The 35C1 NQR spectra of 2,4,4,6-tetrachloro-3,5-dimethyl-cyclohexadiene-2,5-one-l and 2,4,4,6tetrachloro-cyclohexadiene-2,5-one-l were studied from 77 K up to the decomposition temperature, their crystal structure having been determined by single crystal X-ray diffraction. The first com­ pound crystallizes in the monoclinic space group C2h-P2!/m with two molecules in the unit cell. The lattice ...

In zero-field NMR [ 1.21, a sample is subjected to a time-dependent magnetic field which cycles between a high value, Bo, and zero field. The B. field is useful for preparation and high-sensitivity detection of the spins. Evolution occurs for a variable time tl in zero field. This yields sharp crystal-like NMR spectra from polycrystalline samples, where ordinarily only powder patterns are obser...

Some nitrogen-containing heterocycles can form both anionic (with abstraction of the N -H proton) and cationic derivatives (with addition of the proton to the pyridinic nitrogen atom). These include, in par­ ticular, 3,5-dichloro-l,2,4-triazole and 4,5-dichloro-2methylimidazole. These compounds were studied by 35C1 NQR spectroscopy [1,2]. Quantum-chemical analyses of the electronic structure of...