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

Dissolution of LnI(3) (Ln = La, Ce) in acetonitrile (MeCN) results in the highly soluble solvates LnI(3)(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.