Certain types of unsaturated lactones exhibit two bands in the region of the spectrum associated with the C=O stretching vibrational mode. This is observed both in the infrared and Raman spectra.The infrared spectra of 23 simple saturated and unsaturated lactotles have been examined in an attempt t o determine the structural features with which this carbonyl band splitting is associated. I t appears to be common to most unsaturated five-and six-membered ring lactones in which the double bond is conjugated with the carbonyl group, though one well-established exception has been observed. The relative intensities of the two bands are extremely sensitive to changes in the polarity of the solvent; they also vary reversibly with temperature but are indepenaent of concentration.The s~l i t t i n a of the C=O stretchina band is attributed to an intramolecular vibrational effect similar 'to that which occurs i' n cyclopentanone and in certain Az-cyclopentenone derivatives. Its possible dependence on Fermi resonance with the overtone of a lower lying fundamental vibration is discussed.Similar effects occur in other types of carbonyl compounds, such as benzoyl chloride and cyclic five-membered ring anhydrides, and care is needed to distinguish carbonyl band splitting of this kind from that associated with equilibria between conformational isomers.

The structure of zinc chloride complexes with different ratios of chloride to zinc, formed in concentrated ZnCl2 aqueous solutions, were determined from large-angle X-ray scattering using concentrations of the chloride complexes estimated by complementary Raman spectroscopic measurements. The highest chloro complex, [ZnCl4]2-, is tetrahedral with a Zn-Cl bond length of 2.294(4) Å. The trichloro complex, [ZnCl3]-, which coordinates one water molecule, is pyramidal with the Cl-Zn-Cl angle 111°. The Zn-Cl and the Zn-H2O bonds are 2.282(4) and 1.9 Å, respectively. The two lower complexes, [ZnCl2] and [ZnCl]+ , cannot be separated by Raman spectra. The average Zn-Cl distance in these complexes is 2.24 Å, and the average Zn-H2O distance is 1.9 Å. In [Zn(H2O)6]2+ the Zn-H2O distance is 2.15 Å.

Vibration amplitudes and electron-deformation densities, Ap, have been determined for KZnF3 from diffraction data measured using focused synchrotron radiation with A=0.7000(2) A at the Photon Factory, KEK, Japan. The lack of systematic variation of intensity with path length indicates that secondary extinction is not significant, a result confirmed when the strong intensities measured using a weaker parallel beam with A = 0.5000 (2).~ showed no dependence on A. The 0.7 A study is generally concordant with, but more precise (R = 0.008, wR = 0.006) than earlier analyses with Mo Ka radiation. The charge of +0.47 (4)e determined for the Zn atom is larger than that calculated with extinction corrections which minimize differences between observed and calculated structure factors. Near the Zn nucleus Ap is mildly anisotropic, with a topography similar to that found for closed-shell atoms in related perovskite structures.

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An optical absorption study has been made of trapped electrons produced in -irradiated organic-mixture glasses at 77 K. Electronic spectra were observed for trapped electrons in a variety of binary-mixture glasses which consist of solvents with various polarity. Optical parameters obtained from the observed spectra are reported. The spectra of trapped electrons have the only one absorption maximum in all of the mixture glasses studied except for 2-propanol-3-methylpentane glass. The absorption maximum in the spectrum of trapped electrons in a mixed solvent is located at a wavelength between those in pure component solvents, the wavelength depending on the mixture composition. There are two absorption maxima in the spectrum of trapped electrons in 2-propanol-3-methylpentane glass, each maximum corresponding to that in its component spectrum. Changes in the trappedelectron spectra with composition of the mixtures are interpreted in terms of the polarity and structure effects.