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Composés d'addition des halogénures de niobium(V) et de tantale(V): VI. Réactions d'échange des composés du chlorure de niobium(V) avec quelques nitriles
Author(s) -
Merbach A.,
Bünzli J. C.
Publication year - 1972
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.19720550607
Subject(s) - chemistry , niobium , adduct , enthalpy , stereochemistry , medicinal chemistry , crystallography , thermodynamics , organic chemistry , physics
The ligand exchange reactions NbCl 5 ·ŘN + RCN* ⇄ NbCl 5 · RCN* + RCN are studied by NMR. spectroscopy for R = Me 3 C, Me, FCH 2 , CICH 2 , BrCH 2 , ICH 2 . The reaction is of zero order in RCN and of first order in NbCl 5 · RCN and thus a dissociative mechanism is suggested for all the ligands studied. The enthalpies and entropies of activation are determined over 50° to 90° temperature ranges. There is a linear correlation between ΔG≠ and the free enthalpy of formation of NbCl 5 RCN. However this correlation is shown to hold only for series of adducts having the same donor group.