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Crystalline dicyanide-dihalide complexes of gold(II1) (KXU(CX)~XZ, where X = C1, Br, or I) are formed on treatment of KAu( CN)Z with the free halogens coordinated halide in aqueous Au( CN)aXZ-is completely replaced by two equivalents of CN-; the reverse reaction does not occur in saturated halide solution. The highest cyanide complex of gold observed by means of infrared spectra in saturated KCN solution was AU(CN)~-. Chlorine treatment of K A u ( C N )~ and KBr in methanol yielded Khu(CN)3Cl. Oxidation of Ag(CN)S-with Brz does not yield a complex of Ag(II1) but AgBr and BrCN; iodine and chlorine react similarly. The infrared absorption spectra of Au( CN)zCl~-, Au( CN)zBrz-, Au( CN)zIz-, Au-(CN)aCl-, and HAu( CN)a,2HzO and the Raman spectra of Au( CN)zCI-and HAu( CN)4.2Hz0 were recorded. The spectrum of the solid acid, HAu(CN)4.2HzO, shows that the acidic hydrogen is hydrated to form H30+. The Raman and infrared spectra of Au(CN)3CI-suggest the planar configuration of CZ, symmetry.

Raman spectra of Hg(I1) in aqueous NaCN-Sa1 show peaks unique to the mixtures a t 2157,2180-2200, and 318-330 cm-l. The first of these is assigned t o Hg(CN)JZ-on the basis of observed trends with solution composition. The last two show variations in position with NaI concentration and have been assigned to the general composition Hg(CN)21,Z-. Raman spectra of Hg(CN)JZZ-solutions show remarkable similarity to the spectrum of solid K I . Hg(CN)% in which essentially linear Hg(CN)Z groups are coordinated by equatorial iodides Study of the disappearance of the 3225-A peak of H g L -, when 5 X NaI solutions dilute in Hg(1I) are made several millimolar in NaCN, indicates formation of Hg(CN)112-and H g ( C N ) & -. One additional mixed-ligand complex, namely, Hg(CX)I, is fo:med from Hg(CN)% and HgI2 with a formation constant of 0.14. This n e x complex exhibits a n ultraviolet peak a t 2370 A. IntroductionMercuric ion is a class B ion and forms strong complexes with both cyanide and iodide. The stepwise formation constants for the mono and di ligand complexes are about five orders of magnitude greater for cyanide than for iodide; the stepwise constants for the tri-and tetraligand complexes, in contrast, are of the same order of magnitude.? This paper reports a study of a number of the mixed-ligand complexes using Raman and ultraviolet spectrometry.