- Structure and vibrational force field of methyldifluoroamine, CH3NF2. An electron-diffraction investigation augmented by microwave and infrared spectroscopic data and by Ab initio molecular orbital calculations
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The structure of methyldifluoroamine, CH3NF2, was determined by gas-phase electron diffraction augmented by rotational constants from microwave spectroscopy taken from the literature and by results from molecular orbital calculations. The structural results are consistent with Cs symmetry for a molecule with staggered bonds. The experimental bond distances and bond angles (rα0/rg) and 〈α), with estimated 2σ uncertainties are C-H = 1.104/1.124(5) A? (average value), N-F = 1.406/1.408(2) A?, C-N = 1.467/1.469(6) A?, C-N-F = 104.1(2)°, F-N-F = 101.7(2)°, N-C-Hanti = 109.9(11)°, N-C-Hgauche = 106.5(10)°, Hgauche-C-Hgauche = 110.6(28)°; the subscripts indicate orientation with respect to the nitrogen lone pair. A scaled quantum-mechanical (SQM) quadratic vibrational force field was evaluated by symmetrizing the quantum-mechanical (MP2/6-311++G(d,p)) Cartesian force constants and scaling the results to fit observed infrared wavenumbers from the literature. The N-F stretching force constants for the other fluoroamines NF3 and (CH3)2NF were also determined in a similar fashion. Contrary to an earlier report, the values were found to increase with decreasing bond length consistent with Badger's rule.
- Hagen, Kolbj?rn,Hedberg, Kenneth,John, Earnest Obed,Kirchmeier, Robert L.,Shreeve, Jeanne M.
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- Sequential methyl-fluorine exchange reactions of siloxide ions in the gas phase
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Exchange Me for a fluorine: Trimethylsiloxide ions in the presence of NF3 in the gas?phase undergo an unusual and sequential metathesis-type reaction wherein methyl groups are exchanged for fluorine. Theoretical calculations suggest that the reaction proceeds by a three-step internal-nucleophilic-displacement mechanism which features a pentacoordinated siliconate species (see picture) as a transition state rather than as an intermediate.
- Correra, Thiago C.,Riveros, José M.
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- Action of atomic fluorine on E- and Z-2-butene
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Irradiation of N2F4(NF2) with E- and Z-2 butene in the gas phase leads to addition of F and NF2 across the double bond in a non-stexeoselective manner and abstraction of H to give 2- butenyl radicals which interconvert rapidly before being trapped by NF2 to yield E- and Z-1- difluoroamino-2-butene and 3-difluoramino-1-butene. The configurational instability of the 2- butenyl radicals is attributed to the exothermicity of F atom abstraction. These results are contrasted with those of other workers who observed that in condensed phase reactions abstraction by t-butoxy radical leads to 2-butenyl radicals which are configurationally stable.
- Bumgardner, Carl L.,Carver, James G.
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p. 331 - 338
(2007/10/02)
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