A facile and high yielding synthesis for two new families of scorpionate/cyclopentadienyl hybrid monoalkyl κ2-NN-η5-C5H4 magnesium and κ2-NN-η1(π)-C5H4 zinc complexes [M(R)(bpzcp)] is described. Furthermore, the preparations of chloride, alkoxide and aromatic/aliphatic amides compounds are also presented. Finally, alkyl and alkoxide-containing magnesium and zinc complexes can act as highly effective single-component living initiators for the well-controlled ring-opening polymerization of cyclic esters over a wide range of temperatures.