'Chimie douce' synthesis, crystal and electronic structures of the novel Hg∼4.2Mo15X19 (X = S, Se) compounds containing Hg3, Mo6 and Mo9 clusters

The new compounds Hg similar to 4.2Mo15X19 (X=S, Se) were obtained by inserting mercury into the metastable Mo15X19 compounds at low temperature. Their crystal structures, determined from single-crystal X-ray diffraction data, show that the molybdenum-chalcogenide network is maintained through the synthesis. It consists of an equal mixture of Mo6X8X6 and Mo9X11X6 cluster units interconnected through Mo-X bonds as in the parent compounds. In both compounds, the mercury is present either as Hg2+ cations or forming linear clusters Hg-3(2+). It is the first time that the latter cluster is observed in a chalcogen environment.