Nuclear quadrupole resonance. Electronic structure and stereochemistry of halogenonaphthalenones

Abstract

The 35Cl NQR spectra of 2-chloro-, 2, 3-dihydro-2-bromo-2, 3-dichloro-, and 2,2,3-trichloro-4-diphenyl-methylene-1(4H)-naphthalenones (I–III) were studied. The experimental data are compared with the results from quantum-chemical calculations for the conformers of the molecules of (I–III) by the CNDO/2 method. The adequacy of the conformational description of systems (I–III) by the method using the 35Cl NQR frequencies was established by study of 1, 2-dichloroacenaphthene and 2-chlorotetrahydropyran. It was established that compound (II) in the crystal exists in the form of the conformer with the bromine atom in the axial position. The possibilities of using an electrostatic model for the discussion of the conformations of the 2, 3-dyhydro derivatives (II) and (III) with separate allowance for the geminal and vicinal environments of the chlorine probe atom are examined.