A rare earth alloy as a synthetic reagent: contrasting homometallic rare earth and heterobimetallic outcomes

Abstract

Reaction of LaNi₅ with 2,2′-dipyridylamine (HNpy₂) at 170 °C under vacuum gave crystals of dimeric [La(Npy₂)₃]₂ as a previously unknown eight-coordinate isomer (1a) (two μ-η²:η² and two terminal chelating (N_amide,N_py) Npy₂ ligands), which reverts to the known ten coordinate isomer (1b) on recrystallisation from THF/PhMe, thereby establishing linkage isomerism of a [Ln(Npy₂)₃]₂ complex for the first time. Reaction of 8-hydroxyquinoline (HOQ) with excess LaNi₅ alloy at 190 °C resulted in extraction of both metals and the formation of heterobimetallic [Ni₂La(OQ)₇] (2). The trinuclear complex has two terminal, fac-octahedral nickel(II) sites, each bound to three chelating 8-quinolinolate anions which bridge through the oxygen atoms to the lanthanum(III) centre. The eight-coordinate lanthanum environment is completed by a chelating OQ ligand.