Masked Divalent Reactivity of Heterobimetallic Lanthanide Isocarbonyl Complexes
Arpan Mondal1, Jinkui Tang2, Richard A Layfield1
1Department of Chemistry, School of Life Sciences, University of Sussex, BN1 9RH, Brighton, U.K.
Abstract:
A new rare-earth reduction system is described in which trivalent yttrium and dysprosium react as though present in their unstable divalent oxidation state. This masked divalent reactivity is achieved using the isocarbonyl-bridged dimers [( M)(μ-Fp)]2 (M=Y, 1Y; M=Dy, 1Dy; Cpttt=1,2,4-C5 tBu3H2; Fp=CpFe(CO)2), where the reducing electrons originate from the bridging [Fp]- ligands. The reactivity of 1Y and 1Dy is showcased by reducing the N-heterocycles 2,2'-bipyridyl (bipy), phenazine (phnz) and hexaazatrinaphthylene (HAN) to give corresponding mono-, di- and tri-metallic rare-earth complexes, respectively, with the heterocyclic ligands present in their singly, doubly and triply reduced forms, respectively. The dynamic magnetic properties of the dysprosium compounds are described. Compound 1Dy is a single-molecule magnet (SMM) with an appreciable energy barrier of 449(17) cm-1, whereas [( Dy)2(μ-phnz)] (3Dy) is not an SMM because of a strong, competing equatorial crystal field. Surprisingly, [( Dy)3(HAN)] (4Dy) is also not an SMM, the origins of which are traced to the impact of the tert-butyl substituents on the dysprosium centre and its interaction with the radical [HAN]3- ligand.
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