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

Hydrogenolysis of the scorpionate-supported barium alkyl complex (Tp^Ad,iPr)Ba[CH(SiMe3)2](THF) (Tp^Ad,iPr = hydrotris(3-adamantyl-5-isopropyl-pyrazolyl)borate) afforded the dinuclear barium hydrido complex [(Tp^Ad,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 PhCC-CCPh gave barium 1,4-diphenyl-2-butyne-1,4-diyl complex {[(Tp^Ad,iPr)Ba]2(PhCH-CC-CHPh) (4).