Syntheses of N‐(Diphenylphosphanyl)‐2‐pyridylmethylamine and Its Use as a Ligand in Magnesium and Zinc Complexes

Abstract

AbstractThe metathesis reaction of lithium 2‐pyridylmethylamide with chloroalkanes and phosphanes yields N‐ and C‐substitution products depending on the electrophile. Thus, C‐alkylated 1‐amino‐1‐(2‐pyridyl)‐2,2‐dimethylpropane (1) and 1‐amino‐1‐(2‐pyridyl)‐2‐phenylethane (2) and N‐substituted N‐benzyl‐(2‐pyridylmethyl)amine (3) and N‐(diphenylphosphanyl)‐2‐pyridylmethylamine (4) are obtained. In [1·LiCl]2, molecule 1 binds to the lithium atom in a bidentate fashion. C‐ and N‐ substituted 2‐pyridylmethylamines are compared with quantum chemical methods. Lithiation of 4 and subsequent reaction with cloro‐diphenylphosphane yields N,N‐bis(diphenylphosphanyl)‐2‐pyridylmethylamine (5) with a planar amine nitrogen atom. Metallation of 4 with dibutylmagnesium leads to the formation of colorless (tetrahydrofuran)magnesium bis[N‐(diphenylphosphanyl)‐2‐pyridylmethylamide] (6) with a penta‐coordinate alkaline earth metal atom in a trigonal bipyramidal environment. In contrast to this observation, the reaction of 4 with dimethylzinc yields colorless methylzinc bis[N‐(diphenylphosphanyl)‐2‐pyridylmethylamide] (7). Zincation of 1 gives dimeric methylzinc 1‐(2‐pyridyl)‐2,2‐dimethyl‐1‐propylamide (8). In these zinc complexes the metal and amide nitrogen atoms are in distorted tetrahedral environments.