language: en

DOI: 10.1002/zaac.200700461

Direct Syntheses of Bis(tetraphenylphosphonium) and Bis(ethyltriphenylphosphonium) Hexabromo-diselenates(II), [PPh 4 ] 2 [Se 2 Br 6 ] and [PEtPh 3 ] 2 [Se 2 Br 6 ]. The Crystal Structure of [PEtPh 3 ] 2 [Se 2 Br 6 ]

Vitalijus Janickis* , a , Max Herberhold b and Wolfgang Milius b
a Kaunas/Lithuania ,
Faculty of Chemical Technology, Kaunas University of Technology
b Bayreuth/Germany,
Laboratory of Inorganic Chemistry, University of Bayreuth

[Received September 21 st , 2007; accepted December 4 th , 2007.]

Abstract. Brown crystals of [PPh 4 ] 2 [Se 2 Br 6 ] (1) and [PEtPh 3 ] 2 [Se 2 Br 6 ] (2) were obtained when selenium and bromine reacted in acetonitrile solution in the presence of tetraphenylphosphonium bromide and ethyltriphenylphosphonium bromide, respectively. The crystal structure of 2 has been determined by Xray methods and refined to R 񮽙 0.0420 for 4161 reflections. The crystals are monoclinic, space group P2 1 /n with Z 񮽙 2 and a 񮽙 13.055(3) A b 񮽙 12.628(3) A c 񮽙 13.530(3) A β 񮽙 92.40(3)° (293(2) K). In the solid state structure of 2 the dinuclear hexabromo-diselenate(II) anion is centrosymmetric and consists of two distorted almost square-planar SeBr 4 units sharing a common edge through two bridging Br atoms. The terminal Se II 񮽙Br bond distances are found to be 2.419(1) and 2.445(1) A the bridging μBr񮽙Se II bond distances 2.901(1) and 2.802(1) A

Keywords: Selenium; Hexabromodiselenate(II); Crystal structure; Tetraphenylphosphonium and Ethyltriphenylphosphonium ions Introduction