Structures and catalytic properties of triphenylphosphine oxide complexes of scandium and lanthanide triflates

Abstract

The complexes M(OTf) 3(Ph 3PO) 4 where M=lanthanide metals and scandium have been prepared and characterised in the solid state by single crystal X-ray diffraction, infrared spectroscopy and elemental analysis. All the complexes have the ionic structure [M(OTf) 2(Ph 3PO) 4] +[OTf] −. Single crystal X-ray structures for M=Sc, Nd and Lu are reported. In the complexes of the early lanthanides (LaNd) the metals are seven-coordinate with one monodentate, one bidentate triflate. The smaller lanthanide ions, and scandium, have six-coordinate structures with an approximate octahedral coordination about the metal where both triflates are bound as monodentate ligands. The solution structures have been analysed by electrospray mass spectrometry, which indicates that extensive ligand redistribution occurs. The complexes catalyse the Friedel Crafts acylation, alkenylation and alkylation of activated aromatics with modest increases in selectivity compared to the same reactions using scandium triflate.