2,2′-Ethylenebis(1,3-dithiane) as a polydentate μ2-, μ4- and μ5-assembling ligand for the construction of sulphur-rich Cu(I), Hg(II) and heterometallic Cu(I)/Hg(II) coordination polymers featuring uncommon network architectures

With the aim to elaborate novel and inexpensive sulphur-rich materials featuring unusual network architectures, the coordination chemistry of the tetradentate thiaheterocycle 1,2-di(1,3-dithian-2-yl)ethane L1 ligand toward CuX and HgX2 salts was investigated. When L1 is reacted with CuI in a 1:1 ratio, a two-dimensional CP [{Cu(mu(2)-I)(2)Cu}(mu(2)-L1)](n) (CP1) is formed, in which two out of four S atoms of L1 remain non-coordinated. Upon treatment of L1 with CuI in a 1: 2 ratio, [{Cu(mu(2)-I)(2)Cu}(mu(4)-L1)](n), (CP2) is obtained, in which each S atom of L1 coordinates to one copper centre forming a 2D layer. Raising the ligand-to-CuI ratio to 1:4 affords the 2D material [{Cu(mu(4)-I)(mu(2)-I)Cu}(2)(mu 4-L1)](n) (CP3), in which (Cu(mu(4)-I)(mu(2)-I)Cu](n) ribbons are interconnected through mu(4)-bridging L1 ligands. Upon the reaction of L1 with CuBr in a 1: 2 ratio, a 2D CP [{Cu(mu(2)-Br))(2)(mu(2)-L1)(mu(4)-L1)(0.5)](n) (CP4) is formed at room temperature and a 2D CP [{Cu(mu(2)-Br)}(2)(mu(4)-L1)](n) (CP5) is obtained in reftuxing propionitrile. In CP4 and CP5 Cu atoms are bridged by a single mu(2)-Br ligand giving rise to [Cu(mu(2)-Br)Cu](n) ribbons but CP4 differs from CP5 from the metal to ligand ratio and the presence of non-coordinated S atoms. Employing a 1: 3 ratio, a 1D ribbon [{Cu(mu(2)-Br)}(3)(MeCN) (mu(4)-1)](n) (CP6) is generated, that contains both tetrahedral and trigonal copper atoms. CP6 also presents two different L1 ligands that differ by the coordination mode of the sulphur atoms (S acting as 2 or as 4 electron-donor). With CuCl, a 2D network [{Cu(mu(2)-Cl)(2)Cu)(mu(4)-L1)](n) (CP7) is generated. L1 coordinates also on HgX2 salts to yield CPs whose architecture depends on the ligand-to-metal ratio. The meander-shaped 1D CP [(HgI)(2)/(mu(2)-L1)](n) (CP8) and the linear 1D ribbons of CP9 and CP12 [(HgX2)(mu(2)-L1)](n) (X = Br, Cl) result from treatment with L1 in a 1 : 1 ratio. In the case of HgBr2, using a 2 :1 metal-to-ligand ratio, 1D polymeric [(BrHg(mu(2)-Br)(2)HgBr}(mu(2)-L1)] (CP10) is produced. HgI2 and HgBr2 have also been reacted with 2-methyl-1,3-dithiane L2 yielding the molecular complexes [{IHg(mu(2)-I)(2)Hgl}(kappa(1)-L2)(2)] (D1) and [HgBr2(kappa(1)-L2)(2)] (M1). Two heterometallic 1D materials [{IHg(mu(2)-I)(2)HgI(mu(2)-I)(2){Cu(RCN)(2)}(2)(mu(2)-L1)](n) (CP13) and (CP14) result from the treatment of CP1 with HgI2 in MeCN or EtCN. Performing the reaction of CP1 with HgBr2 in acetonitrile produces the zwitterionic 2D material [Cu(MeCN)}(HgIBr2)(mu(2)-L1)1.5](n) (CP15).