Interaction of the bifunctional Lewis acid 1,2-bis(chloromercurio)tetrafluorobenzene with aldehydes, nitriles, and epoxides

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) A. 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 Angstrom). 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) Angstrom in 3; Hg-O =2.71(2) and Hg(2)-0 = 2.77(2) Angstrom 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.