A metallocene complex of formula (I): each X is a sigma-ligand; in the group R 2 Si- at least one R is methyl or ethyl, and the other R is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl or isobutyl, pentyl, hexyl, cyclohexyl and phenyl; each R 1 independently is the same or can be different and are a CH 2 -R 7 group, with R 7 being H or linear or branched C 1-6 -alkyl group, C 3-8 cycloalkyl group, or C 6-10 aryl group; each R 2 is independently a -CH=, -CY=, -CH 2 -, -CHY- or -CY 2 - group, wherein Y is a C 1-6 hydrocarbyl group and where n is 2-6; each R 3 and R 4 are independently the same or can be different and are hydrogen, a linear or branched C 1-6 -alkyl group, a C 7-20 arylalkyl, C 7-20 alkylaryl group, C 6-20 aryl group, or an -OY group, wherein Y is a is a C 1-6 hydrocarbyl group; R 5 is a linear or branched C 1-6 -alkyl group, C 7-20 arylalkyl, C 7-20 alkylaryl group or C 6-20 -aryl group; and R 6 is a C(R 8 ) 3 group, with each R 8 being independently a linear or branched C 1-6 alkyl group; (A) wherein at least one R 3 per phenyl group and at least one R 4 is not hydrogen, and wherein at least one R 3 per phenyl group and at least one R 4 is hydrogen; or (B) wherein one R 3 is an -OY group, wherein Y is a is a C 1-6 hydrocarbyl group, in 4 position of each phenyl group and the two other R 3 groups are tert-butyl groups; and/or (C) wherein one R 4 is an -OY group, wherein Y is a is a C 1-6 hydrocarbyl group, in 4- position of the phenyl ring and the two other R 4 groups are tert-butyl groups. each X is a sigma-ligand; in the group R 2 Si- at least one R is methyl or ethyl, and the other R is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl or isobutyl, pentyl, hexyl, cyclohexyl and phenyl; each R 1 independently is the same or can be different and are a CH 2 -R 7 group, with R 7 being H or linear or branched C 1-6 -alkyl group, C 3-8 cycloalkyl group, or C 6-10 aryl group; each R 2 is independently a -CH=, -CY=, -CH 2 -, -CHY- or -CY 2 - group, wherein Y is a C 1-6 hydrocarbyl group and where n is 2-6; each R 3 and R 4 are independently the same or can be different and are hydrogen, a linear or branched C 1-6 -alkyl group, a C 7-20 arylalkyl, C 7-20 alkylaryl group, C 6-20 aryl group, or an -OY group, wherein Y is a is a C 1-6 hydrocarbyl group; R 5 is a linear or branched C 1-6 -alkyl group, C 7-20 arylalkyl, C 7-20 alkylaryl group or C 6-20 -aryl group; and R 6 is a C(R 8 ) 3 group, with each R 8 being independently a linear or branched C 1-6 alkyl group; (A) wherein at least one R 3 per phenyl group and at least one R 4 is not hydrogen, and wherein at least one R 3 per phenyl group and at least one R 4 is hydrogen; or (B) wherein one R 3 is an -OY group, wherein Y is a is a C 1-6 hydrocarbyl group, in 4 position of each phenyl group and the two other R 3 groups are tert-butyl groups; and/or (C) wherein one R 4 is an -OY group, wherein Y is a is a C 1-6 hydrocarbyl group, in 4- position of the phenyl ring and the two other R 4 groups are tert-butyl groups. (A) wherein at least one R 3 per phenyl group and at least one R 4 is not hydrogen, and wherein at least one R 3 per phenyl group and at least one R 4 is hydrogen; or (B) wherein one R 3 is an -OY group, wherein Y is a is a C 1-6 hydrocarbyl group, in 4 position of each phenyl group and the two other R 3 groups are tert-butyl groups; and/or (C) wherein one R 4 is an -OY group, wherein Y is a is a C 1-6 hydrocarbyl group, in 4- position of the phenyl ring and the two other R 4 groups are tert-butyl groups. <EOS>