Bis- and Mono(amidate) Complexes of Yttrium: Synthesis, Characterization, and Use as Precatalysts for the Hydroamination of Aminoalkenes

Abstract

A high-yielding synthetic route is disclosed for yttrium bis- and mono(amidate) complexes using the reaction of amide proligand and Y(N(SiMe3)2)3 starting materials. The structure, bonding, and solution phase characterization data for this new class of complexes are presented. The modular nature of the amidate ligand allows for easy addition of electron-withdrawing CF3 groups in the ligand backbone to tune electronic properties of the resulting precatalysts. The amidate ligands in the bis(amidate) complexes were found to be highly fluxional on the NMR time scale, while the mono(amidate) yttrium complex required heating to 110 °C before ligand redistribution was observed. Three bis(amidate) complexes with differing electronic properties and one mono(amidate) complex have been used as precatalysts for hydroamination using a wide range of aminoalkene substrates. Bis(amidate) complexes bearing the more electron-withdrawing amidate ligands were found to be the most active precatalysts for intramolecular alkene hydroamination.