Oxidation-reduction exchange of 2-acylenolato and trimethylphosphane ligands between d8 complexes of nickel and cobalt

Abstract A series of seven (C:O)-dianionic 1-acyl-2-enolato ligands C(O)CCO in a redistribution reaction between 18-electron metal-d 8 complexes Ni[C(O)CCO](PMe 3 ) 3 [CC=3-CMe 3 -5-Me-C 6 H 2 ( 1 ), 3,5-CMe 3 C 6 H 2 ( 2 ), 3,4-benzo-cyclohexene ( 3 ), 5-phenyl-cyclohexene ( 4 ), 5- tert -butyl-cyclohexene ( 5 ), cyclohexene ( 6 ), 1,2-diphenylethene ( 7 )] and Co(CCPh)(PMe 3 ) 4 (1:1) have been transferred to cobalt to afford the novel compounds mer - trans -Co[C(O)CCO](CCPh)(PMe 3 ) 3 ( 8 – 14 ) in stoichiometric reactions and transforming the nickel into Ni(PMe 3 ) 4 . In the X-ray crystal structure of the parent nickel compound 7 , the 2-acylenolato ligand is seen to span C-axial and O-equatorial positions in a distorted trigonal bipyramid. The molecular structure of compound 14 shows an octahedral coordination of cobalt: a chelate ring accurately retaining angles and bond distances, and an alkynyl ligand occupying the position opposite to the O-donor function.