Crystal structure analysis of the tetrameric 1:l adduct of PPh3 with CuBr, [CuBrPPhpl4, recrystallized from refluxing toluene, shows that it has crystallized in a 'cubane" rather than the previously recorded "step" form. A residual of 0.044 was obtained for 3708 independent observed diffractometer reflections recorded at 295 K after full-matrix least-squares refinement; crystals are isomorphous with the chloride, with an orthorhombic Pbcn cell, a = 17.662 ( 5 ) A, b = 20.748 (7) A, c = 18.351 (6) A, and Z(tetramer) = 4. The existence of the cubane form of the bromide was discovered during high-resolution solid-state 31P NMR spectral studies on a series of cuprous halide-triphenylphosphine complexes.