Synthesis and Reactivity of Discrete Europium(II) Hydride Complexes.

The bulky β-diketiminate ligand frameworks [BDI DCHP ] - and [BDI Dipp/Ar ] - (BDI=[HC{C(Me) 2 N-Dipp/Ar} 2 ] - (Dipp=2,6-diisopropylphenyl (Dipp); Ar=2,6-dicyclohexylphyenyl (DCHP) or 2,4,6-tricyclohexylphyenyl (TCHP)) have been developed for the kinetic stabilisation of the first europium (II) hydride complexes, [(BDI DCHP )Eu(μ-H)] 2 , [(BDI Dipp/DCHP )Eu(μ-H)] 2 and [(BDI Dipp/TCHP )Eu(μ-H)] 2 , respectively. These complexes represent the first step beyond the current lanthanide(II) hydrides that are all based on ytterbium. Tuning the steric profile of β-diketiminate ligands from a symmetrical to unsymmetrical disposition, enhanced solubility and stability in the solution-state. This provides the first opportunity to study the structure and bonding of these novel Eu(II) hydride complexes crystallographically, spectroscopically and computationally, with their preliminary reactivity investigated.