Publication details
Synthesis and Crystal Structure of Bis(tetraphenylphosphonium) Hexabromo-diselenate(II)-bis{dibromodiselenate(I)}, [PPh4]2[Se2Br6(Se2Br2)2], the Salt of a Mixed-valence Bromoselenate(II,I) Anion
| Authors | |
|---|---|
| Year of publication | 2008 |
| Type | Article in Periodical |
| Magazine / Source | Zeitschrift für Anorganische und Allgemeine Chemie |
| MU Faculty or unit | |
| Citation | |
| Web | http://dx.doi.org/10.1002/zaac.200700518 |
| Field | Inorganic chemistry |
| Keywords | Selenium; Bromoselenates(II-I); Mixed-valence Se(II)-Se(I) compounds; Crystal structure; Tetraphenylphosphonium ion |
| Description | The Red crystals of [PPh4]2[Se2Br6(Se2Br2)2] (1) were obtained when selenium and bromine reacted in the solution of acetonitrile in the presence of tetraphenylphosphonium bromide. The crystal structure of 1 has been determined by X-ray diffraction and refined to R = 0.0201 for 4024 reflections. The crystals are triclinic, space group P-1 with Z = 2 and a = 11.2757(4) A, b = 12.3347(5) A, c = 12.4948(5) A, = 113.152(4)deg, = 114.745(4)deg, = 91.208(3)deg (120(2) K). In the solid state the anion of 1 is built up of the Se2Br6 core and two Se2Br2 molecules each of which is linked to one of the trans-positioned terminal Brt atoms of the Se2Br6 core. The central Se2Br6 part consists of a nearly planar arrangement of two planar SeBr4 units sharing a common edge through two 2-bridging Br atoms. The contact between the Brt and the SeI atom of the Se2Br2 molecule is 3.0872(5) A and can be interpreted as a bond of the donor-acceptor type with the Brt as donor and the Se2Br2 molecule as acceptor. The terminal SeII-Br and 2Br-SeII bond lengths are 2.3654(4), 2.6699(5) A and 2.5482(5), 3.0265(5) A, respectively. The bond lengths in the coordinated Se2Br2 molecule are: SeI-SeI = 2.2686(5) A, SeI-Br = 2.3779(5) and 2.3810(5) A. |