Zeeman effect on 127I and 35Cl NQR of ICl 2AlCl 4 and two modifications of I 3AlCl 4

Abstract

The 127I and 35Cl NQR spectra of ICl 2AlCl 4, α-I 3AlCl 4 and β-I 3AlCl 4 were observed, and the Zeeman effect on the single crystals of these compounds was examined mainly on the polyhalogen cations at room temperature. The asymmetry parameters ( η) for the central iodine atoms of the IX 2 + cations were 0.154, 0.373, and 0.336 in ICl 2AlCl 4, α- and β-I 3AlCl 4, respectively. The η-values for the terminal chlorine atoms in the ICl 2 + ion were ca. 0.16, whereas those for the terminal iodine atoms in the I 3 + cation of each modification were 0.06 on the average. The bond angles of the V-shaped I 3 + cations were estimated to be 104.2 and 103.3° in α- and β-I 3AlCl 4, respectively, from the directions of the electric field gradients (efg). The net charges on the polyhalogen cations were calculated to be +0.85, +0.99 and +1.04 in ICl 2AlCl 4, α- and β-I 3AlCl 4, respectively.