Fig. 2.

Synthesis of complexes 2ThBIPY and 2ThNHRK. The known dialkyl complex 3 can be reacted two equivalents of trityl-amine by protonolysis to give the diamide complex 4. Complex 4 when treated with two equivalent of benzyl potassium (to maximise the yield, a stoichiometric amount of benzyl potassium gives lower yields) converts to the amide-imide complex 2ThNHRK. Complex 3 can alternatively be reacted with a sub-stoichiometric quantity of trityl-amine (to suppress ligand-redistribution reactions) to give, via protonolysis, the mixed alkyl-amide complex 5. Complex 5 undergoes α-hydrogen abstraction on addition of BIPY to give 2ThBIPY