The kinetic and activation parameters of zinc oxidation with dicarbonylcyclopentadienyliron chloride in dimethylformamide were found. The apparent equilibrium constants, enthalpy, and entropy of the adsorption of the reagents on the metal surface were determined. A reaction scheme was suggested.
The kinetic and activation parameters of oxidation of cadmium with dicarbonylcyclopentadienyliron chloride in dimethylformamide were determined. The apparent equilibrium constants, enthalpy, and entropy of adsorption of the reactants on the metal surface were evaluated. The reaction scheme was suggested.In [1] we reported on the synthesis of an organometallic compound with a Mg3Fe bond by oxidation of Mg with dicarbonylcyclopentadienyliron chloride (I). In this study we examined the kinetics and products of the reaction of I with Cd.The dependences of the reaction rate on the content of I and dimethylformamide (DMF, used as solvent) in the reaction mixture are shown in Figs. 1 and 2. The curves shown in Figs. 1 and 2 do not allow unambiguous conclusion on whether the adsorption centers on the metal surface are similar or different in nature. Therefore, we studied the dependences of the reaction rate on the concentration of I at different fixed concentrations of DMF in the reaction mixture (Fig. 3). The results, in line with the concept presented in [2], suggest that both compound I and DMF are adsorbed on reaction centers of similar nature on the Cd surface. In this case, the reaction course can be described by the scheme Ox + S %%$ "%% OxS,The expression for the reaction rate is as follows:where k`= k(S 0 ) 2 , k is the rate constant, S 0 is the number of active centers on unit surface area of the metal, and K Ox ads and K L ads are the equilibrium constants of adsorption of the oxidant and ligand, respectively.Treatment of the experimental data in the coordinates (C Ox /V) 1/2 = f (C Ox ) at C L = const and (C L /V) 1/2 = f (C L ) at C Ox = const allowed calculation of the apparent equilibrium constants of adsorption of I and DMF and the reaction rate constants: T, K 278 288 293 K Ox ads 14.59 7.11 5.55 K L ads 0.25 0.19 0.16 k 10 2 , g cm !2 min !1 1.17 4.65 5.70From the temperature dependences of these quantities, we determined the apparent enthalpy and entropy of adsorption of the reactants on the metal surface: DH Ox ads 352 + 4 kJ mol !1 , DS Ox ads 3164 + 12 J mol !1 K !1 , DH L ads 321 + 2 kJ mol !1 , DS L ads 399 + 9 J mol !1 K !1 , and activation energy of the process E 75 + 5 kJ mol !1 .
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