkyl or alkenyl group; each A 1 independently is a substituted or unsubstituted bridging group comprising either a cyclic group of 5 to 8 carbon atoms, a bridging chain of 2 to 5 carbon atoms, or a carbon, silicon, germanium, tin, boron, nitrogen, or phosphorus bridging atom, any substituents on A 1 independently are a hydrogen atom, or a substituted or unsubstituted aliphatic, aromatic, or cyclic group, or a combination thereof; each A 2 independently is a substituted bridging group comprising either a silicon bridging atom, a germanium bridging atom, a tin bridging atom, a carbon bridging atom, or a bridging chain of 2 to 5 carbon atoms, any substituents on A 2 other than the alkenyl linking group independently are a hydrogen atom, or a substituted or unsubstituted aliphatic, aromatic, or cyclic group, or a combination thereof; each M 1, M 2, and M 3 independently is Zr, Hf, or Ti; each E independently is carbon or silicon; each R X, R Y, and R Z independently is a hydrogen atom, or a substituted or unsubstituted aliphatic, aromatic, or cyclic group, or a combination thereof; and each n independently is an integer in a range from 0 to 12, inclusive. each X 1, X 2, X 5, X 6, X 9, and X 10 independently is hydrogen; BH 4; a halide; a hydrocarbyl group, hydrocarbyloxide group, hydrocarbyloxylate group, hydrocarbylamino group, or hydrocarbylsilyl group, any of which having up to 20 carbon atoms; or OBR A 2 or SO 3 R A, wherein R A is an alkyl group or aryl group having up to 12 carbon atoms; each X 3 independently is a substituted or unsubstituted cyclopentadienyl, indenyl, or fluorenyl group, any substituents on X 3 independently are a hydrogen atom or a substituted or unsubstituted alkyl or alkenyl group; each X 4 independently is a substituted cyclopentadienyl, indenyl, or fluorenyl group, any substituents on X 4 other than an alkenyl linking group independently are a hydrogen atom or a substituted or unsubstituted alkyl or alkenyl group; each X 7, X 11, and X 12 independently is a substituted cyclopentadienyl, indenyl, or fluorenyl group, any substituents on X 7, X 11, and X 12 other than a bridging group independently are a hydrogen atom or a substituted or unsubstituted alkyl or alkenyl group; each X 8 is a substituted cyclopentadienyl, indenyl, or fluorenyl group, any substituents on X 8 other than a bridging group and an alkenyl linking group independently are a hydrogen atom or a substituted or unsubstituted alkyl or alkenyl group; each A 1 independently is a substituted or unsubstituted bridging group comprising either a cyclic group of 5 to 8 carbon atoms, a bridging chain of 2 to 5 carbon atoms, or a carbon, silicon, germanium, tin, boron, nitrogen, or phosphorus bridging atom, any substituents on A 1 independently are a hydrogen atom, or a substituted or unsubstituted aliphatic, aromatic, or cyclic group, or a combination thereof; each A 2 independently is a substituted bridging group comprising either a silicon bridging atom, a germanium bridging atom, a tin bridging atom, a carbon bridging atom, or a bridging chain of 2 to 5 carbon atoms, any substituents on A 2 other than the alkenyl linking group independently are a hydrogen atom, or a substituted or unsubstituted aliphatic, aromatic, or cyclic group, or a combination thereof; each M 1, M 2, and M 3 independently is Zr, Hf, or Ti; each E independently is carbon or silicon; each R X, R Y, and R Z independently is a hydrogen atom, or a substituted or unsubstituted aliphatic, aromatic, or cyclic group, or a combination thereof; and each n independently is an integer in a range from 0 to 12, inclusive.