Dicarboxylate assisted synthesis of the monoclinic heterometallic tetrathiocyanato bridged copper(II) and mercury(II) coordination polymer {Cu[Hg(SCN)4]}n: Synthesis, structural, vibration, luminescence, EPR studies and DFT calculations

The synthesis of the monoclinic polymorph of {Cu[Hg(SCN)4]}n is reported. The compound, as determined by X-ray diffraction of a twinned crystal, consists of mercury and copper atoms linked by μ1,3-SCN bridges. The crystal packing shows a highly porous infinite 3D structure. Diagnostic resonances for the SCN– ligand and metal–ligand bonds in the IR, far-IR and Raman spectra are assigned and discussed. The electronic band structure along with density of states (DOS) calculated by the DFT method indicates that the compound is an indirect band gap semiconductor. The DFT calculations show that the observed luminescence of the compound arises mainly from an excited LLCT state with small MLCT contributions (from the copper to unoccupied π⁎ orbital of the thiocyanate groups). The X-band EPR spectrum of the powdered sample at room temperature reveals an axial signal with anisotropic g factors consistent with the unpaired electron of Cu(II) ion in the dx2−y2 orbital.

Synthesis and X-ray structure determination of the monoclinic {Cu[Hg(SCN)4]}n is reported. The IR, far-IR, Raman, photoluminescence as well as EPR spectra of the compound is discussed. Also, the emission and semiconducting behavior of the compound is illustrated through the density functional theory calculation of electronic band structure along with density of states.Figure optionsDownload as PowerPoint slideResearch highlights
► The monoclinic {Cu[Hg(SCN)4]}n has been prepared.
► The structure of the compound is determined by XRD of a twinned crystal.
► The IR, far-IR, Raman, EPR and emission spectra of the compound is investigated.
► As shown by DFT calculations, the emission bands of the compound are mainly LLCT.
► Small MLCT from the copper to the thiocyanate groups contributes to these bands.