Synthesis and characterization of ytterbium guanidinates stabilized by bridged bis(phenolate) ligand and their application for the hydrophosphonylation reaction of aldehydes

•Four ytterbium guanidinates bearing bridged bis(phenolate) ligand were prepared.•The solid state structures of all four complexes were determined by X-ray diffraction analysis.•Ytterbium guanidinates showed high activities in catalyzing hydrophosphonylation reactions of aldehydes.

A series of ytterbium guanidinato complexes stabilized by an amine-bridged bis(phenolate) ligand were prepared, and their catalytic property for the hydrophosphonylation reaction of aldehydes was explored. Metathesis reactions of amine-bridged bis(phenolate) ytterbium chlorides LYbCl(THF) [L = Me2NCH2CH2N{CH2-(2-OC6H2tBu2-3,5)}2] with corresponding lithium guanidinates in a 1:1 molar ratio in THF gave the expected ytterbium guanidinato complexes LYb[R2NC(NR1)2] [R1 = Cy, R2N = N(TMS)2 (1), N(CH2)5 (2); R1 = iPr, R2N = N(TMS)2 (3), NPh2 (4)]. These ytterbium complexes were well characterized by elemental analyses, IR spectroscopy and single-crystal X-ray structure determination. The metal ion is six-coordinated by two oxygen and two nitrogen atoms from the bis(phenolate) ligand, and two nitrogen atoms from one guanidinato group. The coordination geometry around ytterbium can be described as a distorted octahedron. It was found that these ytterbium guanidinato complexes are highly efficient catalysts for the hydrophosphonylation reaction of various aldehydes under mild conditions.

Graphical abstractFour ytterbium guanidinato complexes stabilized by an amine-bridged bis(phenolate) ligand were prepared, which showed very high activity for the hydrophosphonylation of aldehydes with diethyl phosphite under mild reaction conditions.Figure optionsDownload full-size imageDownload as PowerPoint slide