Synthesis and reactivity of (chlorovinyl)nickel complexes: An unusual symmetrization reaction. X-ray crystal structure of [Ni(CCl=CCl2)2(PMe2Ph)2]

Article abstract of DOI:10.1021/om00085a006

The oxidative addition of CCl₂=CCl₂, CCl₂=CHCl, trans-CHCl=CHCl, and CH₂=CCl₂ to [Ni(PPh₃)_n], prepared in situ from NiCl₂, PPh₃, and NaBH₄, gives square-planar trans-[NiCl]chlorovinyl)(PPh₃)₂]. The addition takes place at the less hindered C-Cl bond, with retention of geometry. The PPh₃ ligand is replaced by dppe in [NiCl(C₂Cl₃)(PPh₃)₂] giving [NiCl(C₂Cl₃)dppe] whereas the action of N-donor bidentate ligands gives a symmetrization reaction, forming [NiCl₂(LL)] and [Ni(C₂Cl₃)₂(LL)] (LL = 2,2′-bpy and o-phen). The ligand bpy may be replaced by phosphines like PMe₂Ph and PEt₃ in the trichlorovinyl complex. The crystal structure of trans-[Ni(C₂Cl₃)₂(PMe₂Ph) ₂] (monoclinic, space group P2₁/c, a = 9.203 (2) ?, b = 16.005 (3) ?, c = 9.604 (2) ?, β = 114.79 (3)°, Z = 2) shows the presence of the anti and syn isomere in the solid. The Ni-P bond distance and the mean Ni-C bond distance are 2.201 (1) and 1.91 (1) ?, respectively. ³¹P and ¹³C NMR spectra indicate that similar amounts of syn and anti isomers are present in solution.