Long-lived homogenous oxidation catalysts

A compound comprising:

• a macrocyclic tetradentate ligand of the structure ##STR40## wherein R.sub.1 and R.sub.2 are the same or different, linked or nonlinked, and each is selected from the group consisting of substituents which are unreactive, form strong bonds intramolecularly within said R.sub.1 and R.sub.2 and with the cyclic carbon C.sub.1, are sterically hindered and are conformationally hindered such that oxidative degradation of a metal complex of the compound is restricted when the complex is in the presence of an oxidizing medium;
• Z is a metal complexing atom N;
• X is O or NR, wherein R is alkyl, aryl, halogenated alkyl, halogenated aryl, methyl, hydroxy, oxylic, CF.sub.3, CH.sub.2 CF.sub.3 ;
• wherein both Z and X are resistant to oxidative degradation such that each confers resistance to oxidative degradation to the metal complex of the compound when the complex is in the presence of an oxidizing medium;
• R.sub.3 is a unit joining the adjacent Z atoms comprised of ##STR41## wherein R.sub.6, R.sub.7, R.sub.8 and R.sub.9 pairwise and cumulatively are the same or different and each is selected from the group consisting of alkyl, aryl, halogen halogenated alkyls, halogenated aryls, and CF.sub.3 ;
• and
• R.sub.4 is a unit joining the adjacent Z atoms comprised of ##STR42## wherein R.sub.10, R.sub.11, R.sub.12 and R.sub.13 pairwise and cumulatively are the same or different and each is selected from the group consisting of alkyl, aryl, halogen halogenated alkyls, halogenated aryls and CF.sub.3 ;
• R.sub.5 is a unit joining adjacent Z atoms selected from the group consisting of (i) ##STR43## wherein R.sub.14, R.sub.15, R.sub.16 and R.sub.17 are the same or different and each is alkyl, aryl, halogen and CF.sub.3, and (ii) mono-, di-, tri- and tetra-substituted aryl and heteroaryl substituents.