Ousmane Diallo

Catalytic intermolecular hydroamination of alkenes: Beneficial effect of ionic solvents

Rhodium(III) pre-catalysts exhibit a much higher catalytic activity in ionic solvents (phosphonium or imidazolium salts) than in THF for the hydroamination of norbornene with aniline. The nature of the anionic part of the ionic solvent seems to play an important part, bromides ions being the more efficient in increasing the catalytic activity. For the same reaction, the activity of platinum(II) pre-catalysts is evidenced for the first time, and is also increased when used in tetrabutylphosphonium bromide as solvent. The catalytic activity and selectivity also depend upon the nature of the ligands in the platinum precursor.

Spirophosphazenes and the parent triazaphosphole : differences and similarity in chemical reactivity

Abstract The first step of hydrolysis of compounds 1 , 2 and 4 involves the protonation of the PN nitrogen atom. 3 does not react with water in the absence of a catalyst. Protonation of compounds 1 – 3 by a strong acid such as CF3SO3H is studied by 15N and 31P nmr spectroscopy. In all cases the PN nitrogen appears to be the strongest basic site.

Coordination chemistry of mononuclear iron carbonyl complexes

Abstract This review is devoted to recent advances in mononuclear iron carbonyl coordination chemistry starting from M+[EFe(CO)4]− complexes (E=H, RCO) easily obtained from Fe(CO)5. E=H. The reaction of K+[HFe(CO)4]− with phosphines, phosphites and phosphinites (abbreviated “P”) allows selective syntheses for a large range of (phosphane)iron carbonyl complexes such as Fe(CO)3P2, Fe(CO)2P3, H2Fe(CO)2P2, K+[HFe(CO)3P]− and K+[HFe(CO)2P2]−. In the special case of the new optically active phosphinite–ammonium ligands P–(*)–N+ named “ephosium” and “valphosium”, optically active zwitterionic complexes [HFe(CO)3P]−–(*)–N+ have been obtained, the structures of which have been studied both in the solid state and in solution. The above reactions have been shown to involve first a CO substitution, generating [HFe(CO)3P]− species which then react further, the final product depending on both the nature of the solvent (protic or not) and the steric and electronic properties of the phosphane. In contrast, reaction with tri(amino)phosphines proceeds by substitution at the phosphorus atom, affording the Collman dianion [Fe(CO)4]2− and [(R2N)2PH]Fe(CO)4 complexes the reactivities of which with KH have been studied. E=RCO. The reaction of lithium aldimines such as [t-BuNC(t-Bu)]Li with Fe(CO)5 generates lithium (α-iminoacyl)tetracarbonylferrates, which are imino-protected equivalents of the rare [(CO)4Fe–CO–CO–Z]− sequence. Alkylation with Me3OBF4 yields the corresponding α,β-unsaturated Fischer carbene complexes. The reaction of RCO(Li)Fe(CO)4 (R=alkyl) with PPh2Cl (or PPhCl2) cleanly proceeds by a tandem acylation–complexation to afford the complexed acylphosphines [RCOPPh2]Fe(CO)4 (or [RCOPPhCl]Fe(CO)4) in good yield.

ETUDE CINETIQUE DU MECANISME D'ADDITION DE L'ALCOOL TERTIOBUTYLIQUE SUR UN AMIDOPHOSPHITE BICYCLIQUE

Abstract The addition of tertiary butanol on a bicycloamidophosphite is stereospecific and leads to a bicyclophosphorane according to a second order kinetic. The activation parameters and isotopic effect were determined. These results suggest the formation of a phosphonium intermediate followed by an attack by the alcoolate anion, in agreement with the stereochemistry of the reaction.

Thermal Behaviour of Some Organ0 Phosphorus Compounds

Abstract So far organophosphorus chemists have been interested in synthesizing low coordinated phosphorus compounds and in studying them in solution at temperatures rarely above 300 °C. As a matter of fact there are few reports on the behaviour of dicoordinated phosphorus molecules at temperatures above 500 °C under low pressure. Another interesting point is that such a study would allow to assess the correla- tion between mass spectral processes and thermal ones.

IN-SITU SYNTHESES OF ALKYLLITHIUM COMPOUNDS UNDER ULTRASONIC IRRADIATION

Abstract The syntheses of organometallics such as alkyllithium compounds are performed. Furan and thiophene derivatives were prepared. Parameters which influence the yield have been optimized. The more important were the physical states of lithium and its sodium content and the nature of the substrate.

The reaction of potassium hydridopentacarbonylchromate with acrylates. X-ray structure of [PPN]+[CH3CH(COOEt)Cr(CO)5]−

KHCr(CO) 5 reacts with methyl acrylate in acetonitrile to give methyl propionate after acid hydrolysis. Monitoring the reaction by IR and NMR spectroscopy showed that the reaction mainly proceeds through the 1,2-addition product K + [CH 3 CH(COOMe)Cr(CO) 5 ] − . However, in situ formation of methyl propionate (ca. 15%) before hydrolysis suggests that part of the reaction also occurs through the 1,4-adduct K + [CH 3 CHC(OMe)OCr(CO) 5 ] − . The PPN + salt of the 1,2-adduct obtained from ethyl acrylate was characterized by single crystal X-ray diffraction.

In-situ formation and NMR characterization of the iridium(III) dihydride (PEt3)3IrH2Cl from the iridium(I) dinuclear complex [(C8H14)2lrCl]2 and PEt3

Abstract Reaction of the dinuclear complex [(C 8 H 14 ) 2 IrCl] 2 with PEt 3 (2 equiv./Ir) in THF at room temperature does not afford the expected [(PEt 3 ) 2 IrCl] 2 complex. Instead, a mixture of the mononuclear complex (PEt 3 ) 3 IrCl and unreacted [(C 8 H 14 ) 2 IrCl] 2 is observed. On heating to 80 °C, the above mixture leads to the iridium(III) dihydride (PEt 3 ) 3 IrH 2 Cl. The source of the hydride ligands is not clearly established.

Reactivity of Triazaphospholes and Phosphenium Kations with Diazadienes and α Diketones

Abstract We previously reported that 1 (R=Ph, Me) reacts faster with 3 (R′= Ph, npr) than the α diketones, leading mainly to spirocompounds. The first step of there action of diazadiene with-1 involves an attack of the nitrogen atom lone pair on phosphorus.