Isocyanate diinsertion into the N–H bond of the 2-pyridylamino ligand of organolanthanides

Abstract

[Cp₂LnNHPy]₂ (Py = 2-pyridyl) (1a–e) react with phenyl isocyanate to form the N–H diinsertion products Cp₂Ln[η²:η¹-PyNCON(Ph)CONHPh](THF) (Ln = Yb (3a), Er (3b), Y (3c), Dy (3d), Gd (3e)). It has been proven that ⁿPr₂NH can abstract one PhNCO unit from 3c to form Cp₂Y[η³-OC(NHPh)NPy] (2c) and ⁿPr₂NHCONHPh (4), representing a rare example of selective release of a functional group of ligands in organolanthanide chemistry. Hydrolysis of 2c gives the organic nitrogen-containing product PyNHCONHPh (5). Moreover, 3c can also be obtained by the reaction of 2c with PhNCO. These results demonstrate that the diinsertion of PhNCO into the N–H bond of coordinated amino ligands might proceed in a stepwise manner. All the compounds were characterized by elemental analysis and spectroscopic properties. The structures of compounds 3a–e and 4 are also determined through X-ray single-crystal diffraction analysis.