New Asymmetric Iminophosphonamide Ligand and Its Yttrium Complex: Synthesis and Crystal Structure

Asymmetric aminoiminophosphorane Ph₂P(NHPbt)(=NMes) (HL) is synthesized by the reaction of Pbt–NHPPh₂ and MesN₃ (Pbt = 2-(benzothiazol-2-yl)phenyl; Mes = mesityl). Then it is used to obtain [Y(L)Cl₂(THF)] complex (1, THF - tetrahydrofuran). The compounds are isolated as crystalline phases: HL, HL·0.5PhMe, 1, and 1·PhMe. They are characterized by single crystal X-ray diffraction, NMR, and IR techniques. A hydrogen bond between the hydrogen atom of the NH group bonded to Pbt and the nitrogen atom of the heterocycle is present in HL. In complex 1, all three nitrogen atoms of the ligand coordinate to the yttrium cation and form a planar structure of chelate rings. The π-stacking is observed between the aromatic moieties of the molecules in both HL and complex 1.