Theoretical study on the activation of C-H bond in ethane by PdX (X = F, Cl, Br, H, and CH) in the gas phase.

The mechanism of C-H bond activation of ethane was catalyzed by palladium halide cations (PdX (X = F, Cl, Br, H, and CH)), which was investigated using density functional theory (DFT) at B3LYP level. The reaction mechanism was taken into account in triplet and singlet spin state potential energy surfaces. For PdF, PdCl, and PdBr, the high spin states were the ground states, whereas the ground states were the low spin states in PdH and PdCH.

Study of the competitive mechanisms of cyclohexane dehydrogenation by gas-phase Ni2(+) cationic dimer: one-face dehydrogenation versus flip dehydrogenation.

The mechanism of cyclohexane dehydrogenation catalyzed by the cationic dimer Ni2 (+) has been investigated at the B3LYP level of density functional theory. The first dehydrogenation occurs readily (it is exothermic by 30 kcal/mol), whereas the second and third dehydrogenations show weaker exothermicity than the first (23 and 21 kcal/mol, respectively). These three hydrogenations corresponding to the total dehydrogenation of one face of cyclohexane mainly proceed in the doublet state due to the presence of significant minimum-energy crossing points (MECPs).

Mechanism of the palladium-catalyzed hydrothiolation of alkynes to thioethers: a DFT study.

The mechanisms of the palladium-catalyzed hydrothiolation of alkynes with thiols were investigated using density functional theory at the B3LYP/6-31G(d, p) (SDD for Pd) level. Solvent effects on these reactions were explored using the polarizable continuum model (PCM) for the solvent tetrahydrofuran (THF). Markovnikov-type vinyl sulfides or cis-configured anti-Markovnikov-type products were formed by three possible pathways.

Density functional study of S(N) 2 substitution reactions for CH(3) Cl + CX(1) X(2•-) (X(1) X(2) = HH, HF, HCl, HBr, HI, FF, ClCl, BrBr, and II).

A systematic investigation on the S(N) 2 displacement reactions of nine carbene radical anions toward the substrate CH(3) Cl has been theoretically carried out using the popular density functional theory functional BHandHLYP level with different basis sets 6-31+G (d, p)/relativistic effective core potential (RECP), 6-311++G (d, p)/RECP, and aug-cc-pVTZ/RECP. The studied models are CX(1) X(2•-) + CH(3) Cl → X(2) X(1) CH(3) C(•) + Cl(-) , with CX(1) X(2•-) = CH(2) (•-) , CHF(•-) , CHCl(•-) , CHBr(•-) , CHI(•-) , CF(2) (•-) , CCl(2) (•-) , CBr(2) (•-) , and CI(2) (•-) . The main results are proposed as follows: (a) Based on natural bond orbital (NBO), proton affinity (PA), and ionization energy (IE) analysis, reactant CH(2) (•-) should be a strongest base among the anion-containing species (CX(1) X(2•-) ) and so more favorable nucleophile.

CH4 activation by W atom in the gas phase: a case of two-state reactivity process.

Gas-phase methane activation by tungsten (W) atoms was studied at the density functional level of theory using the hybrid exchange correlation functional B3LYP. Four reaction profiles corresponding to the septet, quintet, triplet, and singlet multiplicities were investigated in order to ascertain the presence of some spin inversion during the methane activation. Methane activation mediated by W atoms was found to be a spin-forbidden process resulting from the crossing among the multistate energetic profiles.

[Study on the fluorescence spectra of LaL3 with DNA].

A fluorescence method is presented for the determination of DNA. The method is based on the interaction of LaL3 [L = morin (2', 3, 4', 5, 7-Pentahydroxyflavone), 2'-OH group deprotonated] with DNA in NH3 x H2O-NH4Cl buffer of pH = 8.0, with lambdaex at 387 nm, and lambdaem at 535 nm.