Preparation and characterization of ultrathin [Ru(CO)3Cl2]2 and [BMIM][Tf2N] films on Al2O3/NiAl(110) under UHV conditions

Abstract

Towards a better understanding of the interface chemistry of ionic liquid (IL) thin film catalytic systems we have applied a rigorous surface science model approach. For the first time, a model homogeneous catalyst has been prepared under ultrahigh vacuum conditions. The catalyst, di-μ-chlorobis(chlorotricarbonylruthenium) [Ru(CO)(3)Cl(2)](2), and the solvent, the IL 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [BMIM][Tf(2)N], have been deposited by physical vapor deposition onto an alumina model support [Al(2)O(3)/NiAl(110)]. First, the interaction between thin films of [Ru(CO)(3)Cl(2)](2) and the support is investigated. Then, the ruthenium complex is co-deposited with the IL and the influence of the solvent on the catalyst is discussed. D(2)O, which is a model reactant, is further added. Growth, surface interactions, and mutual interactions in the thin films are studied with IRAS in combination with density functional (DFT) calculations. At 105 K, molecular adsorption of [Ru(CO)(3)Cl(2)](2) is observed on Al(2)O(3)/NiAl(110). The IRAS spectra of the binary [Ru(CO)(3)Cl(2)](2) + [BMIM][Tf(2)N] and ternary [Ru(CO)(3)Cl(2)](2) + [BMIM][Tf(2)N] + D(2)O show every characteristic band of the individual components. Above 223 K, partial decomposition of the ruthenium complex leads to species of molecular nature attributed to Ru(CO) and Ru(CO)(2) surface species. Formation of metallic ruthenium clusters occurs above 300 K and the model catalyst decomposes further at higher temperatures. Neither the presence of the IL nor of D(2)O prevents this partial decomposition of [Ru(CO)(3)Cl(2)](2) on alumina.

Ionic-Liquid-Modified Hybrid Materials Prepared by Physical Vapor Codeposition: Cobalt and Cobalt Oxide Nanoparticles in [C1C2Im][OTf] Monitored by In Situ IR Spectroscopy

“…In IL surface science we start from ultraclean, atomically well-defined single crystals to prepare IL/solid interfaces at different levels of complexity . In our previous work we have explored IL films on metal surfaces, − on thin oxide films, − and on oxide-supported metal particles. , Typically, these IL films are prepared by physical vapor deposition (PVD). Model interfaces prepared in this way can then be investigated by a large spectrum of surface science methods, e.g., photoelectron spectroscopies, ,, vibrational spectroscopies, − ,,, or scanning probe microscopies. − These studies have provided insight into the adsorption, structure formation, and reaction of ILs on surface at an unprecedented level of detail.…”

Alkyl chain length-dependent surface reaction of dodecahydro-N-alkylcarbazoles on Pt model catalysts

“…This well-ordered oxide film is widely used as a support for model catalyst preparation. [19][20][21][22][23] Due to its low thickness, charging effects during electron spectroscopy measurements are avoided. Pt is deposited on top of the Al 2 O 3 support via physical vapor deposition (PVD).…”

Dynamic equilibria in supported ionic liquid phase (SILP) catalysis: in situ IR spectroscopy identifies [Ru(CO)xCly]n species in water gas shift catalysis

“…carbonyl features from the Ru-species (2200 -1700 cm -1 other Cl-free ILs. 20,[23][24] We attribute the occurrence of the new peaks to a transformation in the IL phase. The most likely scenario is a splitting of the dimer by addition of Cland formation of [Ru(CO) 3 Cl 3 ] -, a reaction which was proven previously by experimental and theoretical studies.…”

“…The BP86 [15][16] functional was used in combination with the def2-TZVPP 17 basis set, which was augmented by diffuse functions for C, Cl, H and O atoms taken from the aug-cc-PVTZ [18][19] basis set. This approach has been successfully applied to similar systems 20 . Optimizations were done without any constraints and vibrational frequencies were determined using the analytical derivatives of the energy as implemented in the AOFORCE module within TURBOMOLE.…”

“…The more pronounced red-shift with respect to previously published IRAS data is attributed to the solvent effects due to the increased amount of IL. 20 With increasing IL concentration in the 5:1 mixture (red curve), a small feature appears at 1950 cm -1 and the intensity of the peak at 2122 cm - corresponding TIR spectra are included in Fig. 1b (in green).…”