Terminal nickel(II) amide, alkoxide, and thiolate complexes containing amido diphosphine ligands of the type [N(o-C6H4PR2)(2)](-)(R=Ph,Pr-i,Cy)

摘要

A series of nickel(II) complexes of the type [R-PNP] Ni(ER') ([R-PNP](-) = [N(o-C6H4PR2)(2)](-); R = Ph, Pr-i, Cy; E = NH, O, S; R' = Ph, Bu-t) featuring unsupported, covalently bound pi-donor ligands have been prepared and characterized. The metathetical reactions of [ R- PNP] NiCl (R = Ph, Pr-i, Cy) with LiNHPh, NaOPh, or NaSPh, respectively, produced the corresponding anilide [ R- PNP] Ni( NHPh), phenolate [ R- PNP] Ni( OPh), and thiophenolate [ R- PNP] Ni( SPh) derivatives. Treatment of [ Ph-PNP] NiCl with either (LiNHBu)-Bu-t or (NaOBu)-Bu-t generated tert-butyl amide [ Ph- PNP] Ni( NHtBu) and tert-butoxide [ Ph- PNP] Ni( OtBu), respectively. In contrast, attempts to prepare analogous tert-butyl amide and tert-butoxide complexes of [Pr-i- PNP](-) or [Cy-PNP](-) were not successful. Protonolysis studies of these nickel( II)- heteroatom complexes revealed the basic reactivity of these pi-donor ligands. The basicity follows the order (NHBu)-Bu-t > (OBu)-Bu-t > NHPh > OPh > SPh. In addition to solution NMR spectroscopic data for all new compounds, X-ray structures of [ Pr-i- PNP] Ni( NHPh) and [Pr-i- PNP] Ni( OPh) are presented.