The preparation, magnetic susceptibility, ultraviolet, infrared, and electron spin resonance spectra, electric conductivity, and X-ray diffraction of a series of compounds bis(N,N-di-#-butyldithiocarbamato)gold(III) dihaloaurate(I) of formula [Au(S2CN(re-C4H9)2)2] [AuX2], where X is Cl, Br, I, or CN, are reported. The chlorine, bromine, and iodine compounds are isomorphous and crystallize in the monoclinic space group C2/c. The crystal structure of the bromine compound has been determined by a three-dimensional X-ray analysis. The unit cell dimensions measured from photographs taken at -150°a re: a = 22.38 ± 0.03, b = 15.80 ± 0.03, c = 8.11 ± 0.04 Á, ß = 98.2 ± 0.3°, Z = 4. The measured and calculated densities are Dm = 2.18 ± 0.01 and Dx = 2.18 ± 0.01 g cm-3. About 1100 intensities were measured photometrically from equiinclination Weissenberg photographs taken at -150°. The structural parameters were refined by least-squares methods to a conventional R factor of 0.11. Although the stoichiometry of these compounds is appropriate for an oxidation state of 2, the diamagnetism and the dissociation as 1:1 electrolytes in nitrobenzene prove them to contain equivalent amounts o f Au(I) and Au(III) in AuX2~and [Au(S2CN(re-C4Hg)2)2], respectively. The Au(I) is linearly coordinated by two X in the AuX2~ion. The Au(I)-Br distance is 2.349 ± 0.005 Á. The Au(III) is in planar coordination with four S atoms in the [Au(S2CN(C4Hg)2)2] + ion. The two nonequivalent Au-S distances are 2.332 ± 0.009 and 2.333 ± 0.009 Á. Infrared data concerning C-N and Au-X stretching frequencies are in accord with the proposed structure.The halogen-gold stretching frequencies depend upon the nature of the ligand trans to the halogen and are little influenced by the oxidation state and the coordination symmetry of the gold.