Syntheses of bimetallic rare-earth bis(cyclopentadienyl) derivatives supported by bridged bis(guanidinate) ligands and their catalytic property for the hydrophosphonylation of aldehydes

•Five new bimetallic organo-rare-earth metal complexes were synthesized.•The structures were elucidated by X-ray crystallography.•These complexes showed high catalytic activity for hydrophosphonylation reaction under mild conditions.

Some bimetallic rare earth bis(cyclopentadienyl) derivatives supported by bridged bis(guanidinate) ligands {(C5H5)2RE[(RN)2CN(CH2)2]}2 [R = iPr, RE = Yb(1), Er(2), Y(3); R = Cy, RE = Yb(4)] and {(CH3C5H4)2Sm[(iPrN)2CN(CH2)2]}2 (5) were prepared by the reaction of lithium guanidinate {Li[(RN)2CN(CH2)2]}2 (R = iPr, Cy) with (C5H5)2RECl (RE = Yb, Er, Y) or (CH3C5H4)2SmCl in a 1:2 M ratio in THF. Complexes 1–5 were confirmed by elemental analyses, IR spectra and NMR spectroscopy (for complex 3). The molecular structures of complexes 1–3 and 5 were provided by X-ray structure diffraction, which indicated that these complexes have similar dinuclear solid state structure. The rare-earth ion in these complexes is bonded to two η5-cyclopentadienyl rings and one chelating guanidinate ligand. It was found that these rare-earth metal complexes are efficient catalysts for the hydrophosphonylation of various aldehydes, to generate α-hydroxyphosphonates in high yields under mild reaction conditions.

Graphical abstractSome bimetallic rare earth bis(cyclopentadienyl) derivatives supported by bridged bis(guanidinate) ligands were prepared, which showed high activity for the hydrophosphonylation of aldehydes under mild reaction conditions, to generate α-hydroxyphosphonates.Figure optionsDownload full-size imageDownload as PowerPoint slide