Abdelaziz Jouaiti

Synthesis of new chelating agents : association of a phosphaalkene moiety with a pyridine

Molecules containing a Pyridine ring located in α from one or two phosphaalkene moieties have been synthesized. The E isomer (L1) and the E,E isomer (L2) are well suited for acting as a bidentate and a trindentate ligand respectively. The crystal structure ofthe E isomer (L1) is determined.

Phosphaalkene derivatives of furane and thiophene: Synthesis, crystal structure, electrochemistry and EPR study of their radical anions

Two phosphaalkenes containing either a furane or a thiophene ring bound to the carbon atom of the −Pdouble bond; length as m-dashC < bond have been synthesized. The crystal structure of the furane derivative has been determined and the electrochemistry of both compounds has been investigated. THF solutions of these compounds react at 255 K with a potassium mirror to yield the corresponding radical anions which have been studied by EPR in both the liquid and solid states. The resulting hyperfine constants are compared with the values predicted by ab initio calculations on radical anions formed from model phosphaalkenes.

Metallacrown ethers: synthesis and structural investigation of silver metallamacrocycles

The bis-monodentate ligands 1 and 2 based on the interconnection of two pyrazolyl units by CH 2 (CH 2 OCH 2 ) n CH 2 ( n =3 or 4) spacers, respectively, lead to the formation of either mono nuclear silver metallamacrocycle 10 in the case of 1 or binuclear silver metallamacrocycle 11 in the case of 2 . Both complexes have been characterised in the solid state by X-ray diffraction on single crystals.

Spin delocalization in radical anions containing two phosphaalkene groups: an EPR study

The radical anions of various isomers of phenyldiphosphaalkenes were generated by electrochemical and chemical reductions. The resulting EPR spectra in liquid and frozen solutions show that the spin delocalization on the phosphaalkene groups is dependent upon the nature of the isomer. The corresponding spin densities are compared with those predicted by DFT calculations on model diphosphaalkene anions. The role of the bridging group between the two PC bonds was investigated by studying the diphosphaalkene derivatives of diphenyl and furan. Copyright

Controlling the formation of discrete complexes or a1-D directional coordination network by the binding ability ofanions

Based on the coordination ability of ClO4−, BF4− and Cl− anions, a switch from discrete octahedral Co(II) complexes to a directional 1-D network was demonstrated using organic tectons based on a pyridine unit as a monodentate coordination site and a terpyridine moiety as a tridentate coordination pole; whereas with non-coordinating anions discrete mononuclear complexes were obtained, for Cl− anion a 1-D coordination network was obtained in the presence of CoCl2 under self-assembly conditions; the X-ray study on a single crystal revealed the centrosymmetric packing of the 1-D networks.

Synthesis and characterisation of a heterodinuclear ruthenium( II) - palladium( II) complex with two different cyclometallating sites

Abstract A bis-cyclometallating ligand bearing two different terdentate coordination sites (NCN: dipyridyI-benzene; PCP: diphosphaalkenebenzene moieties) has been synthesised. Selective reactions of appropriate metal complex precursors afforded a heterodinuclear ruthenium(II)-palladium(II) complex characterised by 1 H, 13 P NMR spectroscopy and FAB-MS techniques. We have compared its electrochemical and spectroscopic properties (absorption and emission) with the individual ruthenium(II) and palladium(II) subunits.

EPR study of phosphafulvene radical anions

Cyclic voltammetry of phosphafulvene and dibenzophosphafulvene shows that in DMF these compounds are reduced at -1.200 and -1.349 V, respectively. The EPR spectra of the corresponding radical anions, formed by electrochemical reduction or by reaction on a potassium mirror, are recorded between 110 K and room temperature. The g and 31P hyperfine tensors are measured and compared to those previously obtained for a phosphaalkene radical anion. Abinitio investigations on model phosphaalkene and phosphafulvene radical anions show that, in accord with the experimental results, the electronic structure of these two species are quite different: whereas the unpaired electron is delocalized on the whole PC(H)R moiety in the phosphaalkenic anion, it is markedly localized on the phosphorus atom in the phosphafulvene anion. Calculated spin densities and charge distributions for phosphafulvene and azafulvene anions are compared.

1,2-Bis[2-(2,4,6-tri-tert-butylphenyl)phosphanediylmethyl]benzene, L: synthesis and structure of L, of the chelated complex [PdLCl2] and of a derived cyclometallated chiral complex

The synthesis and crystal structure of 1,2-bis[2-(2,4,6-tri-tert-butylphenyl)phosphanediylmethyl]benzene, L, are reported as well as the preparation and conformation of the novel seven-membered ring complex [PdLCl2]; this complex reacts with alcohols (MeOH, EtOH) to give a chiral cyclometallated complex [rac(R)P, (R)C; (S)P, (S)C] where the metal is bound to both a phosphaalkene and a phosphite phosphorus atom.

Synthesis, structure and ligand-centred reduction of an orthometallated complex of palladium containing two phosphaalkene groups

A novel ligand containing two phosphaalkene moieties has been synthesized, which forms a palladium(II) complex whose crystal structure has been determined and whose reduction has been shown, by EPR spectroscopy, to take place on the ligand rather than on the metal.

An EPR/ENDOR study of the reduction products of symmetrical isomers of dipyridylacetylene

The reduction potentials of the three symmetrical isomers (para–para, ortho–ortho and meta–meta) of dipyridylacetylene were measured by cyclic voltametry. These compounds were reacted on alkali metal mirrors and the resulting radical anions were studied by electron paramagnetic resonance/electron–nuclear double resonance/triple resonance spectroscopies. The reduction products were identified after comparison of the measured hyperfine couplings with those predicted by density functional theory calculations. The mono-radical anion was observed for the two former isomers [coupling with the counter ion was detected for the ion pair (ortho–ortho)-39K+]; the third isomer led to the radical anion of dipyridylethylene.