Group 10 metal complexes of the 3,4-bis(dicyclohexylphosphino)thiophene (dcypt) ligand: Synthesis, characterization and catalysis

The nickel(II) ( 1 ), palladium(II) ( 2 ) and platinum(II) ( 3 ) complexes of the 3,4-bis(dicyclohexylphosphino)thiophene ( dcypt ) ligand were synthesized and characterized by multinuclear NMR and FT-IR spectroscopic techniques, mass spectrometry and elemental analysis. The nearly perfect square-planar geometry of the three complexes was confirmed by single-crystal X-ray diffraction analysis. Both complexes 1 (Ni) and 2 (Pd) were evaluated towards the Suzuki-Miyaura cross-coupling reaction between aryl halides and aryl boronic acids, a field that was not explored until now for metal complexes of dcypt . While the palladium(II) (pre)catalyst ( 2 ) was found very efficient for this transformation, both under “classical” (Cs 2 CO 3 as base, 1,4-dioxane as solvent) and “green” (K 3 PO 4 as base, tert -amyl alcohol ( t AA) as solvent) reaction conditions, its nickel(II) analog ( 1 ) was only moderately active under the latter conditions (inactive under the former). Complex 2 was tolerant to both the presence of EDGs or EWGs groups on para position of the aryl halide or aryl boronic acid (72- > 99 %) and allowed the synthesis of polycyclic aromatic compounds. Moreover, the remarkable air-stability of dcypt and of its corresponding palladium(II) complex ( 2 ) allowed to perform Suzuki-Miyaura cross-coupling reactions under air and with a non-dried alcoholic solvent ( t AA) without loss of activity. • Group 10 metal complexes of the 3,4-bis(dicyclohexylphosphino)thiophene ligand. • Characterization by multinuclear NMR, FT-IR, MS, EA and X-ray crystallography. • Direct comparison between NiCl 2 (dcypt) and Pd Cl 2 (dcypt) (pre)catalysts. • Pd-catalyzed Suzuki-Miyaura cross-coupling under green conditions. • High tolerance towards electron withdrawing and electron donating groups.