Mercury Thiolato Complexes: Syntheses, Crystal Structures, and Decomposition Pathways

Abstract

Complexes of the general formula ClHgSR (R = benzyl, neopentyl, isopropyl) and the mercury bis(thiolate) compound [Hg(SBz)2]∞ each have been prepared and characterized by single crystal X-ray diffraction. ClHgSBz·TMEDA crystallizes in the triclinic space group P1̄ with cell constants a = 8.136(2) Å, b = 9.958(7) Å, c = 11.834(3) Å, α = 108.71(2)°, β = 92.93(2)°, γ = 109.05(2)°, and Z = 2. Refinement of 2534 observed reflections yields R = 0.050 and Rw = 0.056. [ClHgS-iso-Pr]∞ crystallizes in the monoclinic space group C2 with cell constants a = 21.430(7) Å, b = 4.678(2) Å, c = 6.724(2) Å, β = 90.43(2)°, and Z = 2. Refinement of 528 observed reflections yields R = 0.039 and Rw = 0.033. [ClHg(S-neo-Pent)·0.5Py]∞ crystallizes in the monoclinic space group C2 with cell constants a = 16.732(2) Å, b = 11.200(1) Å, c = 11.929(2) Å, β = 104.21(1)°, and Z = 4. Refinement of 2561 observed reflections yields R = 0.035 and wR2 = 0.081. [Hg(SBz)2]∞ crystallizes in the monoclinic space group C2/c with cell constants a = 22.599(4) Å, b = 4.334(1) Å, c = 29.566(5) Å, β = 106.76(1)°, and Z = 8. Refinement of 1264 observed reflections yields R = 0.036 and wR2 = 0.116. The solid-state thermal decompositions of the chloromercury thiolate compounds have been studied and the XRPD patterns of the resultant solid-state materials were obtained. The formation of Hg2Cl2 is observed upon thermolysis of [ClHg(S-neo-Pent)·0.5 Py]∞ or [ClHgS-iso-Pr]∞ at 200 °C, whereas ClHgSBz·TMEDA produces HgS under identical conditions. Upon mixing equimolar quantities of HgCl2 and Ph3CSH in EtOH, moderately crystalline HgS is produced at ambient temperature. The volatile products liberated during the thermal decomposition have been isolated and characterized by GC/MS techniques. For the cases involving the production of HgS from ClHgSR (R = Bz, Ph3C), the reaction coproduct was identified as RCl. In the instances where Hg2Cl2 was synthesized from ClHgSR (R = iso-Pr, neo-Pent), R−(S)n−R (n = 2, 3, 4) have been identified. The decomposition pathways of the various chloromercurythiolate compounds are discussed, and mechanisms consistent with the observed reaction products are presented.