Crystal structures of two methylmercury complexes with 1-methylimidazoline-2-thione

Abstract

[CH3Hg(C4H6N2S)]NO3 belongs to space group [Formula: see text], a = 7.146(2), b = 7.783(3), c = 10.184(5) Å, α = 72.95(3), β = 71.09(3), γ = 81.83(2)°, and Z = 2. The structure was refined to R = 0.039 (1850 nonzero reflections). The crystal contains complex cations in which the CH3Hg+ ion is bonded to the exocyclic sulfur atom by a Hg—S bond of 2.382(2) Å. The nitrate ions form secondary bonds to mercury and hydrogen bonds to the acidic proton attached to N(3). [CH3Hg(C4H5N2S)] is monoclinic, space group Cc, a = 7.734(1), b = 17.125(3), c = 6.061(3) Å, β = 99.66(3)°, and Z = 4. Refinement converged to R = 0.039 (678 nonzero reflections). The crystal consists of individual monomeric molecules in which the CH3Hg+ ion forms a Hg—S bond of 2.338(7) Å. The molecular packing is considered as unusual, since Hg forms no intermolecular secondary bonds in the equatorial plane, even though N(3) has an available lone pair. This lone pair on N(3) is completely free, owing to the absence of H-bond donors in the structure. The applicability of HSAB theory to the present results (S- versus N-binding) is considered.