Tetra­kis(1,2-dimethoxy­ethane-κ(2) O,O′)ytterbium(II) bis­(μ(2)-phenyl­selenolato-κ(2) Se:Se)bis­[bis­(phenyl­selenolato-κSe)mercurate(II)]

The title salt, [Yb(C(4)H(10)O(2))(4)][Hg(2)(C(6)H(5)Se)(6)], consists of eight-coordinate homoleptic [Yb(DME)(4)](2+) dications (DME is 1,2-dimethoxy­ethane) countered with [Hg(2)(SePh)(6)](2−) di­anions. The cations and anions have twofold rotation and inversion symmetry, respectively. The Yb centre displays a square-anti­prismatic coordination geometry and the Hg centre has a distorted tetra­hedral coordination environment. One phenyl­selenolate anion and one methyl group of a DME ligand are disordered over two positions with equal occupancies. This structure is unique in that it represents a less common mol­ecular lanthanide species in which the lanthanide ion is not directly bonded to an anionic ligand. There are no occurrences of the [Hg(2)(SePh)(6)](2−) dianion in the Cambridge Structural Database (Version of November 2007), but there are similar oligomeric and polymeric Hg(x)(SePh)(y) species. The crystal structure is characterized by alternating layers of cations and anions stacked along the c axis.