A Unique Helicate Comprised of Four Cytosine Nucleobases and Four Metal Entities (PtII, PtII, AuIII, AuI). Implications for the Interactions of Linearly Coordinated Metal Ions with ­Nucleotide Duplexes12. Issue 8 (29th May 2013)

• Record Type: Journal Article
• Authors: Fusch, Gerhard; Zangrando, Ennio; Randaccio, Lucio; Lippert, Bernhard
• Is Part Of: Zeitschrift für anorganische und allgemeine Chemie. Volume 639:Issue 8/9(2013)
• Page Start: 1674
• Page End: 1679
• Publication Date: 2013-05-29
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry -- Periodicals; 540
• DOI: 10.1002/zaac.201300038
• Languages: English
• ISSNs: 0044-2313

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p> <bold>Abstract<italic>.</italic></bold> Reaction of <italic>trans</italic>‐[Pt(CH<sub>3</sub>NH<sub>2</sub>)<sub>2</sub>(1‐MeC‐<italic>N3</italic>)<sub>2</sub>]<italic>X</italic><sub>2</sub> (1‐MeC = 1‐methylcytosine; <italic>X</italic> = NO<sub>3</sub><sup>–</sup> or ClO<sub>4</sub><sup>–</sup>) with Na[AuCl<sub>4</sub>] in strongly alkaline aqueous solution yields an asymmetrical double helicate containing two central Pt<sup>II</sup> as well as Au<sup>III</sup> and Au<sup>I</sup> atoms, four 1‐methylcytosinato bridges (1‐MeC<sup>–</sup>‐<italic>N3, N4</italic>), two terminal methylamine and two bridging methylamido ligands, [Au<sub>2</sub>Pt<sub>2</sub>(CH<sub>3</sub>NH<sub>2</sub>)<sub>2</sub>(CH<sub>3</sub>NH)<sub>2</sub>(1‐MeC<sup>–</sup>)<sub>4</sub>]Cl<sub>2</sub><bold>·</bold>2H<sub>2</sub>O (<bold>2</bold>). The four 1‐MeC<sup>–</sup> ligands, which are pairwise oriented in head‐head fashion, are deprotonated at their N4 positions and cross‐linked by the gold ions. While one of the gold ions, Au<sup>I</sup>, adopts a linear coordination arrangement, the second, Au<sup>III</sup>, is square‐planar and completes its coordination arrangement through two methylamido ligands, which behave as bridging species between Au<sup>III</sup> and Pt. As a consequence of deprotonation of the original methylamine ligands, the nitrogen atoms of the CH<sub>3</sub>NH<sup>–</sup> bridges have become chiral. The four heavy metals form a diamond‐shaped plane, with an intramolecular Au<sup>III</sup><bold>···</bold>Au<sup>I</sup> distance of 3.053(4) Å. On the basis of the structure of cation <bold>2</bold> a new model is proposed how linear transition metal ions (M) might interact with (natural or artificial) nucleobases (L) within a double helix to produce compact <italic>M</italic><sub>4</sub>L<sub>4</sub> adducts.</p> </abstract>