Varied forms of lamellar [Sn3Se7]n2n− anion: the competitive and synergistic structure-directing effects of metal–amine complex and imidazolium cations. Issue 16 (23rd March 2015) - Du, Cheng-Feng
Abstract : Presented are the varied forms of a lamellar [Sn3 Se7 ] n 2 n − anion produced by the competitive and synergistic structure-directing effects of a metal–amine complex and imidazolium cations. Abstract : Presented are the syntheses, characterizations and properties of a series of selenidostannate compounds directed by metal–amine complex (MAC) cations and/or [Bmmim] + (Bmmim = 1-butyl-2, 3-dimethylimidazolium). Mixtures of the ionic liquid (IL) (Bmmim)Cl and amines, such as ethylenediamine (en) and diethylenetriamine (dien), in various ratios were used to ionothermally/solvothermally prepare four selenidostannates, namely, [Mn(en)3 ]Sn3 Se7 (1 ), [Mn(dien)2 ]Sn3 Se7 ·H2 O (2 ), (Bmmim)3 [Mn(en)3 ]2 [Sn9 Se21 ]Cl (3 ) and (Bmmim)6 [Mn(dien)2 ]2 Sn15 Se35 (4 ). Single-crystal X-ray diffraction analyses revealed that these compounds exhibit lamellar anionic [Sn3 Se7 ] n 2 n − structures. [Sn3 Se7 ] n 2 n − layers in all1–4 possess a {6 3 } net, considering [Sn3 Se10 ] semi-cube unit as a 3-connected node; however, diverse multi-membered rings exist there. In compounds1 and2, all the [Sn3 Se10 ] units are 3-connected nodes interlinking with each other via edge-sharing two Se atoms to produce six-membered rings. However, in compound3, the insertion of two [Sn3 Se9 ] units into a six-membered ring results in a novel eight-membered heart-shaped ring, which has never been observed before in the family of chalcogenidostannates. More interestingly, the [Sn3 Se7 ] n 2 n − layer in compound4 consists of mixed six- and eight-membered rings. The phase composition is strongly dependent on the ratio of IL to MAC in the syntheses, e.g., 1 and2 were obtained with IL : MAC ratios less than 3 : 1 and 4 : 1, while3 and4 were obtained when the ratios were increased to 4 : 1 and 5 : 1, respectively. The structural variation from1 to4 clearly indicates the competitive and synergistic effects between MAC and IL cation on the formation of lamellar selenidostannates. A synthetic approach via varying the ratio of IL to MAC cation as solvent and structure-directing agent will be attractive in the synthesis of novel chalcogenidometallates.