Pt(2,2'-bpy)(O2CCF3)2 as a terminator for [Ag(O2CCF3)]n aggregates — Syntheses and structures of heterobimetallic PtIIAgI complexes

Abstract

The reactions between Pt(2,2′-bpy)(O2CCF3)2 and Ag(O2CCF3) have been found to consistently produce heterobimetallic complexes where the [Pt(2,2′-bpy)]2+ unit acts as a terminator for various [Ag(O2CCF3)]n aggregates. The stoichiometry and the structure of the heterobimetallic complex obtained is dependent on the ratio of Pt(2,2′-bpy)(O2CCF3)2 and Ag(O2CCF3) used in the synthesis. When a 1:1 ratio of Pt/Ag was used, a heteronuclear complex Pt2Ag2(2,2′-bpy)2(O2CCF3)6 (1a) was obtained where the four metal ions have a linear Pt-Ag-Ag-Pt arrangement. Molecules of 1a stack in the crystal lattice via intermolecular Pt···Pt interactions to form a linear 1D extended structure. A structural isomer of 1a, Pt2Ag2(2,2′-bpy)2(O2CCF3)6 (1b), where the four metal ions have an “L”-shaped arrangement was also identified and characterized, which forms a zig-zag 1D extended structure via intermolecular Pt···Pt interactions. When the 1:2 and the 1:3 ratios of Pt/Ag were used, heteronuclear complexes Pt2Ag4(2,2′-bpy)2(O2CCF3)8 (2) and Pt2Ag6(2,2′-bpy)2(O2CCF3)10 (3) were isolated, respectively, where the Ag(I) ions form cyclic structures with the Pt(2,2′-bpy)(O2CCF3)2 units at the terminal positions. Further increase of the amount of Ag(O2CCF3) used in the synthesis did not lead to the isolation of larger aggregates. The structures of compounds 1a, 1b, 2, and 3 were determined by single-crystal X-ray diffraction analyses. 19F NMR spectroscopic analysis established that these heterobimetallic complexes undergo dynamic exchanges in solution.Key words: heterobimetallic complexes, structure, silver, platinum, metal-metal interaction.