A ³⁵Cl NQR Study on Cs₂[AU^ICl₂] [Au^IIICl₄]

Abstract

When the temperature was increased from 77 K, the resonance lines became gradually weak without changing AV q and immeasurable above 215 K. ESR spectra taken at various temperatures revealed the presence of paramagnetic sites of ca. 5x 10 2<) mol -1 arising from Au(II). The small but finite concentration of Au(II) or some other reason should be responsible for the fade out phenomenon and the large Avq observed.

35Cl Quadrupole Relaxation Study on Cs2[Au(I)Cl2][Au(III)Cl4] and Cs2[Ag(I)Cl2][Au(III)Cl4]

“…These values are in good agreement with those already reported [3 -5] [2]. A similar but much weaker resonance line was observed for II, showing a one order of magnitude lower Au(II) concentration.…”

“…[1]. In a previous paper [2], we reported that tetragonally distorted perovskite type Cs 2 [Au(I)Cl 2 ][Au(III)Cl 4 ] polycrystals yielded two 35 Cl NQR lines, Q1 = 17.28 and Q2 = 27.10 MHz at 77 K, in accordance with the crystal structure, I4/mmm [3 -5]. These signals were assigned to the two kinds of Cl atoms in the crystal: Q1 to Cl-Au(I) and Q2 to Cl-Au(III).…”

“…The sample I showed the 35 Cl resonance Q1 = 17.28 MHz for Au(I)-Cl and Q2 = 27.10 MHz for Au(III)-Cl at 77 K [2]. The sample II yielded the same resonance frequencies as I, whereas III showed a singlet frequency Q2 Table 1).…”

“…However, there were two experimental evidences [2], possibly caused by the charge transfer effect: 1. the NQR lines 1Q and 2Q showed ten times larger width than those usually observed in the single valence Au(III) complexes [6]. 2.…”

“…Therefore we have undertaken further ∆ and 1Q measurements on the same compound, but prepared in a different manner [2], because the Au(II) concentration is expected to depend on the method of preparation. Cs 2 spectrometer [7] was used for the observation of 35 Cl NQR. The line shape of the resonances was determined by monitoring the spin echo amplitude dependence on the rf frequencies.…”