Showing papers by "Catherine Belle published in 2018"
TL;DR: DFT and TD-DFT calculations support the formation of a CuIICuIII phenoxido-hydroxido complex, and the bis-amide moiety appears to be a non-innocent proton acceptor along the redox process.
Abstract: A (μ-hydroxido, μ-phenoxido)CuIICuII complex 1 has been synthesized using an unsymmetrical ligand bearing an N,N-bis(2-pyridyl)methylamine (BPA) moiety coordinating one copper and a dianionic bis-amide moiety coordinating the other copper(II) ion. Electrochemical mono-oxidation of the complex in DMF occurs reversibly at 213 K at E1/2 = 0.12 V vs Fc+/Fc through a metal-centered process. The resulting species (complex 1+) is only stable at low temperature and has been spectroscopically characterized by UV–vis–NIR cryo-spectroelectrochemical and EPR methods. DFT and TD-DFT calculations, consistent with experimental data, support the formation of a CuIICuIII phenoxido-hydroxido complex. Low-temperature chemical oxidation of 1 by NOSbF6 yields a tetranuclear complex 2(SbF6)(NO2) which displays two binuclear CuIICuII subunits. The X-ray crystal structure of 2(SbF6)(NO2) evidences that the nitrogen of the terminal amide group is protonated and the coordination of the amide occurs via the O atom. The bis-amide mo...
11 citations
TL;DR: Analysis in acetonitrile solution of structure-property relationships has been carried out by comparing their UV/Vis, electrochemistry, ESI-MS, and NMR properties with trends from computational calculations (DFT).
Abstract: We report on the synthesis of new dinucleating phenol-based "end-off" compartmental ligands HLMeH and HLMe2 bearing two different binding sites, one bis(2-methylpyridyl)aminomethyl (BPA) and one thiosemicarbazone (TSC) site, and their corresponding copper(ii) complexes 1t and 2d. With the ligand HLMeH, a tetranuclear entity (1t) has been isolated in the solid state, whereas with HLMe2, which differs from HLMeH by a methyl substituent on the N-terminal amino group of the TSC arm, a dinuclear form (2d) is obtained. X-ray crystallography analysis shows that the nuclearity di vs. tetra is modulated by interactions between copper atoms and hydroxido bridges along with the sulphur atoms of TSC arms. From a magnetic point of view, 1t can be considered as an association of two dinuclear forms leading for both complexes to overall antiferromagnetic coupling. Analysis in acetonitrile solution of structure-property relationships has been carried out by comparing their UV/Vis, electrochemistry, ESI-MS, and NMR (variable temperature and DOSY = diffusion ordered spectroscopy) properties with trends from computational calculations (DFT). HRMAS-DOSY (High Resolution Magic Angle Spinning) NMR spectroscopy has been performed to evaluate the presence of different species in solution at room temperature.
9 citations