The cyclopentadienyl ligand is an important ligand in organometallic chemistry because it will complex a wide range of transition metals.[1] Recently there has been an increased attention to cyclopentadiene ligands containing pendant groups that are capable of coordinating to a metal centre as well. Examples of these bidentate ligands are cyclopentadiene ligands containing amine[2,3], ether[4], amido[5,6] and alkoxy [7] pendant groups.
The asymmetric catalytic properties of cyclopentadiene metal complexes are also receiving more attention. Different strategies have been developed to introduce asymmetry in cyclopentadiene metal complexes.[8] Examples of these strategies are the use of cyclopentadiene ligands with a chiral substituent connected to the cyclopentadiene ring [9], the use of annulated chiral cyclopentadiene ligands [1,10] and the use of ansa-bridged bis-indenyl ligands in which the group bridging the two indenyls is either achiral [11] or chiral.[12] Chiral cyclopentadiene ligands containing a pendant donor have been described in only a few papers.[4,13] Recently the synthesis of a chiral cyclopentadiene ligand based on ephedrine and pseudo ephedrine was described.[14]