Chlorine nuclear quadrupole resonance in mercury chlorides and complex chlorides

Abstract

Chlorine nuclear quadrupole resonance frequencies are reported for solid compounds of known structure containing linear molecules HgCl2 and Hg2Cl2, approximately trigonal HgCl3-, and a variety of distorted octahedral forms including NH4HgCl3, CsHgCl3, and K2HgCl4,H2O. Compounds of unknown structure of the type (cation+)HgCl3, (cation+)2HgCl4, (cation+)Hg2Cl5, (cation+)2Hg9Cl20, and (cation+)4HgCl6 have also been studied. There are clear correlations between observed n.q.r. frequencies and Hg-Cl infrared stretching frequencies and bond distances. These correlations show the dependence of the degree of covalent bonding in the Hg-Cl bond with distance. The n.q.r. data confirm that many of the complex chlorides of mercury are built up by the joining of octahedral HgCl6 units, distorted in such a way as to preserve to varying extents the identity of the HgCl2 molecule. ��� Predictions of the structures are made for some complex chlorides of unknown structure, and the role of bridging in building up the compounds is discussed in terms of observed n.q.r. data for bridging chlorines.