Metallomethane, VI [1]. Kristallstruktur von Tetrakis(chloroquecksilber)methan-Dimethylsulfoxid C(HgCl)4 · (CH3)2SO / Metallomethanes, VI [1]. Crystal Structure of Tetrakis(chloromercuri)methane-Dimethylsulfoxide C(HgCl)4 · (CH3)2SO

Abstract

The tetrakis (halomercuri) methane dimethylsulfoxide solvates C(HgX)4 · DMSO (X = Cl and Br) have been prepared. - The crystal structure of the chloro compound C(HgCl)4 · DMSO has been determined (R = 0.0611 and Rw = 0.0562). The compound crystallizes in space-group P21/n with a = 1854(1) pm, b = 727.3(5) pm, c = 1049.1(6) pm, β = 94.82(3)°, Z = 4; dc = 4.873 g·cm-3, d0 = 4.51 g-cm-3. - The C(HgCl)4 molecules have C-Hg bond lengths in the range 201.4(26) to 209.9(27) pm (average 207.0 pm), and Hg-Cl bonds between 231.4(9) and 234.2(9) pm (average 233.2 pm). The bond angles Hg-C-Hg vary from 107.3(3) to 111.7(4)° (average 109.5°), and the angles C-Hg-Cl are found within the limits 172.2(24) and 178.3(25)° (mean 174.3°). DMSO molecules (S-O bond 148.6(23)pm) are coordinated via oxygen to two Hg atoms of one C(HgCl)4 molecule and to one Hg atom of a neighbouring C(HgCl)4 molecule forming two bifurcated bridges in a dimer [C(HgCl)4 · DMSO]2; two strong Cl→···Hg and two weak S→···Hg interactions also contribute to this pair formation. The dimeric units are arranged to layers in the planes (100) and (200), such that each C(HgCl)4 molecule has six C(HgCl)4 and two DMSO molecules as neighbours; with two C(HgCl)4 molecules from each adjacent layer, each C(HgCl)4 molecule achieves a total coordination number of ten. Depending on the van der Waals radius assumed for mercury a packing coefficient 0.640 ≤ k ≤ 0.691 is obtained. - Cryoscopy and vibrational spectrometry suggest monomeric, unperturbed tetrahedral C(HgX)4 molecules in DMSO solutions.