Early-Lanthanide(III) Acetonitrile–Solvento Adducts with Iodide and Noncoordinating Anions

Dissolution of LnI3 (Ln = La, Ce) in acetonitrile (MeCN) results in the highly soluble solvates LnI3(MeCN)5 [Ln = La (1), Ce (2)] in good yield. The ionic complex [La­(MeCN)9]­[LaI6] (4), containing a rare homoleptic La3+ cation and anion, was also isolated as a minor product. Extending this chemistry to NdI3 results in the consistent formation of the complex ionic structure [Nd­(MeCN)9]2[NdI5(MeCN)]­[NdI6]­[I] (3), which contains an unprecedented pentaiodide lanthanoid anion. Also described is the synthesis, isolation, and structural characterization of several homoleptic early-lanthanide MeCN solvates with noncoordinating anions, namely, [Ln­(MeCN)9]­[AlCl4]3 [Ln = La (5), Ce (6), Nd (7)]. Notably, complex 6 is the first homoleptic cerium MeCN solvate reported to date. All reported complexes were structurally characterized by X-ray crystallography, as well as by IR spectroscopy and CHN elemental analysis. Complexes 1–3 were also characterized by thermogravimetric analysis coupled with mass spectrometry to further elucidate their bulk composition in the solid-state.