Divalent Ytterbium Hydrido Complex Supported by a β-Diketiminato-Based Tetradentate Ligand: Synthesis, Structure, and Reactivity

While the chemistry of trivalent rare-earth metal hydrido complexes has been well developed in the past 40 years, that of the divalent rare-earth metal hydrido complexes remains in its infancy because of the synthetic challenge of such complexes. In this paper, we report the synthesis and structural characterization of a divalent ytterbium hydrido complex supported by a bulky beta-diketiminato-based tetradentate ligand. This hydrido complex is a dimer containing two mu-hydrogen ligands, and it easily undergoes a hydrido shift reaction to form a new divalent ytterbium hydrido complex that contains only one hydrido bridge. Furthermore, this hydrido complex reacts with pyridine and pyridine derivatives, showing versatile reactivity [Yb-H addition to pyridine, hydrido shift to ancillary ligand, and ytterbium(II)-center-induced redox reaction with bipyridine]. This hydrido complex reacts with Ph3P=O, resulting in a P-C-Ph cleavage of Ph3P=O and an elimination of C6H6; on the other hand, the reaction with Ph3P=S is a hydrido coupling-based redox reaction. The reactions of this hydrido complex with 1 and 2 equiv of PhSSPh clearly indicate that the hydrido coupling-based redox reaction is prior to the ytterbium(II) oxidation-based redox reaction.

Automated summary

In this paper, the synthesis and structural characterization of a divalent ytterbium hydrido complex supported by a bulky beta-diketiminato-based tetradentate ligand are reported. This hydrido complex shows versatile reactivity, undergoing hydrido shift reactions and reacting with various compounds such as pyridine and pyridine derivatives. The reactions of this hydrido complex with Ph3P=O and Ph3P=S demonstrate different redox reactions, with the hydrido coupling-based redox reaction found to occur prior to the ytterbium(II) oxidation-based redox reaction when reacted with PhSSPh.