The present invention provides a metallocenyl compound of formula (I). R a , R b , R c , R d , R e , R f , M, m, n, j, k, Y and Z and * are as described in the specification. The invention also provides a process for the preparation of the complexes, a process for increasing the optical purity of a compound of formula (II) and a process for the asymmetric transfer hydrogenation (ATH) of a metallocenyl compound of formula (V) to a metallocenyl compound of formula (IV).