Interaction of the Bifunctional Lewis Acid 1,2-Bis(chloromercurio)tetrafluorobenzene with Aldehydes, Nitriles, and Epoxides

Abstract

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.

Poly‐Boron, ‐Silicon, and ‐Gallium Lewis Acids by Hydrometallation of 1,5‐ and 1,8‐Dialkynylanthracenes

“…As mentioned above, most of the poly‐Lewis acids exhibit a flexible organic framework and are potentially capable of complexing a wide range of guest species such as anions or (small) Lewis basic molecules. Just a few examples of polydentate Lewis acids with a rigid organic backbone have been synthesised, for example, by Gabbaï et al,1a,1c Jurkschat and co‐workers2b or Katz 12…”

Complexation of methylparathion and bis(2-hydroxyethyl)sulfide by the tridentate lewis acid [(o-C6F4Hg)3]

“…Fluorinated polyfunctional organomercurials such as pentameric perfluoroisopropylidenemercury [11], trimeric perfluoro-ortho-phenylene mercury ([(o-C 6 F 4 Hg) 3 ], 1), 5,6,12 and 1,2-bis(chloromercurio)tetrafluorobenzene [13][14][15][16][17][18] have attracted a great deal of attention because the electron withdrawing capacity of the fluorinated ligands leads to an increase in the Lewis acidity of the mercury centers. The trinuclear derivative 1 is one of the most studied examples of fluorinated polyfunctional organomercurials.…”

Vibrational and DFT analysis of perfluoro-o-phenylenemercury compounds

“…The 100 cm À1 region of experimental Raman is not significative because very close to the cut of Rayleigh filter of the FT-Raman instrument employed. Compound 2 belong to P21/n space groups, with Z ¼ 8 and a double occupancy of general position [19]. For this reason we expect doubling of spectral features, with the same intensities.…”

“…Experimental data of 2 [19] show that CeC and CeF bonds have very similar length, also if the measurement's error is high. DFT calculation discriminate between these lengths, and basis set effect is very modest.…”

“…[19] 2 DFTa 6-31g In Fig. 1 a and b solid state experimental and DFT-c infrared and Raman spectra are reported.…”