On the formation of intermetalloid clusters: titanocene(III)diammin as a versatile reactant toward nonastannide Zintl clusters.

The reactivity of TiCp2Cl2 (d(0)) towards Zintl clusters was studied in liquid ammonia (Cp = cyclopentadienyl). Reduction of Ti(IV)Cp2Cl2 and ligand exchange led to the formation of [Ti(III)Cp2(NH3)2](+), also obtainable by recrystallization of [CpTi(III)Cl]2. Upon reaction with [K4Sn9], ligand exchange leads to [TiCp2(η(1)-Sn9)(NH3)](3-). A small variation of the stoichiometry led to the formation of [Ti(η(4)-Sn8)Cp](3-), which cocrystallizes with [TiCp2(NH3)2](+) and [TiCp2(η(1)-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(η(4+2)-Sn8)Cp](3-) has a key role.