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.