A Molecular Barium Hydrido Complex Stabilized by a Super-Bulky Hydrotris(pyrazolyl)borate Ligand.

Hydrogenolysis of the scorpionate-supported barium alkyl complex (TpAd,iPr )Ba[CH(SiMe3 )2 ](THF) (TpAd,iPr =hydrotris(3-adamantyl-5-isopropyl-pyrazolyl)borate) afforded the dinuclear barium hydrido complex [(TpAd,iPr )Ba(μ-H)]2 (2), which was characterized by NMR spectroscopy and single-crystal X-ray analysis. Exposure of 2 with 1 atm of CO resulted in a reductive coupling process to form the cis-ethendiolate dianion (3). Reaction of 2 with one equivalent of PhC≡C-C≡CPh gave barium 1,4-diphenyl-2-butyne-1,4-diyl complex {[(TpAd,iPr )Ba]2 (PhCH-C≡C-CHPh) (4).