Tetraphenyldibismuth, Bi2Ph4, is best prepared by the reaction of BiPh2I with 1 equivalent of sodium in liquid ammonia, followed by extraction with toluene and recrystallization from anhydrous ethanol. It is sensitive to air and slightly thermochromic. The crystal and molecular structure was solved by X-ray diffraction methods: triclinic, space group P, with a= 7.865(4), b= 11.444(5), c= 6.257(3)Å, α= 105.24(4), β= 94.20(7), γ= 96.52(6)°, and Z= 1; R= 0.0560 for 1 097 absorption-corrected reflections having I 3σ(I). The molecule has a staggered trans conformation, with a bismuth–bismuth distance of 2.990(2)Å. Tetraphenyldibismuth reacts promptly with di-iodine to give BiPh2I, and with p-benzoquinone, elemental sulphur, and diazomethane to give the corresponding products of bismuth(III) resulting from oxidative insertion into the bismuth–bismuth bond.