M. T. Boisdon

Formation of stable cyclic dicoordinated phosphorus compounds by reaction of cyclophosphazanes with lewis acids

Abstract Thermal equilibrium between dicoordinated and tricoordinated phosphorus compounds (i.e. benzodiazaphosphole ⇄cyclotetraphosphazane) has been observed. The dicoordinated compounds have been stabilized by complexing with Lewis acid and isolated.

Composes du phosphore dicoordonne: Reaction de diaza-1,4 dienes-1,3 disubstitues sur les derives de diazaphosphole. Du triazaphosphole-1,2,4,3 et de precurseurs de composes du phosphore dicoordonne

Addition of diazadienes 5 to dicoordinated phosphorus derivatives such as triazaphospholes 1 or diazaphospholes 3 leads to new tetracoordinated phosphorus spirocompounds 2 or 4. The tricoordinated phosphorus species 7 and 9 exist in a monomer tetramer PIII equilibrium but only the monomeric PII form reacts with diazadienes 5 leading to the spirocompounds 8 and 10. The monomers of 7 and 9 stabilized by complexation react with 5 to afford spirocompounds analogous to 2 and 4. In all these reactions the dicoordinated phosphorus atom is a good electrophile.

Vibrational study of 2(1H)-pyridinone (2-pyridone) in H2O and 1-d-2(1H)-pyridinone (2-pyridone ND) in D2O

Abstract A complete assignment is proposed for the infrared and Raman spectra of the solutions of 2(1H)-pyridinone (2-pyridone)(NHP) in H2O and 1- d -2(1H)-pyridinone (2-pyridone ND) (NDP) in D2O. From Raman polarisation data, NDP high deuteriation ratio, dilution and temperature effects, the following points are discussed: ND/NH isotopic shifts, assignment of some modes, associations by hydrogen bond. For NHP solutions in H2O, the ν NH and ν CO are respectively less, and more, perturbed than for the centrosymmetrical dimer of NHP in CHCl3.

A FOURIER TRANSFORM INFRARED SPECTROSCOPIC STUDY OF YEAST HEXOKINASE : CONFORMATIONAL CHANGES UNDER INTERACTION WITH SUBSTRATES AND INHIBITORS

Abstract The infrared (FTIR) spectroscopy study of several complexes of yeast hexokinase with substrates and inhibitors allows the determination of open and closed conformations of the protein. The analysis is based on a correlation between FTIR and X-ray data for one of the inhibitor–enzyme complexes of the study and from that reference, the features of the amide I band hydration component.

2(1H)-pyridinone (2-pyridone): self-association and association with water. Spectral and structural characteristics: infrared study and ab initio calculations.

DFT calculations of 2(1H)-pyridinone (2-pyridone NHP), the centrosymmetric dimer (NHP)2 and the closed complexes (NHP, H2O) and (NHP, 2H2O), with their deuterated homologues NDP, (NDP)2, (NDP, D2O) and (NDP, 2D2O), are compared with vibrational spectra of NHP and NDP in ternary mixtures CH3CN, NHP, H2O. Experimental data are also obtained for NHP or NDP in various solvents. The protic solvent effects demonstrate that mechanical couplings are different in the 1500-1700 cm(-1) range for the nuC=O and nu8b (valence of the ring) modes in NHP and NDP (or (NHP, H2O) and (NDP, D2O)). For the first time, data are obtained for NDP in the dimer (NHP, NDP). Comparison of data for pyridone, monomer, dimer or complexed with water, shows that in the complexes, water is a weaker proton acceptor and a stronger proton donor than a second pyridone molecule in the centrosymmetric dimer.

Equilibre Ester Phosphorique, Hydroxyphosphorane Role des Liaisons Hydrogene, Acidite de Bronsted

A phosphoric ester elaborated from two butyltartrate moeities exists in solution as phosphoric ester because of intramolecular hydrogen bonds. In presence of triethylamine, it turns into the triethylammonium salt of its isomeric hydroxyspirophosphorane. Its pKa has been determined by titrimetry followed by potentiometry, in solution in DMF or (and) DMSO. Its values (7.4 and 4.4 respectively) correspond to an acid more dissociated than carboxylic acids. All these results have been rationalized by semiempiric quantic calculations.

Assignment of the vibrational spectra of 2(1H)-pyridinone (2-pyridone) in the solid state, and in solution as centrosymmetrical dimer. Comparison with 1-methyl-2(1H)-pyridinone (N-methyl-2-pyridone)☆

Abstract The complete assignment of the vibrational spectra of 2(1H)-pyridinone (2-pyridone), 1-D-2(1H)-pyridinone (2-pyridone ND) and 1-methyl-2(1H)-pyridinone (N-methyl-2-pyridone) is obtained from a comparative analysis of their IR and Raman spectra (condensed phase and molar solutions in CHCl3 or CDCl3). For the 2-pyridone centrosymmetrical dimer, the strength of the NH…O hydrogen bond association is discussed. Comparison is made with the recent work of Medhi and of Nowak et al.