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

Abstract

Reaction of Ba[N(SiMe₃ )₂ ]₂ with PhSiH₃ in toluene gave simple access to the unique Ba hydride cluster Ba₇ H₇ [N(SiMe₃ )₂ ]₇ that can be described as a square pyramid 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 ¹ 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 Ba₇ H₇ [N(SiMe₃ )₂ ]₇ is a very strong reducing agent that already at room temperature reacts with Me₃ SiCH=CH₂ , norbornadiene, and ethylene. The highly reactive alkyl barium intermediates cannot be observed and deprotonate the (Me₃ Si)₂ N^- ion, as confirmed by the crystal structure of Ba₁₄ H₁₂ [N(SiMe₃ )₂ ]₁₂ [(Me₃ Si)(Me₂ SiCH₂ )N]₄ .