A metal complex comprising a metal compound complexed to a heteroatomic ligand, the metal complex having Structure X: ##STR00001## wherein R.sup.1, R.sup.2, R.sup.3, and R.sup.4 are each independently an alkyl group, a cycloalkyl group, a substituted cycloalkyl group, an aromatic group, or a substituted aromatic group, R.sup.1c, R.sup.2c, R.sup.3c, R.sup.4c, and R.sup.5c are each independently hydrogen or an alkyl group, and MX.sub.p comprises a group IVB, VB, or VIB metal. A metal complex comprising a metal compound complexed to a diphosphino aminyl ligand comprising at least two diphosphino aminyl moieties and a linking group linking each aminyl nitrogen atom of the diphosphino aminyl moieties.