117677-76-6Relevant academic research and scientific papers
Kinetics of ligand substitution in bis(N-alkylsalicylaldiminato)nickel(II) complexes: A search for kinetically-effective aromatic ring stacking
Buesing,Elias,Eslick,Wannowius
, p. 223 - 226 (1988)
The square-planar bis chelate complexes Ni(R-sal)2 (= bis(N-alkyl)salicylaldiminato)nickel(II)) with R = -(CH2)2-Ph (I; Ph = phenyl), -(CH2)3-Ph (II), -(CH2)4-Ph (III) and -(CH2)2-(4-hydroxyphenyl) (IV) were prepared and characterized. Complexes II and III meet the steric requirements for intramolecular aromatic ring stacking. Stopped-flow spectrophotometry was used to study the kinetics of ligand substitution in complexes I-IV by H2salen (= N,N′-disalicylidene-ethylenediamine) in acetone. For the substitution of the two bidentate ligands in Ni(R-sal)2 only one step is kinetically observed which follows a second-order rate law, rate = k[H2salen] [Ni(R-sal)2], with k = 43.4 (I), 64.0 (II), 87.0 (III) and 49.5 (IV) M-1 s-1 at 298 K. It is found, therefore, that the size of k does not change significantly upon lengthening of the alkane chain in Ni(Ph-(CH2)n-sal)2 from n = 2 to 4 and that there is no kinetic evidence for intramolecular stacking interactions. The equilibrium constants and thermodynamic parameters for the formation of the bis adducts III·(py)2 and III·(MeOH)2 in acetone are reported.
