Construction of Ternary Iodine-Bromine-Chlorine Octahalides.

A series of five ternary octanuclear iodine-bromine-chlorine interhalides, [I2 Br2 Cl4 ]2- (1), [I3 BrCl4 ]2- (2), [I4 Br2 Cl2 ]2- (3), [I2 Br4 Cl2 ]2- (4) and [I3 Br3 Cl2 ]2- (5), have been rationally constructed in two steps. Firstly, addition of a dihalogen (ICl or IBr) to the triaminocyclopropenium chloride salt [C3 (NEt2 )3 ]Cl forms the corresponding trihalide salt with [ICl2 ]- or [BrICl]- anions, respectively. Secondly, addition of a half-equivalent of a second dihalogen, followed by crystallization at low temperature, gives the corresponding octahalide: addition of Br2 and IBr to [ICl2 ]- gives 1 and 2, respectively, whereas addition of I2 , Br2 and IBr to [BrICl]- gives 3, 4 and 5, respectively. The five octahalides were characterized by X-ray crystallography and far-IR spectroscopy.