ISSN:
1572-901X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Summary Halogenation of LnIII, CeIV and ZrOII β-diketone/β-ketoester derivatives and their mixed ligand complexes of the types Ln(AA)2(Sal) and Ln(AA)(Sal)2 by NCS, NBS and PyHBr3 yield different isomeric products depending on the nature of the solvent medium, the reagent and the reaction time. The halogenation, if carried out in glacial acetic acid, irrespective of the reagent, yields the stable S-hall, product wherein the three chelate rings remain imperturbed in respect of metal coordination. When the reaction is carried out in 5% v/v DMF-CHCl3 employingN-halosuccinimide and maintaining correct reaction times, it is possible to isolate individually three other isomeric products. The isomers prepared are Ln(OO)3, Ln(OO)2(OX), Ln(OO)(OX)2 and Ln(OX)3 where (OO) represents diketone oxygen linkage and (OX) represents diketone oxygen and substituted halogen linkage to the central metal ion. The four linkage isomers have been identified by a comparison of the number of observed3H n.m.r. or13C n.m.r. signals with those expected for a given isomer on the basis of symmetry considerations in the tris-chelated octahedral structures.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01177465
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