Trapping an Unexpected/Unprecedented Hexanuclear Ce(III) Hydrolysis Product with Neutral 4‐Amino‐1,2,4‐triazole
Using Ce(III) as both a representative lanthanide and actinide analog, the ability of mixtures of acidic and basic azoles to allow direct access to homoleptic N-donor f-element complexes in one pot reactions from hydrated salts as starting materials was examined by reacting mixtures of 4-amino-1,2,4-triazole (4-NH 2 -1,2,4-Triaz), 5-amino-tetrazole (5-NH 2 -HTetaz), and 1,2,3-triazole (1,2,3-HTriaz) in 1 : 1 and 1 : 3 ratios with CeCl 3 ⋅ 7H 2 O, [C 2 mim] 3 [CeCl 6 ] ([C 2 mim] + =1-ethyl-2-methylimidazolium), and Ce(NO 3 ) 3 ⋅ 6H 2 O. Although unsuccessful in our goal, structural analysis revealed that neutral 4-NH 2 -1,2,4-Triaz is structure directing via η 2 μ 2 κ 2 bridging, with the formation of the dinuclear complexes [Ce 2 Cl 2 (μ 2 -4-NH 2 -1,2,4-Triaz) 4 (H 2 O) 8 ]Cl 4 ⋅ 4H 2 O, [Ce 2 (μ 2 -4-NH 2 -1,2,4-Triaz) 4 (4-NH 2 -1,2,4-Triaz) 2 (Cl) 6 ], and [4-NH 2 -1,2,4-HTriaz][Ce 2 (μ 2 -4-NH 2 -1,2,4-Triaz) 2 (μ 2 -NO 3 )(NO 3 ) 6 (H 2 O) 2 ]. When the synthetic conditions favored hydrolysis, the hexanuclear Ce(III) complex [Ce 6 (μ 3 -O) 4 (μ 3 -OH) 2 (μ 3 -Cl) 2 (Cl) 6 (μ 2 -4-NH 2 -1,2,4-Triaz) 12 ] ⋅ 7H 2 O was isolated. This unexpected hydrolysis product represents the first example of a high nuclearity lanthanide complex where all Ln atoms are pairwise connected through 12 N-donor ligands or 12 neutral bridging ligands of any type, a rare example of incorporation of non-oxo coordinating anions in the M 6 X 8 core, and the first reported Ce(III) hexanuclear complex of this type.