Crystal structure of the Hg4SiS6 and Hg4SiSe6 compounds

The crystal structures of Hg4SiS6 and Hg4SiSe6 compounds were investigated using X-ray powder diffraction. These compounds crystallize in the monoclinic Cc space group with the lattice parameters a=1.23020(5), b=0.71031(4), c=1.22791(4) nm, β=109.721(3) deg. for Hg4SiS6 and a=1.28110(4), b=0.74034(4), c=1.27471(1) nm, β=109.605(3) deg. for Hg4SiSe6. Atomic parameters were refined in the isotropic approximation (RI=0.0571 and RI=0.0555 for the Hg4SiS6 and Hg4SiSe6, respectively)