Activation of vinylic carbon–chlorine bond by nickel complexes supported with phosphine ligands

Abstract The vinylic C–Cl bonds of ortho -chlorinated cycloalkenyl aldehydes ( 1 – 4 ) and ortho -chlorinated cycloalkenyl acetal derivatives ( 5 – 6 ) were successfully activated by nickel(0) and nickel(II) complexes supported by trimethylphosphine ligands. Except one trans -five-coordinate nickel(II) chloride complex trans -[Ni(PMe 3 ) 2 Cl {(C 5 H 6 ) CH O}] ( 7 ) as a cyclometalation product with coordination of the aldehyde group, the other six four-coordinate nickel(II) chloride complexes trans -[Ni(PMe 3 ) 2 Cl {(C 5 H 6 ) CH O}] ( 8 ), trans -[Ni(PMe 3 ) 2 Cl {(C 6 H 8 ) CH O}] ( 9 ), trans -[Ni(PMe 3 ) 2 Cl {(C 6 H 7 Me meta ) CH O}] ( 10 ), trans -[Ni(PMe 3 ) 2 Cl {(C 6 H 7 Bu-t meta ) CH O}] ( 11 ), trans -[Ni(PMe 3 ) 2 Cl {(C 6 H 8 ) CH(OCH 2 CH 2 O)}] ( 12 ) and trans -[Ni(PMe 3 ) 2 Cl {(C 6 H 7 Bu-t- meta ) CH(OCH 2 CH 2 O)}] ( 13 ) as C–Cl bond activation products were obtained without coordination of the aldehyde groups. These complexes were characterized by IR and NMR. The crystal and molecular structures of complexes 8 , 9 and 12 were determined by single crystal X-ray diffraction.