Synthesis and application of novel ionic phosphine ligands with a cobaltocenium backbone

Six novel ionic phosphine ligands with a cobaltocenium backbone, 1,1′-bis(dicyclohexylphosphino) cobaltocenium hexafluorophosphate (View the MathML sourcedi-cypc+PF6-) (1a), 1,1′-bis(di-iso -propylphosphino) cobaltocenium hexafluorophosphate (View the MathML sourcedi-isoppc+PF6-) (2a), 1,1′-bis(di-tert -butylphosphino) cobaltocenium hexafluorophosphate (View the MathML sourcedi-tbpc+PF6-) (3a), and the monophosphine ligand View the MathML sourceCc+PR2PF6- (Cc+ = cobaltocenium; R = Cy, 1b; R = i -Pr, 2b; R = t -Bu, 3b) were synthesized and characterized by elemental analysis, spectroscopy, and X-ray diffraction techniques. These ligands are air-stable and useful for Suzuki coupling reactions in the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (View the MathML sourceBMIM+PF6-), enabling high catalytic activity.