Cu(i) and Ag(i) complexes of 7,10-bis-N-heterocycle-diazafluoranthenes: programmed molecular grids?

Abstract

Reactions of 7,10-disubstituted diazafluoranthene derivatives with three different silver(I) salts AgX (X = [PF₆]⁻, [SbF₆]⁻, [CB₁₁HCl₁₁]⁻) and [Cu(CH₃CN)₄]PF₆ afforded complexes exhibiting five different motifs. The crystal structures of the free ligands and nine new complexes from this series of reactions are reported. The use of 2,5-di-tert-butyl-7,10-di(pyridin-2-yl)-8,9-diazafluoranthene as a ligand leads to the formation of the tetranuclear compounds [Ag₄(C₃₂H₃₀N₄)₄][PF₆]₄·3C₆H₆·4MeCN, [Ag₄(C₃₂H₃₀N₄)₄][SbF₆]₄·4C₅H₁₂ and [Cu₄(C₃₂H₃₀N₄)₄][PF₆]₄·8C₃H₆O, which exhibit “propeller” and saddle-type geometry, respectively, as well as a dinuclear complex [Ag₂(C₃₂H₃₀N₄)₂][CHB₁₁Cl₁₁]₂·4C₆H₄Cl₂·CH₂Cl₂. The reactions involving the less sterically hindered 2,5-di-tert-butyl-7,10-di-(pyrimidin-2-yl)-8,9-diazafluoranthene and 2,5-di-tert-butyl-7,10-di(thiazol-2-yl)-8,9-diazafluoranthene afforded crystals of the dinuclear complexes [Ag₂(C₃₀H₂₈N₆)₂][PF₆]₂·0.5CH₂Cl₂·0.5C₆H₅Cl·0.5C₆H₁₂, [Ag₂(C₃₀H₂₈N₆)₂][SbF₆]₂·C₃H₆O·0.5C₆H₁₄·0.5C₆H₆, the polymeric species [Ag₂(C₂₈H₂₆N₄S₂)₂]_n·2n[PF₆]_n·nC₃H₆O and the tetranuclear compounds [Cu₄(C₂₆H₂₅N₄S₂)₄][PF₆]₄·2CHCl₃·2C₃H₆O and [Cu₄(C₃₀H₂₈N₆)₄][PF₆]₄·2.17H₂O, which possess saddle and grid-like architectures, respectively. Conformational analysis of the free ligands showed that they exhibit N–C–C–N torsion angles ranging from syn clinal (58°) to fully anti-periplanar conformations; the syn clinal conformation dominates in the complexes. The relative energies of the possible structural conformations of the synthesized ligands, as well as of oxazole disubstituted diazafluoranthenes, were calculated using density functional theory at the B97D/Def2-TZVPP level of theory.