On the Formation of Intermetalloid Clusters: Titanocene(III)diammin as a Versatile Reactant Toward Nonastannide Zintl Clusters

The reactivity of TiCp₂Cl₂ (d⁰) towards Zintl clusters was studied in liquid ammonia (Cp=cyclopentadienyl). Reduction of Ti^IVCp₂Cl₂ and ligand exchange led to the formation of [Ti^IIICp₂(NH₃)₂]⁺, also obtainable by recrystallization of [CpTi^IIICl]₂. Upon reaction with [K₄Sn₉], ligand exchange leads to [TiCp₂(η¹‐Sn₉)(NH₃)]^3?. A small variation of the stoichiometry led to the formation of [Ti(η⁴‐Sn₈)Cp]^3?, which cocrystallizes with [TiCp₂(NH₃)₂]⁺ and [TiCp₂(η¹‐Sn₉)(NH₃)]^3?. Finally, the large intermetalloid cluster anion [Ti₄Sn₁₅Cp₅]^n? (n=4 or 5) was obtained from the reaction of K₁₂Sn₁₇ and TiCp₂Cl₂ in liquid ammonia. The isolation of three side products, [K([18]crown‐6)]Cp, [K([18]crown‐6)]Cp(NH₃), and [K([2.2]crypt)]Cp, suggests a stepwise elimination of the Cl^? and Cp^? ligands from TiCp₂Cl₂ and thus gives a hint to the mechanism of the product formation in which [Ti(η⁴⁺²‐Sn₈)Cp]^3? has a key role.