Deprotonation reactions of 2-thiouracil with [2-(pyridin-2-yl)-phenyl]mercury(II) acetate. Structural and spectroscppic effects

Article abstract of DOI:10.1039/DT9960001973

The reaction of [2-(pyridin-2-yl)phenyl]mercury(II) acetate with 2-thiouracil (H₂tuc) in 1:1 and 2:1 mole ratio in methanol solution afforded [Hg(C₆H₄C₅H₄N)(H₂tuc)] and [({Hg(C₆H₄C₅H₄N)}₂(tuc)] respectively. The bimetallic complex crystallizes in the monoclinic space group P2₁/n with a = 10.706(1), b = 22.043(3), c = 11.126(1) A, β = 117.01(1)° and Z = 4. The complex molecules are associated in centrosymmetric dimers by weak intermolecular pyridine N ... Hg bond interactions. Of the two organometallic cations, one is bound to the thiouracil N(3) atom [Hg(1)-N(3) 2.12(1) A] and the other is S-co-ordinated [Hg(2)-S 2.350(5) A]. Atom Hg(1) also forms two weak intramolecular bonds with the O and S atoms and another secondary bond with the pyridine nitrogen of the Hg(1)(C₆H₄C₅H₄N) moiety [Hg(1) ... N 2.61(2) A]. This last type of intramolecular bond is also present, though a little longer [Hg(2) ... N 2.69(2) A], in Hg(2)(C₆H₄C₅H₄N), where Hg(2) is located 2.99(1) A from the non-co-ordinated nitrogen atom of the tuc^2- anion [N(1)]. On the grounds of a vibrational study of the two complexes, a scheme for IR-based diagnosis of the co-ordination of the 2-thiouracilate anions is proposed. The ¹H and ¹⁹⁹Hg NMR spectra of the bimetallic complex in CDCl₃ solution indicate that the N- and S-bound Hg(C₆H₄C₅H₄N) units interchange slowly, while the pyridine intramolecular N ... Hg interactions remain in both CDCl₃ and (CD₃)₂SO solutions.

Full text of DOI:10.1039/DT9960001973

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