Synthesis and Characterization of a Series of Ruthenium Tris(β‐diketonato) Complexes by an UHV‐STM Investigation and Numerical Calculations

Abstract

Abstract A series of ruthenium tris(β‐diketonate) complexes was investigated by using electrochemistry, UV/Vis spectroscopy, 1 H NMR and 13 C NMR spectroscopy and FAB mass spectroscopy. Several new mononuclear mixed‐ligand ruthenium(III) complexes were prepared: with three dibenzoylmethanate ions (dbm) {[Ru(dbm) 3 ] ( 1 )}, one or two acetylacetonate ions (2,4‐pentanedionate, acac) {[Ru(dbm) 2 (acac)] ( 2 ), [Ru(dbm)(acac) 2 ] ( 3 )}, two acetonitrile ligands {[Ru(dbm) 2 (CH 3 CN) 2 ][CF 3 SO 3 ] ( 4 )} or a functionalized acetylacetonate ion {[Ru(dbm) 2 (acac‐I)] ( 5 ) (acac‐I = 3‐iodo‐2,4‐pentanedionate ion), [Ru(dbm) 2 (acac‐Br)] ( 6 ) (acac‐Br = 3‐bromo‐2,4‐pentanedionate ion)}. In addition, X‐ray structures for complexes 1 , 2 , 3 , 4 and 6 were determined. Scanning tunnelling microscopy measurements at liquid He temperature and in anultra‐high vacuum (UHV‐STM) were conducted on complex 1 on a Ag(111) surface. This indicates that the complex can be successfully evaporated and observed after adsorption onto a metallic substrate. Analysis of the STM images, supported by adsorption and STM image calculations, demonstrates that the molecules exist in two stable forms when adsorbed onto the surface.