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W-S stretching modes

The strongest band at 378 cm" in the infrared spectrum of [WeSgCpylel has been assigned to the W—S stretching mode of the... [Pg.55]

More complete assignment of the M—S stretching modes in M[S2C2(CN)2]3 2 (M = V, Mo, W) requires parallel far-IR studies and/or metal isotope shift data, which are not available for the Mo and W complexes. Far-IR spectroelectrochemical studies of V[S2C2(CN)2]3 2- revealed redox... [Pg.232]

Figure 25. Resonance Raman spectra of dithionite-reduced P.furiosus (a) FOR and ib) AOR in the W—S stretching region. The spectra were recorded using 488-nm excitation for samples ( 3 mM) in 50 mM Tris buffer, pH 7.8, frozen at 25 K. Bands marked with an asterisk correspond to lattice modes of ice. A linear ramp has been subtracted to correct for a sloping fluorescence background. Figure 25. Resonance Raman spectra of dithionite-reduced P.furiosus (a) FOR and ib) AOR in the W—S stretching region. The spectra were recorded using 488-nm excitation for samples ( 3 mM) in 50 mM Tris buffer, pH 7.8, frozen at 25 K. Bands marked with an asterisk correspond to lattice modes of ice. A linear ramp has been subtracted to correct for a sloping fluorescence background.
The Fermi resonance Hamiltonian consists of two terms. The first one, Ho, is the Dunham expansion, which characterizes the uncoupled system, while the second term, Hp, is the Fermi resonance coupling, which describes the energy flow between the reactive mode and one perpendicular mode. For the three systems, HCP CPH, HOCl HO - - Cl and HOBr HO + Br, the reactive degree of freedom is the slow component of the Fermi pair and will therefore be labeled s, while the fast component will be labeled /. Thus, the resonance condition writes co/ w 2c0s. More explicitly, for HCP the slow reactive mode is the bend (mode 2) and the fast one is the CP stretch (mode 3), while for HOCl and HOBr the slow mode is the OX stretch (X = Cl,Br) (mode 3) and the fast one is the bend (mode 2). The third, uncoupled mode— that is, the CH stretch (mode 1) for HCP and the OH stretch (mode 1) for HOCl and HOBr—will be labeled u. With these notations, the Dunham expansion writes in the form... [Pg.287]

As a second example of the use of character tables in the analysis of IR and Raman spectra, we turn to BCI3 with Dj symmetry. Because it has four atoms, we expect six vibrational modes, three of which will be stretching modes (because there are three bonds) and three of which w/U be bending modes. Table 3.5 shows the derivation of r , for the molecule s twelve degrees of freedom. Application of the reduction equation and subtraction of the translational and rotational representations gives... [Pg.46]

Table 4 Assignment of vibration modes in the spectral range 2,000-3,800 cm. The intensity is classified as very strong (vs), strong (s), medium (m) and weak (w). The symbol Vg signifies a symmetric stretching mode and Vag signifies an antisymmetric stretching mode, respectively. Table 4 Assignment of vibration modes in the spectral range 2,000-3,800 cm. The intensity is classified as very strong (vs), strong (s), medium (m) and weak (w). The symbol Vg signifies a symmetric stretching mode and Vag signifies an antisymmetric stretching mode, respectively.
Figure 1 The normal modes of motion for the three stretch modes of DCCH. (Adapted from T. A. Holme and R. D. Levine, Chem. Phys. Lett. 150 393 (1988).) The displacement of the atoms in each mode is shown by an arrow. Note that while all atoms contribute to all modes, the respective contributions do vary and the v, mode is almost a localized CH stretch. For recent studies of the overtone spectroscopy of HCCH and its isotopomers see J. Lievin, M. Abbouti Temsamani, P. Gaspard, and M. Herman, Chem. Phys. Lett. 190 419 (1995) M. J. Bramley, S. Carter, N. C. Handy, and 1. M. Mills, J. Mol. Spectrosc. 160 181 (1993) B. C. Smith and J. S. Winn, J. Chem. Phys. 89 4638 (1988) K. Yamanouchi, N. Ikeda, S. Tuschiya, D. M. Jonas, J. K. Lundberg, G. W. Abramson, and R. W. Field, J. Chem. Phys. 95 6330 (1991).)... Figure 1 The normal modes of motion for the three stretch modes of DCCH. (Adapted from T. A. Holme and R. D. Levine, Chem. Phys. Lett. 150 393 (1988).) The displacement of the atoms in each mode is shown by an arrow. Note that while all atoms contribute to all modes, the respective contributions do vary and the v, mode is almost a localized CH stretch. For recent studies of the overtone spectroscopy of HCCH and its isotopomers see J. Lievin, M. Abbouti Temsamani, P. Gaspard, and M. Herman, Chem. Phys. Lett. 190 419 (1995) M. J. Bramley, S. Carter, N. C. Handy, and 1. M. Mills, J. Mol. Spectrosc. 160 181 (1993) B. C. Smith and J. S. Winn, J. Chem. Phys. 89 4638 (1988) K. Yamanouchi, N. Ikeda, S. Tuschiya, D. M. Jonas, J. K. Lundberg, G. W. Abramson, and R. W. Field, J. Chem. Phys. 95 6330 (1991).)...
WeSg unit. The second bond at 231 cm" is attributed with some uncertainty to another set of Tj modes involving either W—W or W—N stretching or W—S bending vibrations 43). [Pg.55]

Wolkenstein s bond polarizability approach to Raman intensities has been applied to the terminal carbonal stretching vibrations of M(CO)g (M = Cr, Mo, or W) and the general intensity formulae given. The model is valuable in providing an insight as to why the totally symmetric stretching modes of metal carbonyls and their derivatives frequently give rise to weak bands in the Raman effect. ... [Pg.122]

In recent years Nakamoto (W) has pioneered in the use of Isotopes of the transition metals in order to make assignments of the vibrational bands of their complexes. ISy studying the spectra of °Cr(acac)s and Cr(acac)3, Nakamoto, Udovlch, and Takemoto ( ) were able to assign a band at h60 cm" to a Cr-0 stretching mode and one at 592 cm" to an out-of-plane ring mode. On the basis of 0 - isotopic substitution, the 592... [Pg.37]


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S Mode

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