Patent ID: 8492493

Claim:
A pro-ligand of formula I or its tautomeric form of formula I′ wherein R 1 , R 3 , R 4 , R 5 , R 6 and R 7 are each independently selected from hydrogen, unsubstituted or substituted hydrocarbyl, or inert functional group, wherein two or more of said groups can be linked together to form one or more rings, Z is an atom selected from group 14 of the Periodic Table, each R 2 is independently selected from a substituted or unsubstituted aryl group having at most 8 carbon atoms, and/or an alkyl group, with the restriction that Z(R 2 ) 3 is a bulky group, at least as bulky as tertio-butyl, R 8 is CH 2 -(2-pyridyl), alpha-quinolone or C 6 F 5 , possibly containing donor atoms.