Trimeric perfluoro-ortho-phenylene mercury (1) crystallizes from CS(2) as a pure compound. In the crystal, 1 forms staggered cofacial dimers (centroid distance of 3.38 A). In the dimer, the individual components are associated via long mercury-pi interactions (3.443 < Hg...C < 3.650 A). Interestingly, this arrangement leads to the existence of relatively short intermolecular mercury-mercury distances (3.811 < Hg...Hg < 4.093 A). In this form, compound 1 is photoluminescent and exhibits a broad emission band with a maximum at 440 nm and a shoulder at 530 nm. Compound 1 interacts with biphenyl, naphthalene, or triphenylene to form 1.biphenyl (2), 1.naphthalene (3), and 1.triphenylene (4), respectively. These adducts have been characterized by elemental analysis and X-ray crystallography. Their structure reveals the existence of stacks in which molecules of 1 and molecules of arenes alternate. In each stack, secondary pi-interactions occur between the arene and the mercury centers of 1. The resulting Hg...C distances range from 3.25 to 3.55 A and are within the sum of the van der Waals radii. They reflect the presence of secondary polyhapto-pi interactions occurring between the electron-rich aromatic molecules and the acidic mercury centers. In the case of the triphenylene adduct 4, a arene-fluoroarene interaction is also observed (centroid distance of 3.605 A). Compounds 2-4 are photoluminescent. The emission observed for 2 and 3 corresponds to the phosphorescence of the aromatic substrate and suggests the occurrence of a mercury heavy atom effect. In the case of 4, the emission appears at longer wavelengths than those typically observed for triphenylene.

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The formation of adducts involving the bidentate Lewis acid 1,2-bis(chloromercurio)tetrafluorobenzene (1) and small electron rich organic molecules has been investigated. Compound 1 does not form stable adducts with aliphatic aldehydes and can be crystallized in base-free form from acetaldehyde. The X-ray crystal structure of 1 reveals the existence of a highly cross-linked supramolecular structure in which the individual molecules are associated by Hg‚‚‚Cl and Hg‚‚‚F interactions. By contrast, 1 forms an adduct (2) with benzaldehyde. In this adduct, the benzaldehyde molecule acts as a terminal ligand and coordinates one of the mercury centers through the formation of a long Hg-O bond of 2.68(1) Å. The supramolecular structure of 2 is that of a layered compound in which the monomers are held by numerous intermolecular Hg‚‚‚Cl and Hg‚‚‚F contacts. Arene-fluoroarene interactions are also present and involve the aromatic ring of benzaldehyde, which stacks with neighboring tetrafluorophenylene units (centroid distances ) 3.58 and 3.77 Å). Interestingly, compound 1 forms chelate complexes with acetonitrile (3) and propylene oxide (4). As shown by X-ray single-crystal analyses of 3 and 4, the electron rich organic derivatives interact simultaneously with the two mercury centers via formation of long coordination bonds (Hg-N ) 2.82(1) and 2.93(1) Å in 3; Hg-O )2.71(2) and Hg(2)-O ) 2.77(2) Å in 4). As observed in the structure of 2, compound 3 and 4 form layered solids in which the monomers interact by Hg‚‚‚Cl and Hg‚‚‚F contacts. Finally, compound 1 readily catalyzes the polymerization of propylene sulfide.

In the crystalline state, the trinuclear mercury(II) complex [(o-C(6)F(4)Hg)(3)*mu(3)-acetone] forms cofacial dimers which are held by two mercurophilic interactions of 3.51 A. In this form, the complex displays an intense photoluminescence with a sharp emission centered at 480 nm.