Simple Access to the Heaviest Alkaline Earth Metal Hydride: A Strongly Reducing Hydrocarbon-Soluble Barium Hydride Cluster.

Reaction of Ba[N(SiMe ) ] with PhSiH in toluene gave simple access to the unique Ba hydride cluster Ba H [N(SiMe ) ] that can be described as a square pyramid spanned by five Ba ions with two flanking BaH[N(SiMe ) ] units. This heptanuclear cluster is well soluble in aromatic solvents, and the hydride H NMR signals and coupling pattern suggests that the structure is stable in solution. At 95 °C, no coalescence of hydride signals is observed but the cluster slowly decomposes to undefined barium hydride species. The complex Ba H [N(SiMe ) ] is a very strong reducing agent that already at room temperature reacts with Me SiCH=CH , norbornadiene, and ethylene. The highly reactive alkyl barium intermediates cannot be observed and deprotonate the (Me Si) N ion, as confirmed by the crystal structure of Ba H [N(SiMe ) ] [(Me Si)(Me SiCH )N] .