1,3-Dinitrone Pincer Complexes of Palladium and Nickel: Synthesis, Structural Characterizations, and Catalysis

Neutral and cationic Pd(II) and Ni(II) OCO-type pincer complexes have been synthesized from the metalation of 1,3-dinitrones via C-H or C-Br bond activation using Pd(0), Pd(II), and Ni(0) starting materials. In each complex, the two six-membered metallacycles are non-coplanar and atropisomerization proceeds with a low barrier. Palladium dinitrone complexes have been shown as active catalysts for Heck couplings and the related Ni complex for Kumada reactions with turnover numbers up to 950 000.