Ruthenium Complexes of κ(P)- and κ(P)-η6-Coordinated KITPHOS Monophosphines: Efficient Catalysts for the Direct Ortho Arylation of 2-Phenylpyridine and N-Phenylpyrazole with Aryl Chlorides

Thermolysis of the P-coordinated KITPHOS monophosphine complex [(p-cymene)RuCl2(KITPHOS)] in chlorobenzene at 120 degrees C resulted in displacement of the p-cymene to afford [{kappa(P)-eta(6)-KITPHOS}RuCl2], the first example of a constrained-geometry complex in which the kappa(P)-bonded diphenylphosphino group and the eta(6)-coordinated proximal phenyl ring are connected by an unsaturated two-carbon tether; both complexes form efficient catalysts for the direct ortho arylation of 2-phenylpyridine and N-phenylpyrazole with a range of aryl chlorides.