Claudine Pascard

Chirality directed self-assembly. Resolution of 2,5-diazabicyclo[2.2.2]octane-3,6-dione and crystal structures of its racemic and (−) enantiomeric forms

The chiral bicyclic bis-lactam 1 has been resolved and the crystal structures of the racemate (±)-1 and of enantiomerically pure (−)-1 have been determined. They show that the chiral nature of the substance determines the supramolecular architecture generated by hydrogen bonding self-assembly, giving an infinite zig-zag chain for the racemate and a cyclic tetramer for the enantiomer.

Statistical analysis of noncovalent interactions of anion groups in crystal structures. I. Hydrogen bonding of sulfate anions

The hydrogen-bond acceptor characteristics of sulfate dianions are analyzed in crystal structures of small molecules. For 85 anions, neither coordinated to metal ions nor covalently bonded, 697 hydrogen bonds are faund. Of these, 266 (38%) are the O⋯H—O type and 431 (62%) are the O⋯H—N type, proportions that correspond well to the stoichiometry of the compounds studied and indicate no preference for a particular donor. The analysis of the data set, after classifying the hydrogen bonds according to the different types of donors, shows that O⋯H—O bonds are more linear than O⋯H—N. The anion oxygen–acceptor function is characterized by multiple hydrogen bonding. Only in 56 cases does a sulfate oxygen participate in a single hydrogen bond. In most cases every sulfate oxygen is coordinated by two (187 cases) or three (89 cases) hydrogen bonds. For three H donors, the preferred coordination geometry of the sulfate oxygen is pyramidal. The most frequent coordination around a sulfate dianion is with eight to ten H donors. Thus, sulfate dianions can play a significant cohesive role in molecular aggregation.

X-ray investigation of glyoxime derivatives. V. Two isomers of 2-(thienyl)glyoxime. A database study of the geometry and hydrogen bonding of the oxime group

The crystal structures of two isomers of 2-(thienyl)glyoxime, 2-thienylethanedial dioxime, C 6 H 6 N 2 O 2 S, E,E [orthorhombic, Pbca, a=11.074 (5), b=9.152 (3), c=14.660 (4) A, V=1185.84 A 3 , D x =1.522 g cm -3 , Z=8, R=0.058 for 1276 reflections with I>3σ(I)] and E,Z [monoclinic, P2/c, a=12.189 (3), b=3.865 (3), c=16.022 (5) A, β=90.79 (2) o , V=754.8 A 3 , D x =1.498 g cm -3 , Z=4, R = 0.032 for 1154 reflections with I>3σ(I)] have been determined. An analysis based on the structures of the title compounds and on other glyoxime derivatives showed that the E,E configuration is the preferred form. A statistical study on the geometry of the oxime group and on hydrogen bonding in the oximes was performed using the Cambridge Structural Database

Structure et proprietes chimiques du complexe Cp(DPPE)FeCOPh. Preparation de complexes carbeniques

Abstract Cp(DPPE)Fe(COPh) (A) can be prepared either by reaction of benzoyl chloride with the inorganic Grignard reagent Cp(DPPE)FeMgBr or by irradiation of Cp(CO)2Fe(COPh) in the presence of DPPE. Complex A Shows a particularly low carbonyl absorption in the infrared spectrum: 1510 cm−1. The crystal structure determination shows a distorted geometry for the benzoyl group. A is a precursor for carbene complexes which do not contain carbonyl ligands.

New macrocyclic ligands. X-Ray study of three macrocycles involving azofurazan subunit

Abstract The first X-Ray crystallographic analysis of conformationally immobilized polyfurazan macrocycles, involving both a furazan ring and an azo-group has been carried out. The configurational and conformational features observed in the crystal have been analysed; all results show that the intramolecular non-bonded interactions influence the observed conformation.

A cyclometallated iridium(III) dimethylphenylphosphine complex

[Ir(cod)Cl] 2 (cod = 1,5-cyclooctadiene) reacts with PMe 2 Ph in CH 3 CN to give the red cation [Ir(PMe 2 Ph) 4 ] + . This complex in CH 3 CN reacts with H 2 to give cis -[IrH 2 (PMe 2 Ph) 4 ] + , but on reflux for 6 h in the absence of H 2 , it gives the first example of a cyclometallated PMe 2 Ph complex fac -[IrH(PMe 2 C 6 H 4 )(PMe 2 Ph) 3 ] + , as shown by PMR spectroscopy and preliminary X-ray crystallographic data.

Vermiculinol and vermiculidiol, macrodiolides from the fungus Penicillium vermiculatum

Abstract Two macrodiolides, vermiculinol and vermiculidiol have been isolated from a culture of the fungus Penicillium vermiculatum and their structures elucidated from a spectroscopic study including IR, MS, NMR and X-ray crystallography and chemical transformations.

Binuclear Copper(II) Complexes of Cyclo-Bis Intercaland Receptors. Effect of the Ligand on the Crystal Structure and Complexation Properties

There has been considerable interest in metal complexes of binucleating ligands as models for the coordination environment of the active sites in binucleating metalloenzymes. Numerous synthetic systems, like di-copper or di-cobalt complexes, have been demonstrated to function as catalysts for the transformation (oxidation, hydrolysis) of organic substrates other than the ligand itself. The catalytic efficiency and the selectivity depends critically on the distance between the metallic centers, the conformation of the spacer and the stability of the complex.