where

M is hafnium or zirconium;

each R¹ is methyl;

each R² is independently selected from the group consisting of methyl, ethyl, propyl, butyl, pentyl, hexyl and the isomers thereof, provided that when R³ and R⁶ and or R¹² and R¹⁵ form a 5 carbon ring, then each R² is independently selected from the group consisting of ethyl, propyl, butyl, pentyl, hexyl and the isomers thereof;

R³ is carbon;

R⁴ is CH₂;

a is 1;

R⁵ is CH₂;

b is 1;

R⁶ is carbon; and R³, R⁴, R⁵ and R⁶ are bound together to form a ring;

each R⁷ is hydrogen;

each R⁸ is hydrogen;

each R⁹ is independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl and a functional group, and two R⁹ groups may be linked together to form a ring, R⁹ and R⁸ may be linked together to form a ring, R⁹ and R¹⁶ may be linked together to form a ring, R⁹ and R¹¹ may be linked together to form a ring;

c is 0;

R¹⁰ is -M²(R¹⁶)_h— where M² is Si, h is an integer from 1 to 2, such that the valence of M² is filled, and R¹⁶ is hydrogen, hydrocarbyl, substituted hydrocarbyl or a functional group, and two R¹⁶ groups may be linked together to form a ring;

d is 1;

each R¹¹ is independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl and a functional group, and two R¹¹ groups may be linked together to form a ring R¹¹ and R⁸ may be linked together to form a ring R¹¹ and R¹⁶ may be linked together to form a ring;

e is 1;

where the sum of c, d, and e is 2;

R¹² is carbon;

R¹³ is CH₂;

f is 1;

R¹⁴ is CH₂;

g is 1; and

R¹⁵ is carbon.