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The stepwise formation constants for the chloride complexes of palladium(II) have been determined from spectrophotometric measurements made at 21, 29.5 and 38°. The reaction between palladium(II) chloride and acetylacetone in aqueous solution has also been investigated, but from pH measurements at 20, 30 and 40°. The logarithm of the over-all formation constant for PdCU-2, estimated to be 15.8 at 25°, is observed to be of the same order of magnitude as that for PtCU-2 and HgCl,-2. The thermodynamic stability of bis-(acetylacetonato)-palladium(II) is greater than would be anticipated from considerations of the electronegativity and the second ionization potential of palladium.

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The value of An at 27°is a measure of the amount of decomposition product still gaseous at room temperature. The fact that An at 27°is still large, in many cases, indicates that at least some of the decomposition products are of low molecular weight. The nature of the volatile decomposition products for certain of these compounds is currently being investigated. The results of this study will be reported in a later paper.The nature of the solid residues obtained from the decomposition of the acetylacetonates was not determined. In general the change in appearance of the chelates paralleled the extent of decomposition, as indicated by An. Those acetylacetonates undergoing extensive decomposition generally gave very dark colored, and frequently resinous, residues. It is planned to study the nature of some of these materials.Acknowledgment.-The authors are grateful to Miss . I. Mistrik for certain of the analyses.