title: A novel di-compartmental bis-(2-hydroxyisophtalamide) macrocyclic ligand and its mononuclear Cu(II) and Ni(II) complexes.
abstract: The synthesis and characterisation of the new di-compartmental bis-(2-hydroxyisophtalamide) macrocyclic pro-ligand, LH(6), which comprises two phenol-diamide units linked by ethylene bridges, is herein reported, together with its corresponding di-phenolate salt, [NBu(4)](2)[LH(4)]. The three macrocyclic compounds, [LH(4)(OMe)(2)] (protected ligand), LH(6) and [LH(4)][NBu(4)](2) were fully characterised including X-ray crystallography for [LH(4)(OMe)(2)] and [NBu(4)](2)[LH(4)]. The results of solid-state and solution studies have indicated that the macrocycle can adopt specific conformations, which are influenced by H-bonding interactions as well as the deviation of the amide carbonyl relative to the phenol plane. LH(6) reacts with M(II)(acetate)(2)·(H(2)O)(6) (M = Ni, Cu) in a 1 : 1 ratio in the presence of 4 eq of [NBu(4)](OH) in methanol to afford the dianionic [M(LH(2))](2-) complexes, (2-) and (2-), respectively. The X-ray crystallography, EPR, NMR and UV-vis spectroscopic data, combined with DFT calculations, indicate that (2-) and (2-) are unique unsymmetrical square planar mononuclear complexes that are intramolecularly H-bonded. Thus, one macrocyclic compartment contains a M(II)-N(2)O(2) centre resulting from the tetra-anionic di-phenolato di-amidato ligation; the other compartment possesses two protonated amide N-H groups that are H-bonded the coordinated phenolate O atoms. This represents a unique example in which a phenolate is both coordinated and intramolecularly H-bonded. This H-bonding appears unusually strong as revealed by N(H/D) exchange experiments; and may be responsible for the stability of the mononuclear complex, and the difficulty in isolating the corresponding dinuclear complex [M(2)(L)](2-).
authors.affiliation: Department of Chemistry, Bar-Ilan University, Ramat Gan 52 900, Israel.
authors.forename: Meital
authors.initials: M
authors.lastname: Eckshtain-Levi
authors.forename: Ronit
authors.initials: R
authors.lastname: Lavi
authors.forename: Dmitry
authors.initials: D
authors.lastname: Yufit
authors.forename: Maylis
authors.initials: M
authors.lastname: Orio
authors.forename: Riccardo
authors.initials: R
authors.lastname: Wanke
authors.forename: Laurent
authors.initials: L
authors.lastname: Benisvy