Novel one-, two-, and three-dimensional selenidostannates templated by iron(II) complex cation

The novel iron selenidostannates [Fe(bipy)₃]Sn₄Se₉·2H₂O (1) and [Fe(bipy)₃]₂[Sn₃Se₇]₂·bipy·2H₂O (2) (bipy = bipyridine) were prepared by the reactions of Sn, Se, FeCl₂·4H₂O, bipy, and dien with/without KSCN under hydrothermal conditions (dien = diethylenetriamine). In 1, four SnSe₅ units condense via edge sharing to form the novel 3-D framework selenidostannate (∞)³[Sn₄Se₉²⁻] containing an interpenetrating channel system. The [Fe(bipy)₃]²⁺ cations are accommodated in the different channels according to the conformation of the [Fe(bipy)₃]²⁺ cation. In 2, three SnSe₅ units share edges to form a 2-D (∞)²[Sn₃Se₇²⁻] layered anion, while two SnSe₅ units and one SnSe₄ unit are connected via edge sharing, forming a 1-D (∞)¹[Sn₃Se₇²⁻] chainlike anion. The (∞)¹[Sn₃Se₇²⁻], [Fe(bipy)₃]²⁺, bipy, and H₂O species are embedded between the (∞)²[Sn₃Se₇²⁻] layers. 2 is the first example of a selenidostannate constructed by both (∞)²[Sn₃Se₇²⁻]and (∞)¹[Sn₃Se₇²⁻] anions. The coexistence of 1-D (∞)¹[Sn₃Se₇²⁻] and 2-D (∞)²[Sn₃Se₇²⁻] anions in 2 might support the possible reaction mechanism that the (∞)²[Sn₃Se₇²⁻] anions are formed by condensation of the (∞)¹[Sn₃Se₇²⁻] chains. 1 and 2 exhibit band gaps at 1.43 and 2.01 eV, respectively.