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) 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.