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Kinetics of the substitution reactions of chromium(III) complexes. III. The solvation of the trans-dithiocyanatobis(ethyl-enediamine)chromium(III) ion

V. Holba

Komensk√Ĺ University, Bratislava


Abstract:  Kinetics of the solvation of trans-[Cr(SCN)2-(en)2]+ ion in 0.01M HNO3 at 50° was studied by a spectro-photometric method. From the change of the absorption spectra at 520 mμ in relation to time (0-150 min.) and from the change of pH from 2.0 to 2.41, it was detd. that the solvation occurs in 2 steps. The reaction scheme may be expressed as: [Cr-(SCN)2(en)2]+ + 2H2O k1 → [Cr(SCN)2(H2O)2en]+ + en (1) and [Cr(SCN)2(H2O)2en]+ + H2O k2 → [CrSCN(H2O)3en]2+ + SCN-(2), where k1 > k2. In reaction 1 there is a substitution of the ethylenediamine with H2O, which is liberated. The velocity const. is k1 = 5.3 × 10-3/min. The activation energy is EA = 24.4 kcal./mol. In reaction 2, SCN- is liberated and the velocity const. is k2 = 2.4 × 10-4/min.

Full paper in Portable Document Format: 196a441.pdf (in Slovak)


Chemical Papers 19 (6) 441–446 (1965)

Monday, June 17, 2024

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