Isolation of cationic digold-frame with free carboxylic acid pendants

Abstract

Use of different diphosphines enables the isolation and crystallographic characterization of gold pyridylcarboxylate complexes with different structural motifs. Dppm [bis(diphenylphosphino)methane] supports side-by-side-like complexes [Au2(dppm)(IsonicH)2]2+ (isonicH = 4-NC5H4CO2H) with aurophilic and π⋯π interactions of the pyridyl rings. Use of dppen [1,2-bis(diphenylphosphino)ethylene] removes the latter interaction but keeps the orthogonal closed-shell interaction of Au(I) in [Au2(dppen) (IsonicH)2]2+. The ligand dppe [1,2-bis(diphenylphosphino) ethane] helps to push the gold centers apart in [Au2(dppe)(isonicH) 2]2+ and remove both interactions. These digold complexes are potential metalloligands that carry functional acids which can be conveniently activated by deprotonation. © The Royal Society of Chemistry 2009.