62350-87-2Relevant articles and documents
Structural isomerism in (p-XC6H4)SeCl3 and (p-XC6H4)SeBr3 (X = F, Cl) compounds. Co-crystallisation of cis- and trans-dimeric forms of (p-ClC6H 4)SeCl2(μ-Cl)2(p-ClC6H4)SeCl2. A new structural modification for the "phSeBr" reagent, Ph2Se2Br2, containing an elongated Se-Se bond
Barnes, Nicholas A.,Godfrey, Stephen M.,Ollerenshaw, Ruth T. A.,Khan, Rana Z.,Pritchard, Robin G.
, p. 14583 - 14593 (2013/01/16)
A series of di(para-halophenyl)diselenides, (p-XC6H 4)2Se2 (X = F, Cl) have been reacted with three equivalents of SO2Cl2 or Br2, leading to the formation of selenium(iv) RSeX3 compounds. The structures of (p-FC6H4)SeX3 (X = Cl, Br) have been determined, and both exhibit a dimeric RSeX2(μ-X) 2RSeX2 structure consisting of two "saw-horse" (p-FC6H4)SeX3 units linked by two halide bridges, with an overall square pyramidal geometry at selenium. In both structures all the selenium and halogen atoms are planar, with both aryl rings located on the same side of the Se2X6 plane (cis-isomer). The structure of (p-ClC6H4)SeCl3 also adopts a planar dimeric structure, however both cis- and trans-dimeric molecules are co-crystallised in the unit cell. In contrast, the structure of (p-ClC 6H4)SeBr3 adopts a folded cis-dimeric structure due to steric constraints. Secondary Se...X interactions to the "vacant" sixth coordination site at selenium are a feature of most of these structures, but are most prominent in the folded structure of (p-ClC 6H4)SeBr3. A re-examination of the PhSeBr/PhSeBr3 system resulted in the isolation of crystals of a second structural form of "PhSeBr". The structure of Ph 2Se2Br2 consists of two PhSeBr units linked by an elongated Se-Se bond of 2.832(4) A, and longer secondary Se...Br interactions of 3.333(4) A to form a chain structure. Further weak Se...Br and Br...Br interactions are present, which form loosely linked rippled sheets of selenium and bromine atoms, similar to the sheets observed for the tetrameric form, Ph4Se4Br4.
