(Ethylenediamine)Pt(uracilate)]4 – A Metal Analogue of Calix[4]arene: Coordination Chemistry of Its 1,3-Alternate Conformer towards First-Row Transition-Metal Ions

Abstract

The open “molecular box” [(en)Pt(U-N,N)]4 (1) (where en = structurally characterized heteronuclear compounds show a 1,3-alternate arrangement of the uracil nucleobases. Pt–M ethylenediamine, U = uracil dianion) is able to act as an efficient ligand for additional metal ions. Reactions of the 1,3contacts are in the range 2.743(2)–2.804(2) A; the Pt atoms act as weak σ donors to the heterometals. In spite of the high alternate conformer of 1 with divalent metal ions result in the formation of octanuclear compounds of the general formula degree of positive charge associated with compounds 2a–5, they do not behave as hosts for anions. This is a consequence [(en)Pt(U-N,N,O,O)M]4X8 [M = Cu2+, X = Cl (2a), X = (SO4)0.5 (2b), and M = Co2+ (3), Ni2+ (4), Zn2+ (5) with X = of the orientation of the four nucleobases which, in contrast to a cone arrangement, does not produce a sufficiently large (SO4)0.5], in which the heterometals are bound at the exocyclic oxygen atoms of the uracil nucleobases. The cavity for the incorporation of anions.