Affiliation:
1. Inorganic and Organometallic Chemistry Universität Erlangen-Nürnberg Egerlandstrasse 1 91058 Erlangen Germany
2. Eenheid Algemene Chemie (ALGC) Vrije Universiteit Brussel (VUB) 1050 Brussels Belgium
3. Department of Chemistry University of Warwick Gibbet Hill Road Coventry CV4 7AL UK
4. Institut de Química Computacional i Catàlisi Departament de Química Universitat de Girona C/ Maria Aurèlia Capmany 69 17003 Girona Catalonia Spain
Abstract
AbstractInverse sandwich complexes of Yb and Sm stabilized by a bulky β‐diketiminate (BDI) ligand have been prepared: (BDI)Ln(η6,η6‐C6H6)Ln(BDI); Ln=lanthanide. Coordinated benzene ligands can be neutral, di‐anionic or, often controversially discussed, even tetra‐anionic. The formal charge on benzene is correlated to assignment of the metal oxidation state which generally poses a problem. Herein, we take advantage of the structural similarities found when comparing CaII with YbII, and SrII with SmII complexes. In this work, we found an excellent overlap of the Ca/Yb inverse sandwich structures but a striking difference for the Sr/Sm pair. The much shorter Sm−N and Sm‐C6H6 distances are strong evidence for a SmIII‐benzene−4‐SmIII assignment. This was further supported by NMR spectroscopy, magnetic susceptibility, reactivity and comprehensive computational investigation.