The cyclopentadienyl-type ligands of the present invention are represented by the formula ZA, wherein Z is a cyclopentadienyl-type group and A is --YPR2, --YNR2, or --NR2, wherein Y is an alkylene group containing 1 to 24 carbon atoms, wherein each R is individually selected from alkyl groups containing 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms, and