Jørgen Tormod Nielsen

Hydrogen NMR spectra of pyridazine and pyrazole containing 15N

Abstract Preparation and 1H NMR spectra are described for [15N]pyridazine and [15N]-pyrazole. CNDO/2 and INDO calculations of spin-spin coupling constants are reported for pyridazine, pyrazole, pyridine, pyrrole, and thiazole. For 2JNH and 3JHH correlations between experimental and calculated data are established.

NMR studies of pyridine-N-oxide. Determination of spectroscopic constants from [15N]-, [4-2H], and the parent species

Abstract Pyridine- N -oxide, [ 15 N]pyridine- N -oxide, and [4- 2 ]pyridine- N -oxide have been investigated by NMR spectroscopy. 1 H, 2 H, and 13 C spectra have been obtained and analyzed, in terms of chemical shifts and spin-spin coupling constants. Relaxation times have been measured for 2 H and 13 C and have been used to determine the correlation time τ c under the assumption of isotropic molecular diffusion. On the basis of experimental data and observed linewidth variations the nitrogen quadrupole coupling constant has been evaluated. The experimental data are correlated with semiempirical calculations within the azine series.

1H NMR spectra of diazomethane and diazocyclopentadiene containing 15N

Abstract Preparation and 1H NMR spectra are described for [D]-, [1-15N]-, [2-15N]-diazomethane, and [1-15N]diazocyclopentadiene. CNDO/2 and INDO calculations of spin-spin coupling constants in diazomethane and diazocyclopentadiene are reported. Correlations between the calculated and experimental values are discussed.

Infrared spectra of 1,3,4-oxadiazole and 2,5,-dimethyl-1,3,4-oxadiazole. Vibrational assignment of 1,3,4-oxadiazole

Abstract The infrared absorption spectrum of 1,3,4-oxadiazole has been recorded in the region 5000-400 cm −1 in the vapor and in the liquid phases, in CS 2 and C 2 Cl 4 solutions. Also, the infrared absorption spectrum of liquid 2,5-dimethyl-1,3,4-oxadiazole was recorded in the same region. A tentative assignment of the fundamental vibrations of 1,3,4-oxadiazole is given, based on the rotational envelope contours in the vapor phase spectrum and on a comparison with the spectrum of 2,5-dimethyl-1,3,4-oxadiazole.

Vibrational spectra and fundamental frequencies of 1,2,5-oxadiazole and its deuterated species

Abstract The i.r. absorption spectra (5000–400 cm −1 ) of 1,2,5-[D]oxadiazole and 1,2,5-[D 2 ] oxadiazole have been studied. Raman spectra of the same compounds have been recorded and the Raman spectrum of 1,2,5-oxadiazole has been reinvestigated. A complete assignment of the fundamental vibrations of the deuterated 1,2,5-oxadiazoles, which fulfils the Teller-Redlich product rule and the complete isotopic rule, has been achieved. This necessitates changes in the previous assignment of v 7 and v 13 of 1,2,5-oxadiazole.

Raman spectrum and infrared crystal spectrum of1,3,4-oxadiazole vibrational assignment and thermodynamic functions of 1,3,4-oxadiazole

The Raman spectrum of liquid 1,3,4-oxadiazole has been recorded. Also, the infrared absorption spectrum of crystalline 1,3,4-oxadiazole at −196°C has been recorded in the region 4000-400 cm −1 . The tentative assignment previously published is slightly revised and the thermodynamic functions −( F 0 − H 0 0 )/ T , S 0 , ( H 0 − H 0 0 )/ T and C p 0 are calculated.

NMR studies of pyridazine-N-oxide. Determination of spectroscopic parameters from the [15N]- and parent species

Abstract Pyridazine- N -oxide and [ 15N pyridazine- N -oxide have been investigated by NMR spectroscopy. 1 H and 13 C spectra have been obtained and analyzed, in terms of chemical shifts and spin-spin coupling constants. Relaxation times have been measured for 13 C and have been used to determine the correlation time π c under the assumption of isotropic molecular diffusion. From 1 H, 15 N INDOR experiments the lineshape of N(2) is determined; analysis of the lineshape yields 1 J NN and T qN(1). On the basis of experimental data and observed linewidth variations, the N(1) nitrogen quadrupole coupling constant has been evaluated. The experimental data are correlated with semiempirical calculations within the azine series.