UHV-STM Investigations and Numerical Calculations of a Ruthenium β-Diketonato Complex with Protected Ethynyl Ligand: [Ru(dbm)₂(acac-TIPSA)]

Abstract

ABSTRACT:The quest of molecular electronic devices necessitates addressing model molecular systems as starting points. Among the targeted functions, electron transfer between specific moieties inside a molecule is expected to play a fundamental role for ultimate logical gates. Here we propose a coordination complex exhibiting two inorganic centers (Ru and Si) that constitutes a step towards a more complex architecture. Starting from the complex 1 [Ru(dbm) 2 (acac-I)] (dbm = dibenzoylmethanate ion, acac-I = 3-iodo-2,4-pentanedionate ion), the complex 2 [Ru(dbm) 2 (acac-TIPSA)] (acac-TIPSA=3-(triisopropylsilyl)acetylene-2,4-pentanedionate ion) was obtained through Sonogashira cross coupling reaction under classical conditions. This complex 2 was characterized by elemental analysis, IR, 1 H NMR, 13 C NMR, UV-Vis, cyclic voltammetry, mass spectroscopy as well as X-ray single crystal diffraction. It crystallized with empirical formula of C 46 H 49 O 6 Ru 1 Si 1 in a monoclinic crystal system and space group P2 1 /c with a = 21.077(3) Å, b = 9.5130(7) Å, c = 21.8790(12) Å, = 94.125(7)°, V = 4375.5(7) Å 3 and Z = 4. Additionally, scanning tunneling microscopy measurements at liquid He temperature and in an ultra-high vacuum (UHV-STM) were conducted on complex 2 on a Ag(111) surface. The STM images, supported by adsorption and STM image calculations, demonstrate that the molecules exist in two stable forms when adsorbed on the metallic surface.

UHV deposition and characterization of a mononuclear iron(III) β-diketonate complex on Au(111)

“…On the contrary, Cu(hfac) 2 adsorbs on SiO 2 without fragmentation, thus making reduction to Cu metal less favoured [ 27 ]. In the case of Cr(dbm) 3 , dbm − = dibenzoylmethanide, the STM investigation revealed bi-lobed features associated with free dbm – , suggesting that the molecule dissociatively interacts with the Cu(100) surface, while the less reactive dbm-based Ru complexes seem to adsorb as intact molecules on Ag(111) [ 28 – 29 ].…”

Observation and manipulation of tris(dibenzoylmethanato)ruthenium molecules by low temperature scanning tunnelling microscopy

“…In previous papers, we reported the first STM characterization of mononuclear ruthenium complexes with different ligands [18,19]. These molecules are of peculiar interest in the route towards the synthesis of larger entities devoted to charge transfer.…”

Spectral signature of a Ru(ii, iii, iv) complex: a combined experimental and theoretical investigation

“…More details about the experimental UV-Vis data can be found in our previous work. 15 The goal of the present contribution is to clearly describe the electronic structure of the different forms of the title compound and to assign all main bands which appear in the UV-Vis spectra with the aim of identifying the spectral signature of the degree of oxidation of the ruthenium atom within the complex.…”