The First Example of the Tetraselenidostannate Anion [SnSe4]4- as a Chelating Ligand to a Lanthanide Complex Ion: Solvothermal Synthesis and Characterization of Lanthanoid Selenidostannates [Hdien][Ln(dien)2(μ-SnSe4)] (Ln = Sm, Eu) and [Eu2(dien)4(μ-OH)2]Sn2Se6

New lanthanoid selenidostannates [Hdien][Ln(dien)(2)(mu-SnSe4)] [Ln = Sm (1), Eu (2); then = diethylenetriamine] were solvothermally prepared by reaction of Ln(2)O(3) (Ln = Sm, Eu) with Sn and Se in dien. The structures of 1 and 2 consist of the tetraselenidostannate anion [SnSe4](4-) coordinating to a [Ln(dien)(2)](3+) fragment as a bidentate chelating ligand. The reaction of Ln(2)O(3) and Se with SnCl4 center dot 5H(2)O under the same solvothermal conditions produces the selenidostannate [Eu-2(dien)(4)(mu-OH)(2)]Sn2Se6 (3), which is constructed from the two dinuclear ions [Eu-2(dien)(4)(mu-OH)(2)](4+) and [Sn2Se6](4-). The water molecule prevents the [SnSe4](4-) anion from coordinating to the lanthanide center. As far as we know, compounds 1 and 2 are the first selenidostannates integrated within lanthanoid complexes prepared under mild solvothermal conditions. Upon heating, compounds 1 and 2 decompose in three steps, whereas compound 3 undergoes a one-step decomposition procedure. The band gaps of 2.52, 2.08, and 2.43 eV were derived from optical absorption spectra for compounds 1, 2, and 3, respectively. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)