Abstract
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 ηcoordinated 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 ηtype. 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.
Highlights
Macrocyclic multidentate Lewis acids or anticrowns1 represent a novel class of anion receptors and catalysts
The water species in 3 are η3coordinated 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
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
Summary
Macrocyclic multidentate Lewis acids or anticrowns represent a novel class of anion receptors and catalysts (see reviews references 2–8 and references cited in recent papers references 9–17). Owing to the presence of several Lewis acidic centres in the macrocyclic chain of anticrowns, these charge-reversed analogues of crown ethers and related species are able to bind cooperatively various anions and neutral Lewis bases with the formation of complexes of unique structures. Interesting is complex 2 which was isolated from the reaction of 1 with aqueous [18]crown-6 in dry CH2Cl2 in 79% yield. In this complex, each water species is cooperatively bound through the oxygen atom by three Hg sites of the adjacent anticrown whereas both its protons form H-bonds with the oxygen atoms of [18]crown-6. We report the results of our study on the complexation of macrocycle 1 with [15]crown-5 as well as the data on the self-assembly of unique supramolecular aggregates in the interaction of 1 with aqueous [18]crown-6 in methanol and acetone as solvents
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