Oxidative Coordination versus C 3 −C(O)Me Bond Cleavage in Acetylacetonate Iridium Complexes

Iridabicycles [Ir{κ 3 ‐N,C,O‐(pyC(H)=C(C(O)Me) 2 }(Cl)(L−L)](L−L=cod (cod=1,5‐cyclooctadiene), 1 a ; bipy (bipy=2,2’‐bipyridine), 1 b ) have been obtained by oxidative coordination of 3‐(pyridine‐2‐yl‐methylene)pentane‐2,4‐dione L1 , to the complexes [{Ir(μ‐Cl)(cod)} 2 ] and [{Ir(μ‐Cl)(coe) 2 } 2 ] (coe= cis ‐cyclooctene), the latter in the presence of bipy. Remarkably, cleavage of the C 3 −C(O)Me bond of L1 has instead been achieved in the reaction with [Ir(Cl)(dmb) 2 ] (dmb=2,3‐dimethylbutadiene), yielding a compound formulated as [Ir{κ 2 ‐N,C‐(pyC(H)C(C(O)Me))}(CO)(μ‐Cl)(Me)] 2 , 2 . Treatment of dimer 2 with DMSO or PMe 3 produced the complexes[Ir{κ 2 ‐N,C‐(pyC(H)C(C(O)Me)}(CO)Cl(Me)L] (L=DMSO, 3 a ; PMe 3 , 3 b ). Plausible mechanisms for the reactions leading to complexes 1 and 2 are proposed by means of DFT calculations.