Cube-Type Nitrido Complexes Containing Titanium and Alkali/Alkaline-Earth Metals

Treatment of [{Ti(η5-C5Me5)(μ-NH)}3(μ3-N)] with alkali-metal bis(trimethylsilyl)amido derivatives [M{N(SiMe3)2}] in
toluene affords edge-linked double-cube nitrido complexes [M(μ4-N)(μ3-NH)2{Ti3(η5-C5Me5)3(μ3-N)}]2 (M = Li, Na,
K, Rb, Cs) or corner-shared double-cube nitrido complexes [M(μ3-N)(μ3-NH)5{Ti3(η5-C5Me5)3(μ3-N)}2] (M = Na, K,
Rb, Cs). Analogous reactions with 1/2 equiv of alkaline-earth bis(trimethylsilyl)amido derivatives [M{N(SiMe3)2}2(thf)2] give corner-shared double-cube nitrido complexes [M{(μ3-N)(μ3-NH)2Ti3(η5-C5Me5)3(μ3-N)}2] (M = Mg, Ca,
Sr, Ba). If 1 equiv of the group 2 amido reagent is employed, single-cube-type derivatives [(thf)x{(Me3Si)2N}M{(μ3-N)(μ3-NH)2Ti3(η5-C5Me5)3(μ3-N)}] (M = Mg, x = 0; M = Ca, Sr, Ba, x = 1) can be isolated or identified. The
tetrahydrofuran molecules are easily displaced with 4-tert-butylpyridine in toluene, affording the analogous complexes
[(tBupy){(Me3Si)2N}M{(μ3-N)(μ3-NH)2Ti3(η5-C5Me5)3(μ3-N)}] (M = Ca, Sr). The X-ray crystal structures of [M(μ3-N)(μ3-NH)5{Ti3(η5-C5Me5)3(μ3-N)}2] (M = K, Rb, Cs) and [M{(μ3-N)(μ3-NH)2Ti3(η5-C5Me5)3(μ3-N)}2] (M = Ca, Sr)
have been determined. The properties and solid-state structures of the azaheterometallocubane complexes bearing
alkali and alkaline-earth metals are discussed.