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Rhodo‐ und Erythro‐Salze des Chroms(III) Ionengewichte, Acidität und Basizität, Lichtabsorption und die Kinetik der Umwandlung
Author(s) -
Schwarzenbach G.,
Magyar B.
Publication year - 1962
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19620450508
Subject(s) - chemistry , deprotonation , substituent , medicinal chemistry , solvent , diastereomer , hydrolysis , protonation , ion , stereochemistry , organic chemistry
Cryoscopic measurements with n ‐Rhodochromium (III)‐sulfate and 4 different Erythrochromium (II)‐sulfates have been carried out, using the melt of Na 2 SO 4 , 10H 2 O as a solvent. The data prove that all the Rhodo and Erythro salts contain binuclear complexes of the general composition [(NH 3 ) 5 CrOHCr(NH 3 ) 4 X] v + , X = NH 3 , H 2 O, OH − , F − , Cl − , NCS − ( v = 5 + or 4 +). On adding a base, the bridging OH of the ions with X = NH 3 , F − , Cl − , NCS − can be deprotonated and the equilibria constants (pK‐values) of these reactions have been determined in a flow apparatus. The substituent X exerts an extraordinarily strong influence on the acidity of the bridging OH. The absorption spectra of the unstable deprotonated complexes (μ‐Oxocomplexes) have also been taken in the flow apparatus and are compared with the spectra of the corresponding μ‐Hydroxo complexes. The deprotonated species undergo rapid hydrolysis; the nature of these reactions has been elucidated and their rates have been determined.