Experimental and theoretical investigations of the nuclear quadrupole resonance of ¹²⁷I in orthoperiodic acid, H<inf>5</inf>IO<inf>6</inf>

Pure nuclear quadrupole resonance of 127I in H5IO6 has been reported to occur at 44.976 MHz (m = ± 3 2⇌m = ± 1 2 transition) and 83.960 MHz (m = ± 5 2⇌ m = ± 3 2 transition) at 296 K (ref. 1). Using an externally quenched frequency modulated super regenerative spectrometer Zeeman studies have been performed at 296 K on single crystals of H5IO6 growm from aqueous solution by observation of the ± sol3 2⇌± 1 2 transition. The zero-splitting locus method has been employed for the determination of the EFG parameters. The data show that there are two physically inequivalent sites, having average asymmetry parameters, η, of 0.25, located in the unit cell. The maximum field gradient is found to lie along the short bond I-O(2) as suggested by Rama Rao and Weiss (ref. 1). The EFG parameters obtained by detailed molecular orbital calculations (CNDO/2 and INDO method) are compared with the experimental results. © 1983.