Polymerization catalysts to produce polymers with low levels of long chain ramification.

Acatalyst composition comprising the contact product of at least one ansa-metallocene, at least one organoaluminum compound, and at least one activator-support, wherein: a) ansa-metallocene comprises a compound having the formula: (X1) (X2) (X3) (X4) M1, wherein M1 is titanium, zirconium, or hafnium; (X1) and (X2) are independently a cyclopentadienyl, an indenyl, a fluorenyl or a substituted analog thereof, wherein at least one of (X1) and (X2) is substituted; at least one substituted substitute (X1) or (X2) comprises an unsaturated group having the formula -SiR42R5, wherein each R4 is independently a hydrocarbyl group or substituted hydrocarbyl group having from 1 to 20 carbon atoms; R5 is an alkenyl group, an alkynyl group, an alkadienyl group, or a substituted analog thereof having from 2 to 20 carbon atoms; (X1) and (X2) are connected by a group that bridges a substituted or unsubstituted bridge comprising an atom linked to (X1) and (X2), where the atom is carbon, silicon, germanium, or tin; and any substitute in R4, any substitute in R5, any substitute in the group that bridges over substituted, any additional substitute on (X1) or (X2), and (X3) and (X4) are independently an aliphatic group, a aromatic group, a cyclic group, a combination of aliphatic and cyclic groups; an oxygen group, a sulfide group, a nitrogen group, a phosphorus group, an arsenic group, a carbon group, a silicon group, a germanium group, a tin group, a lead group, a boron group, an aluminum group, a inorganic group, an organometallic group, or a substituted derivative thereof, any of which having from 1 to 20 carbon atoms; a halide; or hydrogen; b) the organoaluminum compound comprises a compound with the formula: Al (X5) n (X6) 3-n, wherein (X5) is a hydrocarbyl having from 1 to 20 carbon atoms; (X6) is an alkoxide or an aryloxide having from 1 to 20 carbon atoms, the halide, or hydride; and n is a number from 1 to 3, inclusive; and c) activator-support comprises: a solid oxide treated with an electro-acceptor anion; a layered mineral, an ion-exchangeable activator-support, or any combination of these.