The present invention provides stable, cyclic bent allene metal complexes and methods of conducting chemical processes, preferably olefin hydrogenation, comprising contacting an olefin substrate, preferably an unsaturated polymer, with a cyclic bent allene metal complex as described herein, under hydrogenation conditions. wherein M is a transition metal selected from Groups 6-11 of the periodic table, L 1 is a cyclic bent allene ligand according to the general formula (II)