Molecular building blocks for solid-state chalcogenides:: solvothermal synthesis of [Mn(en)3]Te4 and [Fe(en)3]2(Sb2Se5)

Two new molecular metal chalcogenides, tris(ethylenediamine-N,N')manganese(II) tetratelluride, [Mn(C2H8N2)(3)]Te-4, (I), and bis[tris(ethylenediamine-N,N')iron(II)] pentaselenodiantimonate(III), [Fe(C2H8N2)(3)](2)(Sb2Se5), (II), containing the isolated molecular building blocks Te-4(2-) and Sb2Se54- , have been synthesized by solvothermal reactions in an ethylenediamine solution at 433 K. The anion Te-4(2-) in (I) is a zigzag oligometric chain with Te-Te bond lengths in the range 2.709-2.751 Angstrom. There is a very short contact [3.329 (1) Angstrom] between a pair of neighboring Te-4(2-) anions. In (II), each Sb atom is surrounded by three Se atoms to give a tripodal coordination. One of the three independent Se atoms is a mu(2)-bridging ligand between two Sb atoms; the other two are terminal.