Solid-State ¹⁹⁹Hg MAS NMR and Vibrational Spectroscopic Studies of Dimercury(I) Compounds

Abstract

The solid-state (199)Hg MAS NMR spectra of Hg(2)X(2) (X = Cl, SCN, NCO, CH(3)CO(2), CF(3)CO(2)) have been measured, and the infrared and Raman spectra of these compounds have been recorded and analyzed to further characterize them and to assist in the interpretation of the NMR data. Spinning-sideband analysis has been used to determine the (199)Hg shielding anisotropy and asymmetry parameters Deltasigma and eta from the solid-state (199)Hg MAS NMR spectra. In contrast to the case of the corresponding mercury(II) compounds, the shielding anisotropy is found to be relatively insensitive to the nature of the X group. This is consistent with the view that the electronic environment of the Hg atom in the mercury(I) compounds is dominated by the Hg-Hg bond. The changes in the (199)Hg shielding parameters from the mercury(II) to the corresponding mercury(I) compounds, as well as the changes in these parameters in the mercury(I) compounds with changes in X, can be interpreted in terms of variations in the local paramagnetic contribution to the shielding tensor.

A solid-state 199Hg NMR study of mercury halides

“…The resulting CS parameters are given in Table II. This finding is materially different from the results reported by Bowmaker et al [7,24]. The 199 Hg spin-lattice relaxation time at ambient temperature was 51 s. HgBr 2 forms a crystal with linear Br-Hg-Br structures with a space group of Cmc2 1 [2].…”

“…The 199 Hg spin-lattice relaxation time at ambient temperature is 94 s. The parameters derived from the simulation of the CS tensor are given in Table II. Whether using the data from the static sample or from the MAS experiment (Figure 8), the CS tensor of Hg 2 Cl 2 appears axially symmetric (η = 0), within experimental error, differing from the literature value of η = 0.14 obtained from an analysis of MAS data [7]. This reported value of η = 0.14 obtained from an analysis of MAS data of Hg 2 Cl 2 is quite similar to η = 0.12 for HgCl 2 [24].…”

“…MAS techniques have been previously used to measure the principal elements of the 199 Hg CS tensors of both HgCl 2 [24] and Hg 2 Cl 2 [7]. However, recent work [26] has shown that the CS tensor of HgCl 2 appears to be, within experimental error, axially symmetric (η = 0), differing from the literature value of η = 0.12 obtained from an analysis of MAS data [24].…”

“…In the solid state, the mercurous compounds are typically linear or near-linear species containing discrete metal-metal bonds of Hg 2 2+ [7]. The mercuric structures are also typically linear, though HgF 2 has a cubic CaF 2 -type structure and HgI 2 displays a diversity of structures and colors [8].…”

“…Br nuclei" [7]. However, the very large chemical-shift anisotropy in the static spectrum allows the CS tensor parameters to be extracted from the simulation.…”