No abstract

No abstract

(N-Methyl-3-pyridinium)chlorocarbene tetrafluoroborate (MePyr(+)CCl BF4(-), 4) is generated by laser flash photolysis (LFP) of the corresponding diazirine (5) and reacted with tetramethylethylene, cyclohexene, 1-hexene, 2-ethyl-1-butene, methyl acrylate, and acrylonitrile. Absolute rate constants are measured for these carbene-alkene addition reactions, and activation parameters are obtained for additions of MePyr(+)CCl BF4(-) to tetramethylethylene, cyclohexene, and 1-hexene. MePyr(+)CCl BF4(-) is computed to be a highly reactive, electrophilic, singlet carbene, and experiments are in accord with expectations. Its activation parameters are compared with those of CF3CCl, CCl2, CClF, and CF2. In all cases, enthalpy-entropy compensation is observed, with ΔH(‡) and ΔS(‡) decreasing in tandem as carbenic stability decreases. A qualitative explanation is offered for this phenomenon.

Experimental and computational studies find that dimethylcarbene (DMC), the parent dialkylcarbene, is both predicted to be and functions as a very reactive nucleophilic carbene in addition reactions with five simple alkenes. Activation energies and enthalpies for DMC additions to 2-ethyl-1-butene and methyl acrylate are computed and observed to be negative.

The electrodepositions of Sn(II) and Sb (III) were studied in the [EMIm]BF 4 ionic liquid at ambient temperature. Linear sweep voltammetry (LSV) results indicated that the reductions of Sn(II) and Sb(III) on Pt electrode are electrochemically irreversible. The diffusion coefficients of Sn(II) and Sb(III) in the ionic liquid electrolyte were determined in terms of the LSV data. Tin and antimony ions form simpler Sn(II) chlorocomplex species and higher Sb(III) chlorocomplexes, respectively present in the ionic liquid electrolyte. Energy dispersive X-ray spectroscopy (EDX) analysis revealed that tin and antimony alloys can be electroplated in the ionic liquid electrolyte.