Separation of geometric isomers of a dicopper complex by using a (19)F-labeled ligand: dynamics, structures, and DFT calculations.
Introducing a fluorine group on two pyridines of the HL(CH(3)) ligand (2,6-bis[(bis(2-pyridylmethyl)amino)methyl]-4-methylphenol) allows the separation of two geometric isomers after complexation by two copper(II) ions. Methods for isolating the isomers (1(meso) and 1(rac)) as a mu-phenoxo,mu-hydroxo dicopper(II) complex as a crystalline product have been developed. Both isomers (1(meso) and 1(rac)) have been characterized by X-ray crystallography and (19)F NMR. The isomerism is determined by the disposition of the fluorine atoms with respect to the plane containing the Cu(2)O(2) core. Density functional theory calculations using different functionals were performed to provide additional support for the existence of these two forms. Dissolution of 1(meso) in acetone or acetonitrile causes its spontaneous isomerization into the 1(rac) form at room temperature. Combined experimental studies (UV-vis, (19)F NMR) and theoretical calculations support this process. Paramagnetic (19)F NMR appears as a unique and powerful probe for distinguishing the two isomers and supplying direct evidence of this isomerization process in solution.
Durot
Stéphanie
S
Département de Chimie Moléculaire, Université Joseph Fourier, équipes CIRE et Chimie Théorique UMR-CNRS 5250, ICMG FR-2607, BP 53, 38041 Grenoble Cedex 9, France.
Hossain
Laila H
LH
Hamman
Sylvain
S
Jamet
Hélène
H
Orio
Maylis
M
Gautier-Luneau
Isabelle
I
Luneau
Dominique
D
Philouze
Christian
C
Pierre
Jean-Louis
JL
Belle
Catherine
C