A novel di-compartmental bis-(2-hydroxyisophtalamide) macrocyclic ligand and its mononuclear Cu(ii) and Ni(ii) complexes

Meital Eckshtain-Levi, Ronit Lavi, Dmitry Yufit, Maylis Orio, Riccardo Wanke, Laurent Benisvy

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


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 2O) 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, 1 2- and 2 2-, respectively. The X-ray crystallography, EPR, NMR and UV-vis spectroscopic data, combined with DFT calculations, indicate that 1 2- and 2 2- are unique unsymmetrical square planar mononuclear complexes that are intramolecularly H-bonded. Thus, one macrocyclic compartment contains a M II-N 2O 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-.

Original languageEnglish
Pages (from-to)12457-12467
Number of pages11
JournalDalton Transactions
Issue number40
StatePublished - 28 Oct 2012


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