Taming salophen in rare earth metallocene chemistry

A series of multinuclear metallocenes composed of a tBusalophen dianion bound to two rare earth metal ions{,} where each is encased in a bis-pentamethylcyclopentadienyl scaffold{,} was realized. The isolated molecules (Cp*2RE)2(μ-tBusalophen){,} where RE = Gd (1){,} Dy (2){,} and Y (3){,} constitute the first salophen-bridged metallocene complexes for any metal ion. 1–3 were characterised by X-ray crystallography{,} cyclic voltammetry{,} IR{,} NMR{,} and UV-Vis-NIR spectroscopy. Cyclic voltammograms of 1–3 excitingly exhibit quasi-reversable features attributed to the (tBusalophen2−/tBusalophen3−˙) redox couple. DFT calculations on 3 uncovered the highest occupied molecular orbital to be primarily localized on the metallocene and phenolate moieties of the tBusalophen ligand. Furthermore{,} the nuclear spin I = ½ for yttrium allowed the collection of 89Y NMR spectra for 3. Magnetic studies revealed slow magnetic relaxation{,} placing 2 among dysprosocenium-based single-molecule magnets containing a doubly anionic ligand in the equatorial plane.