Pt as mediator of strong antiferromagnetic coupling between two CuII ions in a heteronuclear CuIIPtIICuII complex of the model nucleobase 1-methylcytosinate

Alexander Hegmans, Ennio Zangrando, Eva Freisinger, Fabio Pichierri, Lucio Randaccio, Carlo Mealli, Michael Gerdan, Alfred X. Trautwein, Bernhard Lippert

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)

Abstract

The tetrakis(1-methylcytosine) complex [Pt(1-MeC-N3)4](NO3)2 (1) in its head-tail-head-tail (htht) rotamer form binds upon deprotonation of the exocyclic amino group of 1-MeC, two CuII at either side of the central PtII to give trinuclear cations [Pt(1-MeC-)4-Cu2X2]n+ (2) with X = Cl-, H2O, NSC-, N3-. X-ray crystal structure analyses of [Pt(1-MeC-)4Cu2(Cl)1.6(H2O) 0.4(NO3V0.4-1.6H2O (2a) and [Pt(1-MeC-)4Cu2-(H2O) 2](NO3)2 · 3H2O (2b) reveal short Cu-Pt distances of 2.519(2)-2.531(2)Å. These compounds are diamagnetic as a result of the strong exchange interaction (J = 980 ± 30 cm-1 (2a)), despite a separation of approximately 5 Å between the CuII centers. MO considerations are in agreement with the assumption that PtII acts as a mediator between the two CuII centers. A second trinuclear complex derived from the hhhh rotamer of 1 containing both CoIII and Na+ [Pt(1-Me-C-)4Co(H2O)Na] (NO3)2·2 H2O (3) has been isolated in very low yield and characterized by X-ray structure analysis. The CoIII center is bound to four amide N atoms and forms a bond to Pt (2.402(2) Å), whereas the Na+ ion is bound to the four oxygen atoms of the nucleobase. A general route for the preparation of heteronuclear MPtM and MPtM' compounds is described.

Original languageEnglish
Pages (from-to)3010-3018
Number of pages9
JournalChemistry - A European Journal
Volume5
Issue number10
DOIs
Publication statusPublished - 1999 Oct
Externally publishedYes

Keywords

  • Copper
  • Magnetic properties
  • Metal-metal interactions
  • Nucleobases
  • Platinum

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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