Development of Pincer Catalysts with Selected Group 8～10 Metals

Abstract

Pincer metal complexes have been widely applied in organic synthesis, organometallic catalysis and materials science. In this account, we trace our studies on the synthesis of pincer complexes of selected group 8~10 metals and their applications in catalytic reactions. Successful examples include achiral and chiral PCP pincer Pd(II) complexes, PCN pincer complexes of Pd(II) and Ni(II), bis(imidazolinyl)phenyl NCN pincer complexes of Pd(II), Pt(II), Ni(II), Rh(III) and Ir(III), NCN' pincer Pd(II) complexes and CNN' pincer complexes of Pd(II) and Ru(II), which are conveniently prepared from easily available starting materials via direct Caryl—H bond activation. Particularly, a one-pot phosphorylation/metalation strategy was developed, providing a new and facile approach for the preparation of PCP and PCN pincer metal complexes. The method avoids the troublesome isolation of the unstable P-containing ligands and meanwhile accomplishes the metalation of the related ligands central C—H bond in good yields, and the synthetic procedures are thus simplified. The obtained pincer metal complexes have been used as catalysts in various C—C bond-forming reactions including the asymmetric ones, transfer hydrogenation of ketones and asymmetric hydrophosphination. The related literature results are also presented.