Selective C H bond activation of ethane by free gold clusters

Abstract

The activation and potential dissociation of ethane mediated by small cationic gold clusters Au x + (x = 2-4) has been explored by infrared multiphoton dissociation (IR-MPD) spectroscopy and density functional theory (DFT) calculations. The calculations show that the interaction between the gold clusters and ethane is mainly governed by the mixing of the ethane CH 3 bond-forming orbitals-(CH 3) with gold d-orbitals. While the CC single bond appears to be unaffected, this mixing leads to the selective activation of up to two ethane C-H bonds and a reduction of the activation barrier for C-H bond dissociation to up to 0.82 eV, making the reaction kinetically feasible at room temperature. In agreement with this, experimental IR-MPD spectra of the complexes Au 2 (C 2 H 6) 2 + and Au 2 (C 2 D 6) 2 + reveal that the dominant product is one where a single ethane C-H bond is dissociated resulting in a complex which contains an ethyl group and a bridge-bonded H atom along with a second, adsorbed C 2 H 6 molecule. A similar C-H bond dissociation mechanism is theoretically predicted for the Au 3 (C 2 H 6) y + (y = 2,3) and Au 4 (C 2 H 6) y + (y = 2,3) complexes, albeit thermodynamically less favorable. IR-MPD spectra of Au 3 (C 2 H 6) y + (y = 2,3) and Au 4 (C 2 H 6) y + (y = 2,3) confirm the encounter product to be the dominant one, although the coexistence of isomers containing ethyl groups cannot be excluded. Various pathways for C-H bond activation are theoretically explored and the ethane activation mechanism is compared to the gold mediated activation of methane and ethylene. 65 spectra (I 0) in between successive FELICE pulses. The IR-MPD spectra shown in this contribution display the ratio 65

USc2C2 and USc2NC Clusters with U–C Triple Bond Character Stabilized Inside Fullerene Cages

“…The C81–C82 distance, however, is 1.62(2) Å, much longer than the above-mentioned C–C triple bonds or even a typical C–C single bond (ca. 1.54 Å) . Therefore, there is likely no bonding interaction between the two C atoms in the USc 2 C 2 moiety, a rare observation for an endohedral carbide cluster.…”

“…1.54 Å). 25 Therefore, there is likely no bonding interaction between the two C atoms in the USc 2 C 2 moiety, a rare observation for an endohedral carbide cluster.…”

Cluster Size Dependent Interaction of Free Manganese Oxide Clusters with Acetic Acid and Methyl Acetate

“…Previous spectroscopic studies on metal and metal oxide complexes demonstrated that the preparation of cluster complexes under the high-pressure multicollision conditions prevailing in the flow tube reactor is especially suitable for studying the initial steps of a chemical reaction, i.e., the fundamental interaction of the molecules with the clusters and the initial bond activation and bond breaking processes (see e.g. refs − ).…”

Theoretical investigation of C1–C4 hydrocarbons adsorption and separation in a porous metallocavitand

“…The higher binding energy of the C 2 H 6 is due to the mixing of the occupied π − (CH 3 ) orbitals with the Au( i ) orbitals resulting in an electron charge donation from C 2 H 6 to Au( i ) and a partial de-occupation of the π − (CH 3 ). 31 The partial de-occupation is reflected in the lowest unoccupied molecular orbital (LUMO) that is formed by the interaction of the occupied π − (CH 3 ) of ethane and unoccupied s-orbitals of Au( i ). The C 2 H 4 stabilizes the π mode adsorption and strengthens the Au–C bond by readily balancing between donation and back-donation of electrons which strongly influence the molecular adsorption.…”