Formation of Dinuclear, Macrocyclic, and Chain Structures from HgI₂ and a Semirigid Benzimidazole-Based Bridging Ligand:  An Example of Ring-Opening Supramolecular Isomerism

Abstract

The reactions of HgI(2) with the semirigid ditopic ligand 1,3-bis(benzimidazol-1-ylmethyl)-2,4,6-trimethylbenzene (bbimms) afforded three new complexes, [Hg(2)(mu-I)(2)I(2)(bbimms)] (1), [Hg(2)I(4)(bbimms)(2)] (2), and catena-poly[HgI(2)(bbimms)] (3). The ligand and all complexes have been structurally characterized by single-crystal X-ray diffraction. 1 is a triply bridged dinuclear complex comprised of two Hg(II) ions, one bridging ligand, two bridging I(-) anions, and two terminal I(-) anions. 2 is a dinuclear metallamacrocycle comprised of two Hg(II) ions, two bridging ligands, and four terminal I(-) anions, while 3 is a helical chain with the repeating unit of HgI(2)(bbimms). 2 and 3 can be classified as supramolecular isomers, and both are related to the triply bridged precursor 1 via the addition of one more ligand in a ring-opening process.

Structure of the mercury(II) mixed-halide (Br/Cl) complex of 2,2′-(5-tert-butyl-1,3-phenylene)bis(1-pentyl-1H-benzo[d]imidazole)

“…A literature survey of mercury halide complexes with benzimidazole derivatives has shown that they come in two main types: polymeric, bridging either through the halide (Zhang et al, 2015;Li et al, 2007;Shen et al, 2005) or through alternative N atoms from the benzimidazole moieties (Xiao et ISSN 2056-9890 al., 2009Huang et al, 2006;Li et al, 2007Li et al, , 2012aDey et al, 2013;Du et al, 2011;Chen et al, 2013;Su et al, 2003;Xu et al, 2011), or as discrete molecules (i.e. non-polymeric).…”

First Report on Crystal Engineering of Hg(II) Halides with Fully Substituted 3,4-Pyridinedicarboxamides: Generation of Two-Dimensional Coordination Polymers and Linear Zig-Zag Chains of Mercury Metal Ions

“…Though Hg···Hg distance as short as 3.41Å has never been reported but many halide bridged Hg based structures, with ubiquitous Hg 2 X 2 bridges are known to have Hg···Hg inetarctions within this range. [133][134][135][136][137][138][139][140] However, compounds with these interactions leading to linear metal chains are rather rare. Lu et al, 141 (Table 2) parallel to the a axis.…”

Metallacycles or coexistence of isomeric metallacycle and chain: Anion-dependent luminescent Ag complexes of a flexible diaminotriazine–imidazole ligand

“…Ring-opening isomerism is of much current interest. Several cases have shown that reversible ring-opening of macrocyclic complexes with labile metal centers can occur in solution, and then the crystallization process can yield either the metallacycle or polymer form (often chain), which may be determined by template effects involving solvent or guest molecules, or by secondary bonding involving counterions [49][50][51][52][53][54][55][56]. However, there are remarkably few cases showing cocrystal structures of metallacycle and chain isomers [57,58].…”