Laure Vendier

Single-Laser-Shot-Induced Complete Bidirectional Spin Transition at Room Temperature in Single Crystals of (FeII(pyrazine)(Pt(CN)4))

Single crystals of the {Fe (II)(pyrazine)[Pt(CN) 4]} spin crossover complex were synthesized by a slow diffusion method. The crystals exhibit a thermal spin transition around room temperature (298 K), which is accompanied by a 14 K wide hysteresis loop. X-ray single-crystal analysis confirms that this compound crystallizes in the tetragonal P4/ mmm space group in both spin states. Within the thermal hysteresis region a complete bidirectional photoconversion was induced between the two phases (high spin right arrow over left arrow low spin) when a short single laser pulse (4 ns, 532 nm) was shined on the sample.

A practical, cheap and environmentally friendly preparation of bismuth(III) trifluoromethanesulfonate

A method for large scale preparation of Bi(OTf)3 from Bi2O3 in a weakly hydrated form after freeze-drying.

Ruthenium-Catalyzed Hydrogenation of Nitriles: Insights into the Mechanism

Hydrogenation of benzonitrile into benzylamine is catalyzed under very mild conditions by the ruthenium bis(dihydrogen) complex RuH(2)(H(2))(2)(PCyp(3))(2), incorporating two tricyclopentylphosphines. Two key intermediates have been isolated, resulting from the activation of benzonitrile at early stages of activation, i.e., either N-coordination through the nitrile function or first hydrogenation with benzylimine formation, followed by, thanks to C-H activation, coordination at ruthenium as an orthometalated ligand.

Ruthenium-Catalyzed Reduction of Carbon Dioxide to Formaldehyde

Functionalization of CO2 is a challenging goal and precedents exist for the generation of HCOOH, CO, CH3OH, and CH4 in mild conditions. In this series, CH2O, a very reactive molecule, remains an elementary C1 building block to be observed. Herein we report the direct observation of free formaldehyde from the borane reduction of CO2 catalyzed by a polyhydride ruthenium complex. Guided by mechanistic studies, we disclose the selective trapping of formaldehyde by in situ condensation with a primary amine into the corresponding imine in very mild conditions. Subsequent hydrolysis into amine and a formalin solution demonstrates for the first time that CO2 can be used as a C1 feedstock to produce formaldehyde.

A terminal borylene ruthenium complex: from B-H activation to reversible hydrogen release.

Starting from RuHCl(H2)(PCy3)2, a terminal ruthenium mesitylborylene complex was obtained via double B-H bond activation of mesitylborane and concomitant release of dihydrogen, such a process being remarkably reversible.

Iron-Catalyzed C–H Borylation of Arenes

Well-defined iron bis(diphosphine) complexes are active catalysts for the dehydrogenative C-H borylation of aromatic and heteroaromatic derivatives with pinacolborane. The corresponding borylated compounds were isolated in moderate to good yields (25-73%) with a 5 mol% catalyst loading under UV irradiation (350 nm) at room temperature. Stoichiometric reactivity studies and isolation of an original trans-hydrido(boryl)iron complex, Fe(H)(Bpin)(dmpe)2, allowed us to propose a mechanism showing the role of some key catalytic species.

Trioxaferroquines as new hybrid antimalarial drugs.

The synthesis, characterization, and antimalarial evaluation of a new series of potential antimalarial molecules, named trioxaferroquines, are reported. Trioxaferroquines are hybrid antimalarial drugs containing a 1,2,4-trioxane covalently linked to ferroquine (Fq), a synthetic ferrocenylquinoline derivative currently under clinical development. The aim was to combine, within a single structure, an iron(II) species, a 1,2,4-trioxane, as in artemisinin, and a substituted quinoline, as in chloroquine.

Experimental evidence for the participation of 5d Gd(III) orbitals in the magnetic interaction in Ni-Gd complexes.

The syntheses, structural determinations, and magnetic studies of two trinuclear Ni-Gd-Ni complexes are described. The structural studies demonstrate that the two complexes present a linear arrangement of the Ni and Gd ions, with Ni ions in slightly distorted square-pyramidal or octahedral environments in complexes 1 and 2, respectively. The Ni and Gd ions are linked by two or three phenoxo bridges, so that complexes 1 and 2 present edge-sharing or face-sharing bridging cores. Ferromagnetic interactions operate in these complexes. While a unique J parameter is able to fit the magnetic data of complex 2, two very different J constants are needed for 1. This result is at first sight surprising, for the structural data of the two Ni-O(2)-Gd cores in complex 1 are quite similar (similar Ni-O and Gd-O bond lengths, similar angles, and dihedral angles), the only difference coming from the angle between the planes defined by the Gd ion and the two bridging phenoxo oxygen atoms of each Ni-O(2)-Gd half core. This latter magnetic behavior can be considered as a signature for the participation of 5d Gd(III) orbitals in the exchange interaction mechanism and can explain why edge-sharing complexes have larger J parameters than face-sharing complexes.

NHC-derived bis(amidiniophosphine) ligands of Rh(I) complexes: versatile cis-trans chelation driven by an interplay of electrostatic and orbital effects.

The synthesis, structure, and electronic properties of a dicationic bis(amidiniophosphine) based on an o-phenylene bridge is described. In spite of the presence of two facing P-conjugated positive charges, this electron-poor diphosphine is shown to act as a versatile chelating ligand in a series of stable rhodium(I) complexes. IR analysis of a carbonyl complex showed that the sigma-donating versus pi-accepting character of the cationic ligand is comparable to that of a neutral trialkylphosphite. While the ligand is trans-chelating at a neutral Rh(I) center, it switches to cis-chelating at a cationic Rh(+) center. This and other unusual geometrical features revealed by X-ray diffraction analyses are interpreted by a subtle interplay between antisymbiotic trans preference, electrostatic repulsion, and relative Lewis acidity of the transition metal centers.

A single molecule magnet (SMM) with a helicate structure

The X-ray structure determination of [L2Cu2Gd2(NO3)6(H2O)2](0.5H2O) (L = bis-[(2-hydroxy-3-ethoxyphenyl)methylene]-4,4′-methylenedianiline) confirms the existence of a tetranuclear double-stranded homotopic and unsaturated helicate. In each Cu–Gd pair, the reduced Cu⋯Gd distance allows ferromagnetic Cu–Gd superexchange interactions through two phenoxo oxygen atoms. Replacement of gadolinium ions by terbium ions yields the first example of a helicate behaving as a single molecule magnet (SMM).