Stoichiometric and catalytic C-Cl activation of Aryl Chlorides using an NHC-stabilized nickel(0) complex

[Ni-2((i)Pr(2)Im)(4)(COD)] 1 catalyzes the Suzukie-Miyaura-type cross coupling reaction of chlorobenzene and phenylboronic acid efficiently. Compound 1 compares well with other nickel catalyst reported so far with the advantage that no further excess of ligand such as PPh3 has to be added. Oxidative addition of different aryl chlorides to complex 1 is highly selective for a broad range of substrates, ranging from activated to deactivated aryl chlorides. The stoichiometric reaction of 1 with aryl chlorides (ArCl) afforded complexes of the type trans-[Ni((i)Pr(2)Im)(2)(Cl)(Ar)] (for Ar = Ph 2, 4-Me(O)CC6H4 3, 4-H(O) CC6H4 4, 4-MeOC6H4 5, 4-H2NC6H4 6, 4-F3CC6H4 7, 4-ClC6H4 8, 3-ClC6H4 9, 2-ClC5NH3 10 4-FC6H4 11). All resulting nickel(II) complexes have been fully characterized, in most cases including X-ray diffraction. In contrast to the work described by Matsubara and coworkers just recently on the sterically slightly more demanding [Ni(Dip(2)Im)(2)] system, we have found for the [Ni((i)Pr(2)Im)(2)] complexes no indication for the formation of three coordinated nickel(I) complexes. (C) 2011 Elsevier B.V. All rights reserved.