The CO/PC analogy in coordination chemistry and catalysis

9 pagesThis short account summarizes recent results obtained in the coordination chemistry of phosphinines and emphasizes their analogy with CO ligands. Reduced complexes can be easily assembled through the reaction of reduced 2,2'-biphosphinine dianions with transition metal fragments. Theoretical calculations were performed to establish the oxidation state of the metal in these complexes. Though many reduced complexes are available, phosphinines proved to be too sensitive toward nucleophiles to be used as efficient ligands in most catalytic processes. However, the high electrophilicity of the phosphorus atom can be exploited to synthesize phosphacylohexadienyl anions which exhibit a surprising coordination chemistry. When phosphino sulfide groups are incorporated as ancillary tridentate anionic SPS ligands can be easily produced. These ligands can bind different transition metal fragments such as M-X (M = group 10 metal, X = halogen), Rh-L (L = 2 electron donor ligand), Cu-X and Au-X (X = halogen). Palladium(II) complexes proved to be active catalyst in the Miyaura cross-coupling reaction. Bidentate anionic PS ligands were also synthesized following a similar approach. Their Pd(II) (allyl) derivatives showed a very good activity in the Suzuki catalyzed cross-coupling process that allows the synthesis of biphenyl derivatives through the reaction of phenylboronic acid with bromoarenes

A 3D cellular context for the macromolecular world

We report the outcomes of the discussion initiated at the workshop entitled A 3D Cellular Context for the Macromolecular World and propose how data from emerging three-dimensional (3D) cellular imaging techniques—such as electron tomography, 3D scanning electron microscopy and soft X-ray tomography—should be archived, curated, validated and disseminated, to enable their interpretation and reuse by the biomedical community

Nouveaux ligands mixtes phosphore-soufre (coordination, catalyse et étude théorique)

PALAISEAU-Polytechnique (914772301) / SudocSudocFranceF

DFT study of the fixation of CO by SPS-based pincer Rh(I) and Ir(I) complexes: regioselectivity and reactivity.

7 pagesThe regioselectivity of the addition of CO on SPS-type pincer-based metal complexes is studied by means of DFr calculations on the unsubstituted model complexes [M(SPS)(PH3)] (M=Rh and Ir). The reaction leads to the decoordination of a sulphur centre and to the formation of the four-coordinate square-planar complex [M(SP)(PH3)(CO)], but the five-coordinate syn-SS complex [M(SPS)(PH3)(CO)] is found to be very close in energy (Delta E Delta E-bond(Rh-CO))

Regioselectivity of the addition of O2 on SPS-based Rh(I) and Ir(I) complexes.

6 pagesThe addition of O2 on SPS-type pincer-based Rh(I) and Ir(I) complexes was studied by means of DFT calculations. The regioselectivity and the influence of the nature of the metal center on the reaction thermicity were related through a thermodynamic cycle to the electronic properties of the metal complex and to the energetics of the M-O bonds. The synthesis and the X-ray crystal structure analysis of the Ir(I) complex are also presented

New anionic and dianionic polydentate systems featuring ancillary phosphinosulfides as ligands in coordination chemistry and catalysis.

International audienceThis article provides an overview of the chemistry of monoanionic S–P–S and dianionic S–C–S ligands featuring two phosphinosulfide ligands as pendant groups. These new pincer-type structures are easily assembled from phosphinines and the bis-sulfide derivative of the bis(diphenylphosphino)methane, respectively. Monoanionic S–P–S pincer ligands easily coordinate group 10 and group 9 metal fragments through displacement reactions. Palladium(II) complexes of S–P–S ligands efficiently catalyze cross-coupling processes, allowing the formation of boronic esters and biphenyl derivatives. Rh(I) complexes of S–P–S ligands react in a regioselective way with small molecules (O2, SO2, CS2, MeI) to afford the corresponding Rh(I) or Rh(III) derivatives. S–C–S dianonic ligands, which are readily obtained through a bis-metallation at the central carbon atom of Ph2P(double bond; length as m-dashS)CH2P(double bond; length as m-dashS)Ph2, react with Pd(II) and Ru(II) precursors to afford new carbene complexes. Samarium and thulium alkylidene complexes of these S–C–S dianionic ligands were synthesized in a similar way. Reaction of the lanthanide derivatives with ketones or aldehydes yields olefinic derivatives through a ‘Wittig-like' process

Anions of tridentate SPS ligands : Syntheses, X-ray structures and DFT calculations.

International audienc

Synthesis and X-ray Crystal Structure of a Cationic Homoleptic (SPS)2Rh(III) Complex and EPR Study of Its Reduction Process

Oxidation of the square planar Rh(I) complex [Rh(SPSMe)(PPh3)] (SPSMe = 1-methyl-1-P-2,6-bis(diphenylphosphinosulfide)-3,5-(bisphenyl)-phosphinine) (1) based on mixed SPS-pincer ligand with hexachloroethane yielded the Rh(III) dichloride complex [Rh(SPSMe)(PPh3)Cl2] (2), which was structurally characterized. The homoleptic Rh(III) complex [Rh(SPSMe)2][Cl] (4) was obtained via the stoichiometric reaction of SPSMe anion (3) with [Rh(tht)3Cl3] (tht = tetrahydrothiophene). Complex 4, which was characterized by X-ray diffraction, was also studied by cyclic voltammetry. Complex 4 can be reversibly reduced at E = −1.16 V (vs SCE) to give the neutral 19-electron Rh(II) complex [Rh(SPSMe)2] (5). Accordingly, complex 5 could be synthesized via chemical reduction of 4 with zinc dust. EPR spectra of complex 5 were obtained after electrochemical or chemical reduction of 4 in THF or CH2Cl2. Hyperfine interaction with two equivalent 31P nuclei was observed in liquid solution, while an additional coupling with a spin 1/2 nucleus, probably 103Rh, was detected in frozen solution. The 31P couplings are consistent with DFT calculations that predict a drastic increase in the axial P−S bond lengths when reducing (SPSMe)2Rh(III). In the reduced complex, the unpaired electron is mainly localized in a rhodium dz2 orbital, consistent with the g-anisotropy measured at 100 K

The Effect of a Fourth Binding Site on the Stabilization of Cationic SPS Pincer Palladium Complexes : Experimental, DFT, and Mass Spectrometric Studies

International audienc