Sylvain Hamman

Effet de la concentration en acide fluorhydrique dans la pyridine sur la regio-selective de la fluoration par deamination d′α-amino-esters : syntheses de composes cargoxyles-β-fluores.

Resume Fluorodeamination of α-amino-esters with sodium nitrite in HF-pyridine gives mainly β-fluoro-esters. The molar ratio HF-pyridine is the main parameter for the α-β regioselectivity.

Heterodinuclear Cu(II)Zn(II) complexes: 19F NMR as a versatile tool to control the synthesis

Abstract The dinucleating ligands 2,6-bis[(bis(2-pyridylmethyl)amino)methyl]-4-methylphenol (H-BPMP) and 2,6-bis[(bis(2-pyridylmethyl)amino)methyl]-4-fluorophenol (H-BPFP) were used to synthesize heterodinuclear (μ-phenoxo)(μ-hydroxo) Cu(II)Zn(II) complexes. The labeled ligand with a fluorine atom allows the use of 19F NMR spectroscopy, which turned to be a rapid and powerful tool to tune the synthesis of the heterodinuclear paramagnetic complex [CuZnBPFP(μOH)](ClO4)2 and avoid mixing of complexes with statistical distribution. When applied to the non-fluorinated ligand, this experimental procedure leads to prepare and isolate easily the complex [CuZnBPMP(μOH)](ClO4)2. The X-ray structure is described.

Stereochemical assignment of the meridional isomer of the trisbidentate chelate complex Ga(fox)3 (fox = 5‐fluoro‐8‐hydroxyquinoline) by two‐dimensional correlated NMR

The complete assignments of all 19F, 1H and 13C resonances for the mer isomer of Ga(fox)3 (fox = 5‐fluoro‐8‐hydroxyquinoline) by analysis of scalar (COSY) and dipolar (NOESY) connectivities were demonstrated, resulting in an unambiguous structural determination of the complex under investigation. Detailed one‐ and two‐dimensional multinuclear NMR investigations were carried out to obtain the spectral patterns characteristic of the Ga(fox)3 complex. Copyright

Separation of Geometric Isomers of a Dicopper Complex by Using a 19F-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.