Bis{(4-methylthio)phenylthio}methane as assembling ligand for the construction of Cu(I) and Hg(II) coordination polymers. Crystal structures and topological (AIM) analysis of the bonding

• The tetradendate sulphur-rich ligand p-MeSC6H4SCH2SC6H4SMe-p has been synthesized.
• 1D and 2D CPs have been assembled by reaction of this tetrakisthioether with CuI, CuBr and HgBr2.
• The occurrence of unusual bent butterfly-shaped Cu(μ2-Br)2Cu clusters has been crystallographically evidenced.
• The CuI containing material exhibits strong luminescence.
• The bonding situation has been analysed by means of the Quantum Theory of Atoms in Molecules approach.

The novel 1D coordination polymer (CP) [{Cu(μ2-Br)2Cu}(μ-L2)2] CP2 has been obtained by reaction of the tetrakisthioether p-MeSC6H4SCH2SC6H4SMe-p (L2) with CuBr in a 1:2 metal-to ligand ratio. In contrast to the previously described CP [{Cu(μ2-Br)2Cu}(μ-L1)2] CP1 obtained by reaction of the tetrakisthioether p-MeOC6H4SCH2SC6H4OMe-p (L1) with CuBr, the two independent extended 1D ribbons contain bent Cu(μ2-Br)2Cu units of the butterfly-type with short Cu…Cu separations of 2.679(1) and 2.613(1) Å. In contrast to the common planar rhomboid Cu(μ2-Br)2Cu cluster, this butterfly-shaped geometry of the core is without precedent. A luminescent material of composition [(Cu4I4)(μ-L2)]nCP3 is formed by reaction of L2 with CuI in a 1:4 ratio. The two-dimensional CP of stoichiometry [Hg2Br4(L2)]nCP4 results from treatment of HgBr2 with this tetradentate thioether L2. The structure is of the adduct type with two crystallographically different covalently bound HgBr2 bars assembled in the first step into the chains through the weak Hg–S interactions involving one Hg atom and two S atoms. The chains thus constructed are further brought together through a supplementary Hg1–S1 inter-chain interactions leading to the 2D layered structure. Consequently the Hg1 atom may be considered as pentacoordinated, while the second Hg2 atom has a formal coordination number of 4. The nature of bonding in these CPs has been studied by the Quantum Theory of Atoms in Molecules(QT-AIM) approach allowing a clear classification of metal-ligand bonds and detection of π–π stacking interactions.

The 1D coordination polymer (CP) [{Cu(μ2-Br)2Cu}(μ-L2)2] CP2 has been obtained by reaction of p-MeSC6H4SCH2SC6H4SMe-p (L2) with CuBr. The two-dimensional CP of stoichiometry [Hg2Br4(L2)]nCP4 results from treatment of HgBr2 with this tetradentate ligand. The bonding situation within these materials has been analysed theoretically by means of the QT-AIM method.Figure optionsDownload as PowerPoint slide