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Kobalt(III)‐Komplexe von N, N, N′, N′‐Tetrakis‐(β‐aminoäthyl)‐äthylendiamin (= «penten»)
Author(s) -
Emmenegger F. P.,
Schwarzenbach G.
Publication year - 1966
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.19660490102
Subject(s) - chemistry , ring (chemistry) , racemization , medicinal chemistry , ligand (biochemistry) , stereochemistry , chelation , crystallography , inorganic chemistry , organic chemistry , biochemistry , receptor
Abstract Several salts containing the cation Co(penten) 3+ , in which the hexamin «penten» (formula: page 625) acts as a sexadentate ligand, have been synthesized and characterized. Its optical antipodes have been separated in some of the salts (Fig. 4), and the rate of racemization studied. In strongly alkaline solution one of the 5 chelate rings slowly opens and Co(penten)OH 2+ is produced (Fig. 1), to which a first proton can be attached at the terminal NH 2 ‐group (→ Co(Hpenten)OH 3+ ), and a second which converts the hydroxo‐complex into the aquo‐complex (→ Co(Hpenten)OH 4+ ). The equilibria between Co(penten) 3+ , Co(penten)OH 2+ , Co(Hpenten)OH 3+ and Co‐(Hpenten)OH 2 4+ have been elucidated, and the kinetics of the ring opening and ring closing reactions have been studied. Ring opening and ring closure take place with retention of configuration. It proved impossible to open two of the chelate rings of Co(penten) 3+ . Cristalline salts with cations of the general formula Co(penten)X 3 −λ or Co (Hpeten)X 4−λ , with Xλ− OH−, H 2 O, F−, Cl−, Br−, J−, SCN−, NO 2 ,− and CO 3 2 −, have been obtained and characterized (Fig. 1, 2, 7 and Table 1).