Complexation of [12]Crown-4, [18]Crown-6, and 1,3,5-Trioxane with Cyclic Trimeric Perfluoro-<i>o</i>-phenylenemercury. Synthesis and Structures of the First Complexes of Crown Ethers with an Anticrown

The reaction of anhydrous [12]crown-4 with a 1:1 ethanol adduct of the three-mercury anticrown (o-C6F4Hg)3 (1) under Ar results in the formation of a double-decker sandwich complex {[(o-C6F4Hg)3]2([12]crown-4)} (4). The molecule of the crown ether in 4 is located between the mutually parallel planes of two mercury macrocycles and is coordinated to each of them through Hg−O secondary interactions. In the crown ether ligand, all four oxygen atoms are involved in the bonding to the molecules of 1, while in each anticrown species only two Hg centers take part in the coordination. If aqueous [12]crown-4 is used in the reaction with 1, the other double-decker sandwich, {[(o-C6F4Hg)3]2([12]crown-4)(H2O)2} (5), containing one crown ether molecule and two molecules of H2O in the space between the planes of the anticrown units, is produced. Every water molecule in this supramolecular aggregate is cooperatively bound through the oxygen atom by three Lewis acidic Hg sites of the neighboring anticrown, whereas one of the water protons forms the hydrogen bond with the oxygen atom of the crown ether. An additional contribution in the bonding is made by the interaction of one of the Hg centers of each anticrown unit with the nearest oxygen atom of [12]crown-4. The complex of analogous composition and close structure is formed in the reaction of 1 with aqueous [18]crown-6. However in this sandwich, {[(o-C6F4Hg)3]2([18]crown-6)(H2O)2} (6), both protons of each water species are involved in the formation of the H-bonds with the crown ether, while the bonding of each mercuramacrocycle to the crown ether is accomplished due to the coordination of two of its Hg atoms with two oxygen atoms of the crown compound. From the interaction of 1·EtOH with 1,3,5-trioxane, a 1:1 complex, {[(o-C6F4Hg)3](CH2O)3} (7), having a cage structure, has been isolated. The synthesized adducts are the first complexes of crown ethers with an anticrown.