35Cl nuclear quadrupole resonance spectra of paradichlorobenzene as a guest molecule in clathrates formed by the werner complexes M (II)(L 4)X 2

Abstract

The 35Cl nuclear quadrupole resonance (NQR) spectra of paradichlorobenzene included in the Werner complexes M (II) (L 4)X 2 (L=4-picoline, 4-ethylpyridine, 4-vinylpyridine or 4-acetylpyridine; M (II)=Mn, Fe, Co or Ni; X − =SCN − or SeCN −) are reported. In all these complexes only one 35Cl resonance is exhibited, thus showing that there is only one type of inclusion site and that the symmetry of the site preserves the equivalence of the two chlorine atoms in PDCB. The temperature dependence of the 35Cl NQR frequency provides a measure of the degree of mobility of the guest molecule and shows that this mobility increases in the order Ni> Co> Fe> Mn and in the order 4-vinylpyridine>4-ethylpyridine>4-methylpyridine. In general, a change of anion from SCN − to SeCN − also increases the guest mobility. An independent check on the space available to the guest molecule has been obtained by measuring the unit-cell dimensions for a number of these complexes.