THE INFRARED AND THE NEAR-ULTRAVIOLET ABSORPTION SPECTRA OF POLYPHENYL DERIVATIVES OF THE ELEMENTS OF GROUPS IVb AND Vb

The near-ultraviolet absorption spectra of polyphenyl derivatives of the IVb and Vb elements have been studied in detail. In the case of the triphenyl derivatives of the Vb elements, the unshared p-electrons on the central atoms interact strongly with the π-orbitals of the benzene rings. When the central atoms do not possess unshared electrons as in the case of the derivatives of the IVb and the pentavalent Vb elements, there appears to be no such resonance interaction. The Hammett reactivity constants of the para- and meta-trityl, triphenylsilyl, and triphenylgermanyl groups are estimated to be close to zero. However, the reactivity constant of the triphenylsilyl group in the para position of phenol is estimated to be about 0.30. The infrared spectra of the phenyl derivatives of the IVb and Vb elements show smooth trends due to mass effects of the central atoms, in the C=C skeletal, C—H out-of-plane, and other vibrations. The absorption frequencies which are assigned to the phosphorus-phenyl and silicon–phenyl bonds in the literature do not appear to be unique for these linkages.

ULTRAVIOLET ABSORPTION SPECTRA AND ACIDITIES OF ISOMERIC THIATRIAZOLE AND TETRAZOLE DERIVATIVES

The ultraviolet absorption spectra of 5-(substituted)amino-1,2,3,4-thiatriazoles and the corresponding isomeric 1-substituted-tetrazoline-5-thiones have been studied. The spectra and the dipole moments of the 5-(substituted)amino-1,2,3,4-thiatriazoles eliminate the possibility of meso-ionic structures for these compounds. The dipole moments of 5-amino-, 5-methylamino-, and 5-dimethylamino-1,2,3,4-thiatriazole were all high but approximately of the same value (5.77 to 5.84 D). This suggests that the amino thiatriazoles are best represented by conventional covalent structures with significant ionic resonance contributions. The thiatriazole ring system exhibits a characteristic absorption maximum at 250–255 mμ and an electron-withdrawing effect approximately equal to the tetrazolyl ring system. The tetrazolinethionolyl ring system is similarly electron-withdrawing. The relative acidities of the 1-substituted-tetrazoline-5-thiones and the 5-alkylmercaptotetrazoles have also been studied and the results support the observations made on the basis of their ultraviolet absorption spectra.

ISOMERIC 5-(SUBSTITUTED)AMINOTHIATRIAZOLE AND 1-SUBSTITUTED-TETRAZOLINETHIONES

The reaction of organic isothiocyanates with sodium azide in ethanol and water has been investigated. Water is shown to be the more advantageous solvent for this reaction giving higher yields and initially purer 1-substituted-tetrazoline-5-thiones. A series of these latter compounds was made by this procedure. The yield of product appears to be dependent on the electrical properties of the substituent of the isothiocyanate, the yields decreasing as the electron-donating properties increase. A series of new 4-substituted-thiosemicarbazides has been prepared and converted by diazotization to the corresponding 5-(substituted)aminothiatriazoles. A theory to account for the differences in the mode of reaction of hydrazoic acid and azide ion is presented and discussed. The basic conversion of 5-(substituted)aminothiatriazoles to 1-substituted-tetrazolinethiones may involve a simple dearrangement–rearrangement mechanism complicated by side reactions. A summary of known isomeric 5-(substituted)aminothiatriazoles and 1-substituted-tetrazolinethiones is presented.

THE INFRARED SPECTRA OF 4-SUBSTITUTED-THIOSEMICARBAZIDES AND DIAZOTIZATION PRODUCTS

The infrared absorption spectra of 4-substituted-thiosemicarbazides, 5-(substituted)amino-1,2,3,4-thiatriazoles, and the corresponding isomeric tetrazolinethiones have been studied and structural assignments of importance to these systems made or suggested. Important conclusions drawn from the spectral data are: there is no suggestion of any thiol–thione tautomerism for the solid 4-substituted-thiosemicarbazides and that the thione structure predominates for these substances; that the so-called 5-thiol-tetrazoles also exist as thiones; and that the diazotization products of the 4-substituted-thiosemicarbazides yield 1,2,3,4,-thiatriazoles rather than the isomeric open chain thiocarbamyl azides. The C==S, —N—C==S, and cyclic —N—N==N— configurational assignments, which are of importance to the classes of compounds studied, are discussed.