Acknowledgments.-The authors are indebted to Prof. Charles V. Banks and the Analytical Service Group of the ,knes Laboratory for spectrophotometric determinations in conjunction with the
[CONTRIBUTIOS FROM
THE
dielectric constant measurements arid to lliller Layton for his assistance in obtaining the Iiaman spectra. AVW, IO\{
A
DEPARTMENT O F CHEMISTRY O F
THE
UNIVERSITY O F KANSAS]
Some Observations on Lower Halides of Indium BE' RONALDJ.
CLARK,
ERNEST GRISWOLD AND
JACOB
KLEINBERG
RECEIVEDXPRIL 12, 1958 Iridium nionohalides and dihalides have been prepared conveniently b y reaction of t h e metal with appropriate quantities A phase study of the system InC1-InCI3 has demonstrated t h e unlikelihood of the existence of InCI?; t h e most stable species found in the system has a composition In2C13and is reasonably formulated a s In,1 [ I ~ I I I C I G ]The . compound InJAICI,] has been prepared and characterized. o f mercury(1) or mercury(I1) halides.
Recent work'-:' has provided strong evidence that in gallium dichloride two oxidation states of galliuin are exhibited and t h a t the compound is best formulated as GaI[GaIIIC14]. The present investigation was undertaken t o obtain information which might shed light on the oxidation state(s) i n the substance reported t o have the composition ItlCl2. I n the course of this work, it wxs found t h a t the method developd in this Laboratory for the preparation of gallium dihalides. namely, reaction OC the metal with niercury(1) or mercury(I1) halide, was applicable to the synthesis of both indium monohalides and dihalides. lloreover. a similar reaction carried out in the presence of eleniental aluminum yielded the indiumiI) compound In [AlCI,J. In view of conflicting reports in the literature on the melting behavior of InCl?, a phase study of the system InC1--InCLI was uticlertaken. The results of this study showed that it is highly doubtful t h a t InCl:, exists as a definite compound.
dide, for the synthesis of lower bromides and iodides, were of reagent grade, meeting h C S specifications. T h e re action vessel used in all preparations consisted of a 20 X 0.8 mi. thick-walled Pyrex tube with a one cm. well located xbout 6 cm. from the closed end of the tube. Throughout the work described in this paper, transfers of moisture- or oxygen-sensitive materials were carried out in a dry box under nitrogen. Essentially stoichiometric proportions of mercury halide and indium metal were employed in all preparations, except t h a t of the monochloride. iVhen the theoretical quantities of indium and mercury(1) chloride were taken, a product of the composition 1nC11,,~ mas obtained. large excess of the metal was necessary in order that a product approximating InCl in coniposition be formed. T h e preparative procedure described below for indium monoiodide may be regarded as typical. T o t h e reaction tube, 1.2214 g. (0.00269 mole) of mercury(I1) iodide and 0.6266 g. (0.00546 mole) of indium metal were added. The tube was then evacuated t o a pressure of 10-1.5 p and sealed. Reaction was effected b y heating t o about -100" in a muffle furnace for about 30 min., after which the tube wastilted t o allow the mercury formed in the reaction t o collect in the well. T o ensure complete removal of mercury, the end of the tube containing the indium product was heated a t about 350" for 2 hr. in a tube furnace, while the portion t o which the well was attached was maintained at room temperature. Preparation of Lower Halides of Indium.-Methods preReaction temperatures for the preparation of the other viously reported for t h e preparation of the dihalides include halides were as follows: monochloride, 325' ; tnonobromide, reducticin of trihalides v-it11 indium rnetal,j,6 reaction of irietnl witli lij-drcigen halide,' direct union of the elements*,g :?
