Synthesis and Characterisation of Phosphanophenolate-based Rare-Earth Metal-Copper Complexes

The reaction of rare-earth metal(III) tris[2,4-di-tert-butyl-6-(diphenylphosphanyl)phenolate] complexes (1-Ln, Ln = La, Sm, Y, Yb) with copper(I) triflate toluene adduct yield the corresponding dinuclear ra-re-earth metal(III) triflate tris[2,4-di-tert-butyl-6-(diphenylphosphanyl)phenolate] copper(I) complexes (2-Ln, Ln = La, Sm, Y, Yb) in clean conversion. In order to explore an alternative synthetic route by starting from mononuclear copper complex instead of a rare-earth metal complex, the mononuclear complex tris[2,4-di-tert-butyl-6-(diphenylphosphanyl)phenol] copper(I) triflate (3) was prepared from copper(I) triflate toluene adduct and 2,4-di-tert-butyl-6-(diphenylphosphanyl)phenol. However, the re-action of 3 with rare-earth metal(III) tris[bis(trimethylsilyl)amide] gave the heterobimetallic complexes 2-Ln only in low yields along with undesired side-products. Investigation into the exchange of the tri-flate in 2-Ln for different groups was explored using alkaline metal amides, alkyls, and alkoxides and successful only for potassium tert-butanolate yielding rare-earth metal(III) tert-butanolate tris[2,4-di-tert-butyl-6-(diphenylphosphanyl)phenol] copper(I) complexes (4-Ln, Ln = La, Sm, Y, Yb). The com-pounds were characterized by NMR, UV-Vis, and IR spectroscopy, single-crystal X-ray diffraction, and elemental analysis. The effective magnetic moments of the paramagnetic complexes were determined via the Evans NMR method.