Coordination chemistry of mercury-containing anticrowns. Self-assembly of unusual supramolecular aggregates in the interaction of the three-mercury anticrown (o-C6F4Hg)3 with crown ethers in the presence of neutral monodentate oxygenous Lewis bases

The interaction of the three-mercury anticrown (o-C6F4Hg)(3) 1 with a large excess of aqueous [15]crown-5 results in the formation of a complex, {[(o-C6F4Hg)(3)]([15]crown-5)(H2O)(2)} 3, having a polydecker sandwich structure in the crystal. Every double-decker sandwich fragment of this supramolecular aggregate contains one crown ether and two water molecules in the space between the mutually parallel planes of two anticrown units. The water species in 3 are eta(3)-coordinated via the oxygen atom to the Hg centres of the neighbouring anticrown whereas both water protons are involved in the formation of H-bonds with the [15] crown-5. Each crown ether ligand in 3 forms also a weak Hg-O contact with one of the nearest molecules of 1. The reaction of 1 with aqueous [18]crown-6 in methanol leads to a self-assembly of an unusual supramolecular aggregate {[(o-C6F4Hg)(3)](2)([18]crown-6)(H2O)(2)(MeOH)(2)} 5, containing one crown ether molecule, two molecules of H2O and two molecules of methanol per two anticrown species. The crown ether and water guests in this adduct are sandwiched by two mutually parallel anticrown moieties while the methanol species are located on the free sides of the planes of the mercuramacrocycles and are coordinated with their Hg centres via the oxygen atom in an eta(3)-type. The bonding of the water species in 5 is analogous to that in 3 but the crown ether oxygen atoms form here four shortened Hg-O contacts with the anticrown units. The complex of similar composition and structure, {[(o-C6F4Hg)(3)](2)([18]crown-6)(H2O)(2)(Me2CO)(2)} 6, is produced when the interaction of 1 with aqueous [18] crown-6 is carried out in acetone as a solvent.