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In the rotational spectrum of ethylene oxide, the five lowest-lying vibrational states are assigned and the vibration-rotation constants and the centrifugal distortion constants are derived. The vibrational frequencies are estimated from relative intensity measurements at νa=803±18 cm−1 and νb=814±23 cm−1 for the antisymmetric species (with respect to the C2 operation) and at νc=872±34 cm−1, νd=1020±33 cm−1, and νe=1109±42 cm−1 for the symmetric species. The intensity measurements of the remaining spectral lines showed that these lines belong to vibrational states at frequencies above about 1000 cm−1. The νa, νb, and νc states are tentatively assigned to ν15, ν12, and ν5, respectively, by taking into account the Goriolis interactions.

The microwave spectra in the ground and five low-lying vibrational states of 12C2H432S and in the ground state of 12C13CH432S and 12C2H434S have been assigned to high-J transitions. The rotational and centrifugal distortion constants were derived. Four of the five vibrational states were found to be in Coriolis interaction in pairs; one of the pairs was identified as the symmetric and antisymmetric ring deformation modes, ν5(A1) and ν12(B1), but another pair was unexplicable from any of the previously reported vibrational assignments. The infrared and Raman spectra in the liquid and gas phases were examined, and the latter pair of vibrations was interpreted as ν14(B2) at 945 cm−1 and ν8(A2) at about 970 cm−1. This novel assignment of ν8 around 970 cm−1 was based on not only the results of microwave spectroscopy, but also on the observation of an unsymmetric band contour in the infrared spectrum of the gaseous sample.

The resonance Raman spectra of some Wurster’s cation dimers were measured in alcohol solution at 201 K and in glassy matrix at 77 K. The spectra of the dimer of p-phenylenediamine cation showed the...

Resonance Raman spectrum of 1,2,4,5-tetracyanobenzene anion radical (TCNB−) was measured and compared with that of the neutral molecule (TCNB). Particularly, a Raman line assigned to C1C2 stretching vibration decreased its frequency remarkably when TCNB was converted to TCNB−. This decrease indicated that the lowest unoccupied molecular orbital (LUMO) of TCNB had a node on C1C2 bonding, showing that the LUMO belonged to an au species. Furthermore vibrational analyses of TCNB and TCNB− were carried out and the assignment of their Raman lines was confirmed.

An example of “anomalous” Raman polarization is presented by measuring the polarization dispersion of a resonant depolarized line of anthracene anion near the first absorption band. The molecular origin of the asymmetric Raman tensor is discussed on the basis of a vibronic effect associated with the resonant electronic level.

The absolute intensities of the stretching fundamentals of cyanoacetylene and cyanoacetylene-d were measured in gaseous and crystalline (77 K) states. As had been expected from the previous result for hydrogen cyanide, a striking intensity increase upon crystallization was observed not only for νCH(CD) also for the other fundamentals. The observed intensities were reduced to dipole-moment derivative with respect to the internal coordinates, ∂μ⁄∂r. Then, by taking advantage of the strictly linear geometry of hydrogen-bonded chains in the crystals, it was demonstrated that the derivative with respect to the hydrogen-bonded distance, [∂μ⁄∂rN···H], was primarily responsible for the remarkable change in ∂μ⁄∂r; this was in accordance with the previous conclusion for hydrogen cyanide. A discrepancy from this view which appeared for ∂μ⁄∂r3 was interpreted as being mainly caused by the vibronic behavior of π-electrons.

The absolute intensities of OH− and OD− stretching absorptions in Na, Ca, and K hydroxide crystals have been measured in the films formed on a quartz window. The thickness of the films was determined by chemical or flame photometric analysis of the solution in which the sample film had been dissolved. The expected difference between OH− and OD− in the dipole-moment derivative, (dμ/dr)OD–(dμ/dr)OH, was observed to be in excellent or moderate agreement with the theoretical value given from Ellison’s equation for Na and Ca. This result also proves that the polarization of dμ/dr is in the O−–H+(D+) direction in these cases. As for K hydroxides, although the numeric results are rather dubious, the intensities are apparently by far greater than the two others, confirming the hydrogen-bond formation in this crystals, as suggested by the crystal structure and vibrational frequencies.

The absolute infrared intensities of crystalline HGN and DCN were measured at the temperature of liquid N2. In comparison with the gaseous values, both stretching fundamentals (v1, v3) exhibited a striking increase in the integrated absorption, while the bending (v2) was almost unchanged. From the observed intensity change, the change in the dipole-moment derivatives with respect to the molecular internal coordinates was calculated to be ∂ΔM⁄∂rC=N=1.43 D/A and ∂ΔM⁄∂rC−H=2.01 D/A, those values were chosen from two alternative possibilities as the more probable set. The significance of these values, however, is somewhat peculiar to the optically-active crystalline vibrations, so they were then resolved into derivatives with respect to purely intramolecular and intermolecular coordinates: [∂ΔM⁄∂rC−H]=0.58 D/A and [∂ΔM⁄∂rH···N]=−1.43 D/A. The general intensity features were reasonably interpreted by considering the contribution of a charge-transfer structure to the H–N hydrogen bonding.

The resonance Raman spectra of TCNE-M+ (M=Na, K, Rb, Cs) in MTHF solutions have been measured at 100 K by exciting radiations within the long wavelength absorption band characteristic of the dimer (TCNE−)2. Two remarkably resonant lines have been observed at about 180 cm−1 and 150 cm−1, showing an obvious change of the relative intensity depending on the counter cation species. The resonance behavior definitely indicates that the stretching vibration of interradical bond is responsible for these lines. Formation of two different types of dimer salts has been proposed as the most probable interpretation of the observed spectral behaviors.

Raman and infrared spectra of nickelocene and ferrocene were studied as regards metal–ligand vibrations. It was found that the C5H5-ring tilt vibration, ν16(e1g), of nickelocene has considerably low frequency. This was discussed in view of metal–ligand binding between both metallocenes.

Resonance Raman specta have been observed for the dimer of p-benzosemiquinone anion. When the exciting-light frequency was exactly resonant with the absorption band characteristic of this dimer, a new polarized Raman line appeared at 177 cm−1 with a striking resonance enhancement. The resonant behavior and the frequency value both indicate that it can reasonably be assigned to the interradical stretching vibration of the parallel D2h dimer molecule, much as in the case of the previous Wurster’s cation dimers.

Synopsis. Polarization dispersion of the νC≡N Raman line of the N,N-dimethylaniline-TCNB complex indicated that the two CT absorption bands are assignable to different acceptor orbitals, in contrast with those of TCNE complexes.