2-Bromo-2-methyl-N-(4-nitro­phen­yl)propanamide

The title compound, C10H11BrN2O3, exhibits a small twist between the amide residue and benzene ring [the C—N—C—C torsion angle = 12.7 (4)°]. The crystal structure is stabilized by weak N—H⋯O, C—H⋯Br and C—H⋯O inter­actions. These lead to supra­molecular layers in the bc plane

The nuclear electric quadrupole moment of hafnium from the molecular method

The molecular method is used to obtain nuclear electric quadrupole moment (NQM) values for hafnium through electric field gradients (EFGs) at this nucleus in HfO and HfS. Dirac-Coulomb calculations with the Coupled Cluster approach, DC-CCSD (T) and DC-CCSD-T, were carried out to achieve the most accurate estimates of these EFGs. Higher order corrections are also added. Hence, the most reliable values for 177Hf and 179Hf determined here are 3319(33) and 3750(37) mbarn, respectively, in nice accordance with the best currently accepted NQMs for this element. (C) 2012 Elsevier B.V. All rights reserved.FAPESP (Brazilian agency)Brazilian agency FAPESPCNP

The Infrared Fundamental Intensities And Polar Tensor Of Ch3nc.

The molecular force field and polar tensor of methyl isocyanide have been determined from its gas phase vibrational frequencies and infrared intensities. Quantum chemical results from MP2(FC), B3LYP and quadratic configuration interaction calculation including single and double substitutions procedures using a 6-311 + +G(3d,3p) basis set have been used to determine the signs of the dipole moment derivatives with respect to the normal coordinates as well as estimate individual fundamental intensities of the overlapped v1-v5 and v3-v6 band systems. Principal component graphical representations of the A1 and E symmetry polar tensor elements were useful in determining preferred sets of tensor elements. The mean dipole moment derivative (GAPT charge) of the methyl carbon in CH3NC, 0.347 e, is between the corresponding values in CH3CN, 0.110 e, and CH3F, 0.541 e. The mean dipole moment derivatives obtained here indicate the correct 1s methyl carbon ionization energy as 293.35 eV which is 0.98 eV higher than the corresponding ionization energy of the terminal atom.5937-4

The Infrared Fundamental Intensities And Polar Tensor Of Cf4.

Atomic polar tensors of carbon tetrafluoride are calculated from experimental fundamental infrared intensities measured by several research groups. Quantum chemical calculations using a 6-311 + + G(3d, 3p) basis set at the Hartree-Fock, Möller-Plesset 2 and Density Functional Theory (B3LYP) levels are used to resolve the sign ambiguities of the dipole moment derivatives. The resulting carbon mean dipole moment derivative, pC = 2.051 e, is in excellent agreement with values estimated by a MP2/6-311 + + G(3d, 3p) theoretical calculation, 2.040 e, and by an empirical electronegativity model, 2.016 e. The pC value determined here is also in excellent agreement with the one obtained from the CF4 1s carbon ionization energy using a simple potential model, 2.059 e. Crawford's G intensity sum rule applied to the fundamental intensities of CH4, CH3F, CH2F2 and CHF3 results in a prediction of a 1249 km mol(-1) intensity sum for CF4 in good agreement with the experimental values of 1328 +/- 37.9, 1208.0 +/- 54.4 and 1194.8 +/- 7.4 km mol(-1) reported in the literature.56A1329-3

Qtaim Charge-charge Flux-dipole Flux Interpretation Of Electronegativity And Potential Models Of The Fluorochloromethane Mean Dipole Moment Derivatives.

Infrared fundamental vibrational intensities and quantum theory atoms in molecules (QTAIM) charge-charge flux-dipole flux (CCFDF) contributions to the polar tensors of the fluorochloromethanes have been calculated at the QCISD/cc-pVTZ level. A root-mean-square error of 20.0 km mol(-1) has been found compared to an experimental error estimate of 14.4 and 21.1 km mol(-1) for MP2/6-311++G(3d,3p) results. The errors in the QCISD polar tensor elements and mean dipole moment derivatives are 0.059 e when compared with the experimental values. Both theoretical levels provide results showing that the dynamical charge and dipole fluxes provide significant contributions to the mean dipole moment derivatives and tend to be of opposite signs canceling one another. Although the experimental mean dipole moment derivative values suggest that all the fluorochloromethane molecules have electronic structures consistent with a simple electronegativity model with transferable atomic charges for their terminal atoms, the QTAIM/CCFDF models confirm this only for the fluoromethanes. Whereas the fluorine atom does not suffer a saturation effect in its capacity to drain electronic charge from carbon atoms that are attached to other fluorine and chlorine atoms, the zero flux electronic charge of the chlorine atom depends on the number and kind of the other substituent atoms. Both the QTAIM carbon charges (r = 0.990) and mean dipole moment derivatives (r = 0.996) are found to obey Siegbahn's potential model for carbon 1s electron ionization energies at the QCISD/cc-pVTZ level. The latter is a consequence of the carbon mean derivatives obeying the electronegativity model and not necessarily to their similarities with atomic charges. Atomic dipole contributions to the neighboring atom electrostatic potentials of the fluorochloromethanes are found to be of comparable size to the atomic charge contributions and increase the accuracy of Siegbahn's model for the QTAIM charge model results. Substitution effects of the hydrogen, fluorine, and chlorine atoms on the charge and dipole flux QTAIM contributions are found to be additive for the mean dipole derivatives of the fluorochloromethanes.11512572-8