An unprecedented mu4-Sn2Se9 ligand: solvothermal syntheses and characterizations of novel lanthanum selenidostannates [{La(dien)2}4(mu4-Sn2Se9)(mu-Sn2Se6)]infinity and [La2(en)8(mu-Se2)]Sn2Se6.

Solvothermal reaction of La2O3, Sn and Se in dien yields a novel lanthanide selenidostannate [{La(dien)2}4(mu4-Sn2Se9)(mu-Sn2Se6)]infinity, the first example of the coordination of Sn2Se9 and Sn2Se6 ligands to hard Lewis acidic lanthanide metals, while the reaction in en yields an ionic compound [La2(en)8(mu-Se2)]Sn2Se6 containing a ten-coordinated binuclear lanthanum complex [La2(en)8(Se2)]4+ with the diselenide Se(2)(2-) group as a bridging ligand.