Vibrational frequencies and structural determination of diethynyldimethylsilane

The normal mode frequencies and corresponding vibrational assignments of diethynyldimethylsilane are examined theoretically using the Gaussian 98 set of quantum chemistry codes. Each of the vibrational modes was assigned to one of nine types of motion predicted by a group theoretical analysis (Si-C stretch, C[triple bond]C stretch, C-H stretch, C[triple bond]C-H bend, Si-C[triple bond]C bend, C-Si-C bend, H-C-H bend, CH3 wag, and CH3 twist) utilizing the C3v symmetry of the molecule. A set of uniform scaling factors was derived for each type of motion. Predicted infrared and Raman intensities are reported.     

Vibrational frequencies and structural determination of triethynylmethylstannane

The normal mode frequencies and corresponding vibrational assignments of Triethynylmethylstannane (SnCH(3)(CCH)(3)) are examined theoretically using the Gaussian 98 set of quantum chemistry codes. Each of the vibrational modes was assigned to one of nine types of motion predicted by a group theoretical analysis (Sn-C stretch, C[triple bond]C stretch, C-H stretch, C[triple bond]C-H bend, Sn-C[triple bond]C bend, C-Sn-C bend, H-C-H bend, CH(3) wag, and CH(3) twist) utilizing the C(3v) symmetry of the molecule. A set of uniform scaling factors was derived for each type of motion. Predicted infrared and Raman intensities are reported.     

Vibrational frequencies and structural determination of triethynylmethylgermane

The normal mode frequencies and corresponding vibrational assignments of triethynylmethylgermane are examined theoretically using the Gaussian98 set of quantum chemistry codes. Each of the vibrational modes was assigned to one of nine types of motion predicted by a group theoretical analysis Ge-C stretch, C[triple bond]C stretch, C-H stretch, C[triple bond]C-H bend, Ge-C[triple bond]C bend, C-Ge-C bend, H-C-H bend, CH3 wag, and CH3 twist) utilizing the C3v symmetry of the molecule. Uniform scaling factors were derived for each type of motion. Predicted infrared and Raman intensities are reported.     

Vibrational frequencies and structural determinations of 1,1-dicyanocyclopropane

The vibrational frequencies and corresponding normal mode assignments of 1,1-dicyanocyclopropane are examined theoretically using the Gaussian98 set of quantum chemistry codes. All normal modes were successfully assigned to one nine types of motion predicted by a group theoretical analysis (C-H stretch, C[triple bond]N stretch, C-C stretch, C-C[triple bond]N bend, C-C-C bend, CH2 scissors, CH2 wag, CH2 rock, CH2 twist) utilizing the C2v symmetry of the molecule. The molecular orbitals of 1,1-dicyanocyclopropane are also examined.     

Vibrational frequencies and structural determinations of maleonitrile

The vibrational frequencies and corresponding normal mode assignments of maleonitrile are examined theoretically using the GAUSSIAN98 set of quantum chemistry codes. All normal modes were successfully assigned to one of eight types of motion predicted by a group theoretical analysis (C triple bond N stretch, C=C stretch, C-C stretch, C-H stretch, C-H bend, C-C triple bond N bend, C-C triple bond N bend, C-C=C-C torsion) utilizing the C(2v) symmetry of the molecule. The molecular orbitals of maleonitrile are also examined.     

Vibrational frequencies and structural determination of trimethylarsine oxide

The normal mode frequencies and corresponding vibrational assignments of trimethylarsine oxide are examined theoretically using the Gaussian 98 set of quantum chemistry codes. All normal modes were successfully assigned to one of eight types of motion (As-C stretch, As=O stretch, C-H stretch, C-As-C bend, As=O bend, H-C-H bend, CH3 wag, and CH3 twist) utilizing the C3v symmetry of the molecule. Calculations were performed at the Hartree-Fock, DFT(B3LYP), and MP2 levels of theory using the standard 6-311G** basis. Calculated infrared intensities and Raman activities are reported.     

Vibrational frequencies and structural determination of phosphorous tricyanide

The normal mode frequencies and corresponding vibrational assignments of phosphorous tricyanide (P(CN)(3)) are examined theoretically using the Gaussian98 set of quantum chemistry codes. Each of the vibrational modes was assigned to one of four types of motion predicted by a group theoretical analysis P-C stretch, CN stretch, P-C[triple bond]C bend, and C-P-C bend) utilizing the C(3v) symmetry of the molecule. A uniform scaling factor was derived for each type of motion. Predicted infrared and Raman intensities are reported.     

Reaction dynamics and vibrational spectroscopy of CH3D molecules with both C-H and C-D stretches excited

State-resolved reactions of CH3D molecules containing both C-H and C-D stretching excitation with Cl atoms provide new vibrational spectroscopy and probe the consumption and disposal of vibrational energy in the reactions. The vibrational action spectra have three different components, the combination of the C-H symmetric stretch and the C-D stretch (nu1 + nu2), the combination of the C-D stretch and the C-H antisymmetric stretch (nu2 + nu4), and the combination of the C-D stretch and the first overtone of the CH3 bend (nu2 + 2nu5). The simulation for the previously unanalyzed (nu2 + nu4) state yields a band center of nu0 = 5215.3 cm(-1), rotational constants of A = 5.223 cm(-1) and B = 3.803 cm(-1), and a Coriolis coupling constant of zeta = 0.084. The reaction dynamics largely follow a spectator picture in which the surviving bond retains its initial vibrational excitation. In at least 80% of the reactive encounters of vibrationally excited CH3D with Cl, cleavage of the C-H bond produces CH2D radicals with an excited C-D stretch, and cleavage of the C-D bond produces CH3 radicals with an excited C-H stretch. Deviations from the spectator picture seem to reflect mixing in the initially prepared eigenstates and, possibly, collisional coupling during the reaction.     

Vibrationally controlled chemistry: mode- and bond-selected reaction of CH3D with Cl

Selective vibrational excitation controls the competition between C-H and C-D bond cleavage in the reaction of CH(3)D with Cl, which forms either HCl + CH(2)D or DCl + CH(3). The reaction of CH(3)D molecules with the first overtone of the C-D stretch (2nu(2)) excited selectively breaks the C-D bond, producing CH(3) exclusively. In contrast, excitation of either the symmetric C-H stretch (nu(1)), the antisymmetric C-H stretch (nu(4)), or a combination of antisymmetric stretch and CH(3) umbrella bend (nu(4) + nu(3)) causes the reaction to cleave only a C-H bond to produce solely CH(2)D. Initial preparation of C-H stretching vibrations with different couplings to the reaction coordinate changes the rate of the H-atom abstraction reaction. Excitation of the symmetric C-H stretch (nu(1)) of CH(3)D accelerates the H-atom abstraction reaction 7 times more than excitation of the antisymmetric C-H stretch (nu(4)) even though the two lie within 80 cm(-1) of the same energy. Ab initio calculations and a simple theoretical model help identify the dynamics behind the observed mode selectivity.     

Vibrational frequencies and structural determination of tetrafluoroformaldazine

The normal mode frequencies and corresponding vibrational assignments of tetrafluoroformaldazine (F(2)CNNCF(2)) are examined theoretically using the Gaussian98 set of quantum chemistry codes. Each of the vibrational modes was assigned to one of nine types of motion predicted by a group theoretical analysis (C-F stretch, C[triple bond]N stretch, N-N stretch, C=C-N bend, CF(2) wag, CF(2) rock CF(2) scissors, CF(2) twist, and C=N-N=C torsion) utilizing the C(2h) symmetry of the molecule. Uniform scaling factors was derived for each type of motion. Predicted infrared and Raman intensities are reported.     

Vibrational frequencies and structural determination of 1,6-dicarba-closo-hexaborane(6)

The normal mode frequencies and corresponding vibrational assignments of 1,6-dicarba-closo-hexaborane(6) are examined theoretically using the GAUSSIAN98 set of quantum chemistry codes. All normal modes were successfully assigned to one of six types of motion predicted by a group theoretical analysis (B-B stretch, B-C stretch, B-H stretch, C-H stretch, B-H bend, and C-H bend) utilizing the D(4h) symmetry of the molecule. The vibrational modes of the naturally isotopically substituted (1-(10)B, 2-(10)B 3-(10)B, and 4-(10)B) forms of 1,6-dicarba-closo-hexaborane(6) were also calculated and compared against experimental data. A complex pattern of frequency shifts and splittings is revealed.     

Vibrational frequencies and structural determination of dicyanodifluorosulfur

The normal mode frequencies and corresponding vibrational assignments of dicyanodifluorosulfur are examined theoretically using the Gaussian03 set of quantum chemistry codes. Each of the vibrational modes was assigned to one of six types of motion predicted by a group theoretical analysis (CN stretch, SC stretch, SF stretch, FSC bend, SCN bend, and CSC bend) utilizing the C(2v) symmetry of the molecule. A set of uniform scaling factors was derived for each type of motion. Predicted infrared and Raman intensities are reported.     

Vibrational frequencies and structural determination of 1,3-dichloro-1,3-diazetidine-2,4-dione

The normal mode frequencies and corresponding vibrational assignments of 1,3-dichloro-1,3-diazetidine-2,4-dione are examined theoretically using the Gaussian 98 set of quantum chemistry codes. Each of the vibrational modes was assigned to one of six types of motion predicted by a group theoretical analysis (C=O stretch, N-C stretch, N-Cl stretch, N-C-N bend, N-Cl bend, and C=O bend) utilizing the C2h symmetry of the molecule. Uniform scaling factors was derived for each type of motion. Predicted infrared and Raman intensities are reported.     

Vibrational frequencies and structural determination of tetraethynylstannane

The normal mode frequencies and corresponding vibrational assignments of Sn(CCH)₄ are examined theoretically using the 98 set of quantum chemistry codes. Each of the vibrational modes was assigned to one of six types of motion predicted by a group theoretical analysis (Sn–C stretch, CC stretch, C–H stretch, CC–H bend, Sn–CC bend, and C–Sn–C bend) utilizing the T_d symmetry of the molecule. A set of uniform scaling factors were derived for each type of motion. Predicted infrared and Raman intensities are reported.     

Vibrational frequencies and structural determination of digermyl ether

The normal mode frequencies and corresponding vibrational assignments of digermyl ether in C(2v) symmetry are examined theoretically using the Gaussian 98 set of quantum chemistry codes. All normal modes were successfully assigned to one of six types of motion (Ge-H stretch, Ge-O stretch, Ge-O-Ge bend, H-Ge-H bend, GeH(3) wag, and GeH(3) twist) predicted by a group theoretical analysis. By comparing the vibrational frequencies with IR and Raman spectra available in the literature, a set of scaling factors is derived. Predicted infrared and Raman intensities are reported.     

Vibrational frequencies and structural determinations of 1,5-dicarba-closo-pentaborane(5)

The normal mode frequencies and corresponding vibrational assignments of 1,5-dicarba-closo-pentaborane(5) are examined theoretically using the GAUSSIAN 98 set of quantum chemistry codes. All normal modes were successfully assigned to one of six types of motion predicted by a group theoretical analysis (C-H stretch, B-H stretch, B-B stretch, B-C stretch, C-H wag, and B-H wag) utilizing the D(3h) symmetry of the molecule. By comparing the vibrational frequencies with IR and Raman spectra available in the literature, a set of scaling factors is derived. Theoretical IR and Raman intensities are reported.     

Vibrational frequencies and structural determination of trichloroboroxine

The normal mode frequencies and corresponding vibrational assignments of trichloroboroxine (B3O3Cl3) in D3h symmetry are examined theoretically using the Gaussian 98 set of quantum chemistry codes. All normal modes were successfully assigned to one of five types of motion (B-Cl stretch, B-O stretch, B-Cl bend, O-B-O bend, and B(OOCl) umbrella motion) predicted by a group theoretical analysis. By comparing the vibrational frequencies with IR and Raman spectra available in the literature, a set of scaling factors is derived. Molecular orbitals and bonding are examined.     

Vibrational frequencies and structural determination of dewar benzene

The vibrational frequencies and corresponding normal mode assignments of dewar benzene are examined theoretically using the 98 set of quantum chemistry codes. All normal modes were successfully assigned to one of six types of motion predicted by a group theoretical analysis (C–H stretch, C–C stretch, C=C stretch, CH wag, C–C–C bend, and C–C–C–C torsion) utilizing the C_2v symmetry of the molecule. The molecular orbitals and bonding of dewar benzene are examined. Predicted normal mode frequencies for trans-dewar benzene (C_2h symmetry) are presented.     

Vibrational frequencies and structural determinations of tetraisocyanatosilane

The normal mode frequencies and corresponding vibrational assignments of Si(NCO)(4) are examined theoretically using the GAUSSIAN 98 set of quantum chemistry codes. Each of the vibrational modes was assigned to one of six types of motion predicted by a group theoretical analysis (Si-N stretch, N-C-O symmetric stretch, N-C-O asymmetric stretch, N-C-O bend, Si-N-C bend, and N-Si-N bend) utilizing the T(d) symmetry of the molecule. Uniform scaling factors were derived for each type of motion. Predicted infrared and Raman intensities are reported.