1404064-23-8Relevant academic research and scientific papers
A novel di-compartmental bis-(2-hydroxyisophtalamide) macrocyclic ligand and its mononuclear Cu(ii) and Ni(ii) complexes
Eckshtain-Levi, Meital,Lavi, Ronit,Benisvy, Laurent,Yufit, Dmitry,Orio, Maylis,Wanke, Riccardo
, p. 12457 - 12467,11 (2012)
The synthesis and characterisation of the new di-compartmental bis-(2-hydroxyisophtalamide) macrocyclic pro-ligand, LH6, which comprises two phenol-diamide units linked by ethylene bridges, is herein reported, together with its corresponding di-phenolate salt, [NBu 4]2[LH4]. The three macrocyclic compounds, [LH4(OMe)2] (protected ligand), LH6 and [LH4][NBu4]2 were fully characterised including X-ray crystallography for [LH4(OMe)2] and [NBu 4]2[LH4]. 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. LH6 reacts with MII(acetate)2·(H2O) 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(LH2)] 2- complexes, 12- and 22-, respectively. The X-ray crystallography, EPR, NMR and UV-vis spectroscopic data, combined with DFT calculations, indicate that 12- and 22- are unique unsymmetrical square planar mononuclear complexes that are intramolecularly H-bonded. Thus, one macrocyclic compartment contains a MII-N 2O2 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 [M2(L)]2-.
