Catalysts containing per-ortho aryl substituted aryl or heteroaryl substituted nitrogen donors

A compound selected from Set 21;

• wherein:
• R2x,y are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl;
• in addition, R2x and R2y may be linked by a bridging group;
• R3a-f are each independently H, alkyl, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, or fluoroalkyl;
• and
• Ar1a-d are each independently phenyl, 4-alkylphenyl, 4-tert-butylphenyl, 4-trifluoromethylphenyl, 4-hydroxyphenyl, 4-(heteroatom attached hydrocarbyl)-phenyl, 4-(heteroatom attached substituted hydrocarbyl)-phenyl, 1-naphthyl, 2-naphthyl, 9-anthracenyl, or aryl.