ligand as used herein means an ion molecule and or functional group that binds to a metal atom to form a coordination complex the bonding between the metal and the ligand generally involves formal donation of one or more of the ligand 39 s electron pairs the metal ligand bonding can range from covalent to ionic suitable ligands for the catalysts described herein include i ligands formed by deprotonation of a u03b2 diketone a u03b2 ketoester a u03b2 ketoamide or a combination thereof ii halide counteranion ligands each derived from chloride fluoride bromide iodide a compound resulting from the partial alcoholysis or hydrolysis of any of these iron halide compounds or a combination thereof iii u03b1 diimine ligands each derived from 2 2 u2032 bipyridine 1 10 phenanthroline substituted variants of 2 2 u2032 bipyridine or 1 10 phenanthroline or some combination thereof or iv any combination thereof in some embodiments the ligands are not mixed all ligands in the catalyst are the same in some embodiments the ligands of the catalyst are derived from 2 4 pentanedionate 1 1 1 trifluoro 2 4 pentanedionate 1 1 1 5 5 5 hexafluoro 2 4 pentanedionate 2 2 6 6 tetramethyl 3 5 heptanedionate 6 methyl 2 4 heptanedionate chloride 2 2 u2032 bipyridine chloride or combinations thereof the catalyst may include a compound having the general structure x m m y n where m is 2 or 3 m is iron each x is independently a ligand with a u2212 1 charge each y is a neutral ligand and n is an integer between 0 and 6 the ligands of.