Supramolecular Structures from Polycarbene Ligands and Transition Metal Ions

Rit A, Pape T, Hepp A, Hahn FE

Research article (journal)

Abstract

The synthesis of cylinder-type carbene complexes from polycarbene ligands and coinage metal ions via metal-controlled self-assembly has been explored. Imidazole reacts with 1,2,4,5-tetrabromobenzene or 1,3,5-tribromobenzene to give 1,2,4,5-tetrakis(1-imidazolyl)benzene (1) and 1,3,5-tris(1-imidazolyl)benzene (3), respectively. The tetrakisimidazolium salts of type H4-2a,b(Br)4 and the trisimidazolium salts of type H3-4a,b(Br)3 have been prepared by alkylation of the remaining free imines of the tetrakis- and trisimidazoles (H4-2a4+, H3-4a3+: R = n-butyl; H4-2b4+, H3-4b3+: R = ethyl). Polyimidazolium salts H4-2a,b(PF6)4 and H3-4a,b(PF6)3 have been synthesized by anion exchange from H4-2a,b(Br)4 and H3-4a,b(Br)3. Two equivalents of tetraimidazolium salt H4-2a(Br)4 or H4-2a,b(PF6)4 reacts with four equivalents of Ag2O to yield via self-assembly molecular cylinders of type [Ag4(2a)2]Y4 (Y− = [AgBr2]− and/or Br−) or [Ag4(2a,b)2](PF6)4, respectively. Similarly, reaction of two equivalents of trisimidazolium salts H3-4a(Br)3 or H3-4a,b)(PF6)3 with three equivalents of Ag2O yields the molecular cylinder [Ag3(4a)2](Y)3 (Y− = [AgBr2]− and/or Br−) or [Ag3(4a,b)2](PF6)3, respectively. Transmetalation of [Ag4(2a,b)2](PF6)4 with four equivalents of [AuCl(SMe2)] leads to the formation of the tetranuclear gold(I) complex [Au4(2a,b)2](PF6)4 with retention of the metallosupramolecular assembly. Analogously, transmetalation of [Ag3(4a,b)2](PF6)3 with three equivalents of [AuCl(SMe2)] or CuBr yields the trinuclear gold(I) complexes [Au3(4a,b)2](PF6)3 or the copper(I) complexes [Cu3(4a,b)2](PF6)3, respectively. Contrary to the metallosupramolecular assemblies of type [M4(2a)2]4+ (M = Ag+, Au+), tetrakisimidazolium salt H4-2a(Br)4 reacts with K2PtCl4 in the presence of NaOAc to yield the square-planar dinuclear complex [Pt2(2a)Br4].

Details zur Publikation

Pages: 14
Release year: 2010
Language in which the publication is written: English
Link to the full text: http://pubs.acs.org/doi/abs/10.1021/om101102j