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.

ABSTRACT

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(µ2-I)2Cu}(µ2-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(µ2-I)2Cu}(µ4-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(µ4-I)(µ2-I)Cu}2(µ4-L1)]n (CP3), in which [Cu(µ4-I)(µ2-I)Cu]n ribbons are interconnected through µ4-bridging L1 ligands. Upon the reaction of L1 with CuBr in a 1 2 ratio, a 2D CP [{Cu(µ2-Br)}2(µ2-L1)(µ4-L1)0.5]n (CP4) is formed at room temperature and a 2D CP [{Cu(µ2-Br)}2(µ4-L1)]n (CP5) is obtained in refluxing propionitrile. In CP4 and CP5 Cu atoms are bridged by a single µ2-Br ligand giving rise to [Cu(µ2-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(µ2-Br)}3(MeCN)(µ4-L1)]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(µ2-Cl)2Cu}(µ4-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 [(HgI2)(µ2-L1)]n (CP8) and the linear 1D ribbons of CP9 and CP12 [(HgX2)(µ2-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(µ2-Br)2HgBr}(µ2-L1)] (CP10) is produced. HgI2 and HgBr2 have also been reacted with 2-methyl-1,3-dithiane L2 yielding the molecular complexes [{IHg(µ2-I)2HgI}(κ1-L2)2] (D1) and [HgBr2(κ1-L2)2] (M1). Two heterometallic 1D materials [{IHg(µ2-I)2HgI(µ2-I)2{Cu(RCN)2}2(µ2-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)(µ2-L1)1.5]n (CP15).