I. Infrared Studies of Hydrogen Bonding of Methanol with Aromatic Hydrocarbons. II. Infrared Spectrum and Molecular Structure of Nitrous Acid. III. Infrared Spectra and Molecular Structure of Isocyanic Acid, and Isothiocyanic Acid

Abstract

Part I of this thesis presents the results of an investigation of hydrogen bonding of methanol with aromatic hydrocarbons. The infrared spectra of methanol in various solvents indicate that the methanol molecules form weak hydrogen bonds with aromatic hydrocarbons, probably at the center of the aromatic ring. Part II of this thesis presents the results of an investigation of the infrared spectrum of nitrous acid. The spectrum indicates that there are two isomeric forms of nitrous acid, a cis and a trans form. The rotational structure of the hydrogen stretching band of the cis form indicates that the O=N-O angle of cis nitrous acid is 113 ± 2°. A normal coordinate treatment of HONO and DONO indicates that the strongest band in the spectrum out to fifteen microns is the overtone of the O=N-O bending vibration. On the basis of this treatment the frequencies of the five in plane vibrations of trans nitrous acid have been assigned as 3590, 1696, 1270, 825, and 413 cm -1 . In Part III the results of an investigation of the infrared spectrum of isocyanic acid and isothiocyanic acid are presented. For isocyanic acid the fundamental vibrational frequencies are 3534, 2280, 1340, 779, 650, and 550 cm -1 . The last frequencies were obtained from combination bands. For isothiocyanic acid the fundamental vibrational frequencies are 3530, 1972, 1000, 660, 616, and 543 cm -1 . The last three were obtained from combination bands. From the rotational structure of the N-H stretching bands of these two molecules we have calculated that the effective H-N-C angle in the ground vibrational state is 128°19' ± 40' for HNCO and 138°40' ± 1° for HNCS.