Coordination Chemistry of Anticrowns. Isolation of the Chloride Complex of the Four-Mercury Anticrown {[(o,o′‑C₆F₄C₆F₄Hg)₄]Cl}⁻ from the Reaction of o,o′‑Dilithiooctafluorobiphenyl with HgCl₂ and Its Transformations to the Free Anticrown and the Complexes with o‑Xylene, Acetonitrile, and Acetone

The paper reports that the interaction of o,o′-dilithiooctafluorobiphenyl with HgCl₂ in ether results in the formation of the lithium chloride complex Li­{[(o,o′-C₆F₄C₆F₄Hg)₄]­Cl} (11) of the four-mercury anticrown (o,o′-C₆F₄C₆F₄Hg)₄ (12) along with the earlier isolated and characterized three-mercury anticrown (o,o′-C₆F₄C₆F₄Hg)₃ (2). The complex was identified by the reaction with 12-crown-4 and determination of the structure of the [Li­(12-crown-4)₂]­{[(o,o′-C₆F₄C₆F₄Hg)₄]­Cl} (13) formed. According to an X-ray analysis, the chloride anion in 13 is simultaneously coordinated with all four Hg centers of the anticrown, forming with them a pyramidal Hg₄Cl fragment. The reaction of 11 (in the form of an acetonitrile solvate, 11·nMeCN) with boiling water leads to removal of LiCl from 11 and to the formation of free anticrown 12, the subsequent recrystallization of which from o-xylene affords the o-xylene complex {[(o,o′-C₆F₄C₆F₄Hg)₄]­(o-Me₂C₆H₄)₂} (14). The obtained 14 forms in the crystal infinite chains consisting of alternating anticrown units and bridging o-xylene moieties. Another o-xylene molecule in each macrocyclic fragment of the chain plays the role of a terminal ligand. In both cases, the o-xylene ligands in 14 are bonded to only one Hg center of the corresponding mercuramacrocycle. The back-conversion of complex 14 into 12 and o-xylene proceeds in the course of its thermal decomposition under vacuum at 100–120 °C. The reaction of 12 with acetonitrile yields the nitrile complex {[(o,o′-C₆F₄C₆F₄Hg)₄]­(MeCN)₂} (15), which also forms infinite polymeric chains in the crystal. In each monomeric unit of the chain, the corresponding bridging nitrile is bonded to only one mercury atom of the anticrown moiety, whereas the other nitrile ligand is coordinated with two Hg sites. The synthesis and structure of the complex {[(o,o′-C₆F₄C₆F₄Hg)₄]­(Me₂CO)₂(H₂O)} (16), containing two acetone and one water ligand per molecule of 12, are also reported. Each acetone molecule in 16 interacts with only one Hg atom of 12, while the water molecule is coordinated with two mercury centers and, in addition, forms H-bonds with the oxygen atoms of the acetone species.