Preparation of Five-Membered Nickelacycles with Anionic C−N−N‘ Terdentate Ligands. X-ray Crystal Structure of [NiCl{2-(CHNCH₂CH₂NMe₂)-3-ClC₆H₃}]

Abstract

The five-membered metallacycles [Ni(C−N−N‘)X] have been prepared by oxidative addition of o -halo-substituted imines derived from N, N -dimethylethylenediamine, C 6 R n H 5 - n CH NCH 2 CH 2 NMe 2 to [Ni(COD) 2 ]. The molecular structure of [NiCl{2-(CH NCH 2 CH 2 NMe 2 )-3-ClC 6 H 3 }] has been determined by a single-crystal X-ray crystallographic study. Some ionic compounds [Ni(C−N−N‘)L]BF 4 (L = NCMe, heterocyclic amines) were also obtained. The Ni C bond of these complexes is inert toward insertion reactions of ethylene or PhC⋮CPh. The action of [Ni(COD) 2 ] on the diamines C 6 R n H 5 - n CH 2 N(Me)CH 2 CH 2 NMe 2 affords highly insoluble organonickel derivatives, which by reaction with aromatic amines (L) in the presence of TlBF 4 lead to the ionic derivatives [Ni(C−N−N‘)L]BF 4 . The stabilization of organometallic Ni(III) compounds using CuCl 2 as oxidant was not achieved. Coordination compounds [NiClBr(N‘−N)], where N−N‘ = 2-ClC 6 H 4 CH 2 N(Me)CH 2 CH 2 NMe 2, were formed probably by reductive elimination of Ni(III) species followed by reoxidation to Ni(II).