Tris(4-bromophenyl)ammoniumyl hexachloroantimonate is the organic compound with the formula [(4-BrC<sub>6</sub>H<sub>4</sub>)<sub>3</sub>N]SbCl<sub>6</sub>. Commonly known as magic blue, it is the hexachloroantimonate salt of an amine radical cation. It is a blue solid that reacts with many solvents but is soluble in acetonitrile. The compound is a popular oxidizing agent in organic and organometallic chemistry, with a reduction potential of 0.67 V versus ferrocene/ferrocenium (acetonitrile solution) or 0.70 V versus ferrocene/ferrocenium (dichloromethane solution).
The structure of the cation consists of a three-bladed propeller structure with a planar amine. It is nearly identical to the parent triphenylamine. The weakly coordinating anion is , which is octahedral.