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The classical Debye-Hückel theory of strong electrolyte solutions was re-examined in order to explain ion association. Regarding a symmetrical electrolyte in very dilute solutions, a more precise expression was derived for excess chemical potential due to electrostatic ion-ion interactions. This expression has, in addition to the Debye-Hückel term, a supplementary term resulting from a more proper account of the energy of the interactions of ions existing near each other. If the concept of ion association is taken as a complement of the Debye-Hückel theory, the contribution to the chemical potential of the electrolyte from ion association should correspond to the supplementary term. The following equation was thus obtained for the ion-association constant: K=(8πNa^3/1000) \overset∞\undersetn=1∑b^2n+2/[(2n+2)! (2n-1)] This equation is in agreement with that derived by Ebeling on the basis of the cluster theory and has an asymptotic representation (at b→∞) in common with Bjerrum’s. For practical b values, the present equation has the merit that it gives moderate K values, decreasing monotonously with an increase in the a value, and eliminates the disadvantages of Fuoss’s result, giving a minimum K value at b=3, and of Bjerrum’s, giving K=0 at ≤2.

52system. For DsL << DCuKTSM2 the lower limit for the translational diffusion coefficient for CuKTSM2 is equal to (60 -95) X lo-* cm2/s. Because the translational diffusion constant for 16-SASL at that temperature in DMPC is about 5 X the assumption that DsL Abstract: Nickel species contained in Y-type zeolite have been characterized by an EXAFS technique at each stage of catalyst preparation. When nickel ions were incorporated into the zeolite by aqueous ion exchange, a kind of "solution-like" hydrated state with Ni-O = 2.06 8, was suggested from the EXAFS analysis. After calcination, the nickel ions, surrounded by an average of 3.6 oxygen atoms with Ni-0 = 2.05 8,, scattered around the exchangeable sites with unsaturated coordination. According to the EXAFS and ESCA (electron spectroscopy for chemical analysis) results, the nickel ions in this state could not be reduced completely by hydrogen. On the contrary, a different behavior of hydrogen reduction was observed after treatment of the hydrated-nickel zeolite with an aqueous sodium hydroxide solution. A new nickel hydroxide oligomer with Ni-0 = 2.06 8, was formed in the supercage by this treatment. Moreover, calcination of this alkali-treated zeolite under oxygen atmosphere gave another new product containing nickel atoms with 3.5 oxygen neighbors at 2.08 8, and three second-nearest nickel neighbors at 2.99 8,. These oligomeric nickel-oxide clusters are certainly responsible for the high catalytic activity in CO oxidation. Hydrogen reduction of the small oxide clusters gave the zeolite catalyst which has an excellent activity for benzene hydrogenation. This material was confirmed to contain finely dispersed metallic nickel by the radial distribution function derived from the EXAFS spectrum.Zeolites are crystalline aluminosilicates consisting of threedimensional arrays of SiO, and AIO, tetrahedra. The void space enclosed within the unit is called the sodalite cage,! whereas a larger void space, called the supercage, is formed by linking sodalite units by hexagonal prisms. Windows 7.4 A in diameter (8) Morrison, T. I.; Iton, L. E.; Shenoy, G. K.; Stucky, G. D.; Suib, S. L.

Rare earth (RE) halides (fluorides, chlorides, bromides, and iodides) have been studied by X-ray photoelectron spectroscopy. The binding energies (BE’s) of the RE 3d and 4d peaks for the chlorides, bromides, and iodides are related to the atomic charge calculated on the basis of Pauling’s scale of electronegativity (Pauling charge). Except for Y and Lu, the observed RE 3d and 4d BE’s for the fluorides are lower than those expected. For Y and Lu, the observed RE 3d and 4d BE’s for all halides are related to the Pauling charge. For the fluorides and chlorides, the BE’s of the ligand peak show variations with increasing atomic number of RE’s and a specific “tetrad effect” is observed in plots of BE versus RE atomic number and versus 1/R (where R is the mean distance from the ligand atom to the neighboring RE atom), except for the BE’s of the F 1s peaks from the light RE fluorides. For the iodides and bromides, no or little characteristic variations are seen in the BE’s of I and Br.

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The core binding energies of N1s and S2s in cis-1,2-dicyano-1,2-ethanedithiolate (maleonitriledithiolate, mnt) complexes were measured by means of X-ray photoelectron spectroscopy (XPS), and the energy differences between N1s and S2s, ΔE, were found to be 171.7–172.6 eV throughout the complexes studied. The lowest ΔE value, 171.7 eV, was shown by [Ni(mnt)2]−. The electronic structures of [Ni(mnt)2]− and [Ni(mnt)2]2− were calculated by the discrete variational Xα method. The XPS measurements and the molecular orbital (MO) calculations provide consistent results that the oxidation state of the nickel atom is +2 for both nickel mnt complexes and that the highest occupied MO is 5b3g, which is mainly localized on ligands and which holds an unpaired electron in [Ni(mnt)2]−.

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