Synthesis and Characterization of Phosphanophenolate-Based Rare-Earth Metal–Copper Complexes

The reaction of [LnIII(OArP-κ2O,P)3] (1-Ln, Ln = La, Sm, Y, Yb, and ArPO– = 2,4-tBu2-6-(Ph2P)C6H2O–) with the copper(I) triflate toluene adduct yields the corresponding dinuclear rare-earth metal(III)–copper(I) complexes [LnIII(OTf)(μ-OArP-1κ1O,2κ1P)3CuI] (2-Ln, Ln = La, Sm, Y, Yb) in clean conversion. In order to explore an alternative synthetic route by starting from a mononuclear copper complex instead of a rare-earth metal complex, the mononuclear copper complex [(HOArP-κP)3CuIOTf] (3) was prepared from copper(I) triflate toluene adduct and HOArP. However, the reaction of 3 with [LnIII[N(SiMe3)2]3] (Ln = La, Y) gave the heterobimetallic complexes only in low yields, along with undesired side-products. Investigation into the exchange of the triflate in 2-Ln for different groups was explored using alkaline metal amides, alkyls, and alkoxides and was successful only for reactions with KOtBu, yielding [LnIII(OtBu)(μ-OArP-1κ1O,2κ1P)3CuI] (4-Ln, Ln = La, Sm, Y, Yb). The compounds 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.