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(mu-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 equivalent to C-C equivalent to CPh gave barium 1,4-diphenyl-2-butyne-1,4-diyl complex {[(Tp(Ad,iPr))Ba](2)(PhCH-C equivalent to C-CHPh) (4).