SciPROP-R: An Effective Bisphosphine Ligand for the Chemo-Selective Iron-Catalyzed Suzuki-Miyaura Coupling of Alkyl Chlorides

Novel 2-substituted 1,3-bis[bis(3',5'-di-tert-butylphenyl)-phosphino]propanes (SciPROP-R; 1-R), as well as their iron complexes FeCl2(SciPROP-R) 2-R, are synthesized. Single crystal X-ray analysis and solution-phase Fe K-and L-edge XAS of 2-R reveals that these complexes maintain tetrahedral geometry and hence paramagnetic high-spin properties both in the solid state and in the solution phase. 31PNMR results demonstrate that the superior coordination ability of SciPROP-TB (1-TB) is due to the bulky tert-butyl group at position 2 of the propane-1,3-diyl linker of the ligand. These novel iron complexes catalyze Suzuki-Miyaura-type cross coupling under mild conditions. Notably, iron(II) chloride -1-TB complex (2 TB) exhibits excellent catalytic activity owing to the high coor dination ability and electron-donating nature of 1-TB, being effective for chemoselective cross coupling between various alkyl chlorides and arylboron compounds.