The infra-red spectra of pyrimidine-d0 and -d4 have been measured between 4000 and 300 cm−1 in gas, liquid and solid phases. Since the analysis of the rotational band envelopes alone was not sufficient for a definite assignment, useful information was gained from the interpretation of the crystal spectra in polarized light of both isotopic species.
A relation of the form, f = 34·4/r5·97 mdyn/Å, (f = stretching force constant; r = bond length) based on accurately known data has been obtained for NO bonds.
Infrared and Raman data were used to assign the vibrational spectrum of trimethyl phosphite. The assignment was aided by comparison of the infrared and Raman data for trimethyl phosphite with the known infrared and Raman data and assignments for phosphorous triflouride and trimethyl phosphate.
The infra-red spectra of 1,2-, 1,3-, 1,4-, 1,5-, 1,6-, 1,7-, and 1,8-diaza-, 1,3,4-, 1,3,5-, 1,3,6-, 1,3,7-, 1,3,8-, 1,4,5- and 1,4,6-triaza-, and 1,4,5,8-tetraazanaphthalene, and the Raman spectrum of 1,5-diazanaphthalene, have been determined and correlated. Band assignments for 1,4,5,8-tetraaza- and 1,5-diaza-naphthalene are discussed in relation to those for naphthalene.
Infrared spectra of several enamino ketones containing the structural unit OCCCN(Alk)2 have been examined and the band splitting occurring in a number of spectra was shown to be due to rotational isomerism. The νCO frequency of one of the conformational isomers shows an abnormal spectral behaviour moving upwards under the action of methanol and heavy water. It was established by means of solvent shift measurements that the CO and CC stretching vibrations are strongly coupled. The limitations of the applicability of Bellamys solvent method of assigning characteristic frequencies are discussed.
The assignments of the fundamental frequencies of 1,3,5-trithiane for the region 3000-250 cm−1 are made, mainly from analogies with 1,3,5-trioxane. The infra-red spectra of addition dcompounds, C3H6S3.HgX2 and C3H6S3.AgX, where X = Cl, Br or I, and C3H6S3.AgBF4.H2O, C3H6S3.AgNO3.H2O and C3H6S3.AgNO3, recorded as mulls in Nujol and hexachlorobutadiene, are described and their structural significance is discussed.
Fatty acids undergo self-association and form 1:1 molecular complexes with pyridine on mixing the ingredients in the low dielectric solvent carbon tetrachloride. Infra-red spectroscopic studies of the pyridine—fatty acid—carbon tetrachloride system confirm the existence of a tautomeric equilibrium involving the ion-paired and non-ion-paired associated complexes in the solution as is represented below:
Gas phase band intensities of v3 and v4 of SiCl4, GeCl4 and SnCl4 have been derived from dispersion curves measured using a Michelson interferometer in the range 1000 to 10 cm−1. The results obtained are discussed in relation to the corresponding liquid phase band intensities. Bond polar properties are derived from the observed intensities using a modified Gribov method, the moments obtained being 0.9 D for SiCl, 1.5 D for GeCl and 2.7 D for SnCl.
The infrared spectra of the ten isomeric dimethyl naphthalenes and the two monomethyl naphthalenes have been observed in the CH stretch, 2000-1650 and the 700-400 cm−1 regions. The effect on the aromatic CH stretching vibrations due to the position of the methyl groups on the naphthalene nucleus is outlined. The position of the methyl groups can be established from data obtained from the 2000-1650 and the 700-400 cm−1 regions. Effect on band frequencies and intensities by replacement of methyl by phenyl group in the monosubstituted naphthalene is discussed.
The Raman spectra of B-trihalogenoborazines are reported, together with a normal co-ordinate analysis of their totally symmetric vibrational modes. The results provide information on the effect of B atom substituents on the electron density distribution in the six-membered BN ring. Spectral trends in the series B3H3N3H3, B3F3N3H3, B3Cl3N3H3, B3Br3N3H3, B3I3N3H3 are correlated with the way in which force constants and forms of the normal coordinates are affected by the substituents.
The nuclear magnetic resonance spectra of aqueous solutions of three β-hydroxy carboxylic acids and some of their derivatives were measured as a function of the pH. The chemical shifts of the methylene hydrogens, adjacent to the carboxyl group, exhibit titration curves. The chemical shift between the two methylene hydrogens behaves differently in each compound, the most common behaviour being the occurrence of a minimum in the shift at pH ⋍ pK. The value of the spin—spin coupling constant changes only very slightly with the pH. The effect of added neutral salts and the variation of the temperature were also investigated in some of the acids. Qualitative conclusions concerning inter- and intramolecular hydrogen bonds and electrostatic interactions in these molecules were derived from the results.
This work describes an electronic theory, based on L.C.A.O., of the integrated intensities of localized vibrators in π-electron systems.
A general method for quantitative spectrochemical analysis is presented. In this method the powdered sample is mixed with a great excess of buffer material and pressed into a briquette. The briquette is placed in the cup of the sample electrode and arced with a direct current of 10 Amp. The buffer is composed of 12% LiF and 88% graphite by weight. The total sample concentrations used in the briquettes are 1% 0.1%, 0.01%, so principal and trace elements can be analysed. The minimum amount of sample needed 0is 1.5 mg. The method can be used for a great diversity of sample materials. Results are presented for a number of BCS and NBS standard samples.
We have analysed the ultra-violet absorption spectrum of azoxybenzene into component bands. This analysis has enabled us to propose a new interpretation of the electronic transitions of azoxybenzene, which partially differs from those of earlier authors.
Charge transfer complexes of iodine with nicotinamide and nicotinnitrile have been studied spectrophotometrically. An isobestic point occurring at 467 mμ and 474 mμ in the iodine amide and iodine nitrile systems have been observed. The λmax for the two system of complexes is found to be at 414 mμ and 428 mμ respectively in the blue shifted band of the iodine. Out of the two sites for the interaction, the nitrogen atom of the pyridine nucleus has been considered to be the site for interaction.
For several primary and secondary alkansulphonylchlorides, the integral absorption of the asymmetric and symmetric SO2-stretching vibration and of the CS-stretching vibrations caused by rotational inversion, were estimated by the method of Wilson and Wells. In the case of the primary homologues for these vibrations the integral absorption decreases with the length of the chain and changes linearly with the logarithm of the velocity constants of hydrolysis. A linear relationship also exists between the integral absorption and the corresponding Taft-constants.
Evidence for the formation of complexes between fumaronitrile and iodine monochloride is given by NMR, infra-red and visible absorption spectra.
