Oxidative Addition of C–X Bonds and H–H Activation Using PNNP‐Iron Complexes

Iron(0) complex bearing a phenanthroline‐based meridional PNNP ligand [{Fe(PNNP)}2(μ‐N2)] (1) (PNNP=2,9‐bis((diphenylphosphino)methyl)‐1,10‐phenanthroline) smoothly reacted with CH3I at ambient temperature to cleave C–I bond, resulting in the formation of the corresponding oxidative addition product, [Fe(CH3)(I)(PNNP)] (2). Complex 2 was fully identified by NMR and its structure was determined by a single crystal X‐ray diffraction study. Mechanistic study using cyclopropylmethyl bromide as a radical clock supported a radical pathway for the C–I bond cleavage of CH3I. Complex 2 underwent deprotonation on treatment with NaOtBu to form 4, which possessed a dearomatized phenanthroline backbone. Complex 4 further reacted with H2 to cleave H–H bond. The reaction was mediated by metal‐ligand cooperation process that involves re‐aromatization of the phenanthroline backbone of the PNNP ligand. Iron(0) complex bearing a phenanthroline‐based meridional PNNP ligand [{Fe(PNNP)}2(μ‐N2)] (1) reacted with CH3I to form the corresponding oxidative addition product, [Fe(CH3)(I)(PNNP)] (2). On treatment of NaOtBu, 2 underwent dearomatization of the phenanthroline backbone. The resulting complex further reacted with H2 to cleave H−H bond. The reaction was mediated by metal‐ligand cooperation process that involves rearomatization of the phenanthroline backbone of the PNNP ligand.