A two‐step synthesis allows the preparation of α‐(2‐pyridyl)benzylamine (1) in good yield. Phosphanylation in the presence of triethylamine gives (diphenylphosphanyl)α‐(2‐pyridyl)benzylamine (2), ...which crystallizes as a racemate in the centrosymmetric triclinic space group P$\bar {1}$. The P–N bond lengths exhibit an average value of 168.3 pm. Lithiation of 2 with n‐butyllithium yields dimeric semi(tetrahydrofuran)lithium (diphenylphosphanyl)α‐(2‐pyridyl)benzylamide (3) with the lithium atoms in different environments. One Li atom is in a distorted tetrahedral environment and the other in a trigonal‐planar coordination sphere with bridging amide moieties (av. Li–N 201.8, Li–O 192.4 pm). Zincation of 2 with dimethylzinc leads to the formation of dimeric methylzinc (diphenylphosphanyl)α‐(2‐pyridyl)benzylamide (4) with a central six‐membered (ZnNP)2 ring in a boat conformation (av. Zn–N 201.8, Zn–P 245.9 pm). The endocyclic P–N bonds are rather short (av. value 162.7 pm).
(2‐Pyridylmethyl)amide anions act as bidentate chelate ligands. N‐(Diphenylphosphanyl) substitution extends the coordination behavior. The hard lithium cation exclusively binds to the nitrogen donors, whereas methylzinc (diphenylphosphanyl)(2‐pyridylmethyl)amide dimerizes through bridging amide and phosphanyl moities (Zn red, P orange, N blue; C hollow spheres; H omitted).
Metallation of N‐(diphenylphosphanyl)(2‐pyridylmethyl)amine with n‐butyllithium in toluene yields lithium N‐(diphenylphosphanyl)(2‐pyridylmethyl)amide (1), which crystallizes as a tetramer. ...Transamination of N‐(diphenylphosphanyl)(2‐pyridylmethyl)amine with an equimolar amount of SnN(SiMe3)22 leads to the formation of monomeric bis(trimethylsilyl)amido tin(II) N‐(diphenylphosphanyl)(2‐pyridylmethyl)amide (2). The addition of another equivalent of N‐(diphenylphosphanyl)(2‐pyridylmethyl)amine gives homoleptic tin(II) bisN‐(diphenylphosphanyl)(2‐pyridylmethyl)amide (3). In these complexes the N‐(diphenylphosphanyl)(2‐pyridylmethyl)amido groups act as bidentate bases through the nitrogen bases. At elevated temperatures HN(SiMe3)2 is liberated from bis(trimethylsilyl)amido tin(II) N‐(diphenylphosphanyl)(2‐pyridylmethyl)amide (2) yielding mononuclear tin(II) 1,2‐dipyridyl‐1,2‐bis(diphenylphosphanylamido)ethane (4) through a C–C coupling reaction. The three‐coordinate tin(II) atoms of 2 and 4 adopt trigonal pyramidal coordination spheres.
The 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·LiCl2, 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 bisN‐(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 bisN‐(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.
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