Knowledge Bank

The asymmetry parameters of the electric field gradients at the chlorine nuclei in the tetrachlorides of carbon, silicon, germanium and tin have been determined from an analysis of the residual line shape as a function of a static magnetic field applied to a polycrystalline sample. For each compound the lowest frequency resonance was used for the study. Because of the high multiplicity of resonances in $CCl4$ only an upper limit can be given for the asymmetry parameter. The line shapes were measured from zero static field up to the limit where the line was broadened beyond detection or to the point of interference from the absorption of another sideband of the superregenerative oscillator used for the measurements. The asymmetry parameters found were: . These relatively large asymmetry parameters are due to an unbalance in the $\pi$-bonding to the chlorine atom. The unbalance can arise from either unsymmetrical use of d-orbitals in intramolecular bonding or from large amounts of inter-molecular bonding. The relative contributions of these two factors will be discussed.