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

Reaction of Ba[N(SiMe3)2]2 with PhSiH3 in toluene gave simple access to the unique Ba hydride cluster Ba7H7[N(SiMe3)2]7 that can be described as a square pyramide spanned by five Ba2+ ions with two flanking BaH[N(SiMe3)2] units. This heptanuclear cluster is well soluble in aromatic solvents and the hydride 1H 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 Ba hydride species. Complex Ba7H7[N(SiMe3)2]7 is a very strong reducing agent that already at room temperature reacts with Me3SiCH=CH2, norbornadiene and ethylene. The highly reactive alkylbarium intermediates cannot be observed and deprotonate the (Me3Si)2Nˉ ion, as confirmed by the crystal structure of Ba14H12[N(SiMe3)2]12[(Me3Si)(Me2SiCH2)N]4.