Infrared Signature of Structural Isomers of Gas–Phase M+(N2O)n (M = Cu, Ag, Au) Ion–Molecule Complexes

Cunningham, Ethan M.; Gentleman, Alexander S.; Beardsmore, Peter W.; Iskra, Andreas; Mackenzie, Stuart R.

doi:10.1021/acs.jpca.7b07628

Cited by 15 publications

(47 citation statements)

References 44 publications

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“…The second spectral feature undergoes a smooth red-shift (or decreasing blue-shift relative to the first band) with increasing ligand number from 2316 cm À1 for n = 2 to 2274 cm À1 for n = 7. In these regards, the trends in the spectra of the Co + (N 2 O) n -Ar complexes show close similarity with those reported previously for the coinage metal N 2 O complexes 24 and a similar rationale can be applied to their understanding. Fig.…”

Section: + (N 2 O) N -Ar Irpd Spectrasupporting

confidence: 85%

“…In contrast, only subtle differences were observed in the structures and spectra of N 2 O complexes with Cu + , Ag + and Au + . 24 The differences here appear to correlate with the importance of low-lying excited electronic states and, in particular, the differing effects successive ligation has on the ground and excited states of the metal ions (see Fig. 8).…”

Section: Discussionmentioning

confidence: 90%

“…The instrument and technique employed in these studies have been described previously 24,39 and only brief details are given here. Gas-phase M + (N 2 O) n (M = Co, Rh, Ir) complexes and their argon-tagged counterparts are formed by entraining the products of focussed 532 nm pulsed laser ablation of a rotating metal disc in a 6 bar pulse of Argon carrier gas seeded with 0.6% N 2 O.…”

Section: Methodsmentioning

confidence: 99%

“…As the 7s orbital is antibonding with respect to the NQN bond, this results in a slightly stronger NQN bond reflected in a spectral blue-shift. 13,14,24 The two bands in the observed spectrum clearly indicate the presence of both O-and N-bound ligands. Given the relative energies of the different isomers, it is inconceivable that we generate a pure population of the 3 Co + N 1 O 1 structure and we conclude that a mixture of isomers is present in our molecular beam.…”

Section: + (N 2 O) N -Ar Irpd Spectramentioning

confidence: 96%

“…[15][16][17][18][19][20][21][22][23] We recently reported a spectroscopic study of M + (N 2 O) n (M = Cu, Ag, Au) complexes in which infrared photodissociation (IRPD) spectroscopy was combined with quantum chemical calculations to identify common structural binding motifs. 24 Spectroscopically distinct nitrogen-and oxygen-bound ligands were identified giving rise to a rich diversity of structural isomers. However, in practical NO x -reduction catalysis, it is not the coinage metals which are typically used but the platinum group metals.…”

Section: Introductionmentioning

confidence: 99%

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Structural isomers and low-lying electronic states of gas-phase M⁺(N₂O)_n (M = Co, Rh, Ir) ion–molecule complexes

Cunningham

Gentleman

Beardsmore

et al. 2019

Phys. Chem. Chem. Phys.

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Section: + (N 2 O) N -Ar Irpd Spectrasupporting

confidence: 85%

Section: Discussionmentioning

confidence: 90%

Section: Methodsmentioning

confidence: 99%

Section: + (N 2 O) N -Ar Irpd Spectramentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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Structural isomers and low-lying electronic states of gas-phase M⁺(N₂O)_n (M = Co, Rh, Ir) ion–molecule complexes

Cunningham

Gentleman

Beardsmore

et al. 2019

Phys. Chem. Chem. Phys.

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The impact of optical excitation on the binding in complexes of the cationic gold dimer: Au2+N2${\rm{Au}_{2}^{+}} {\rm{N}_{2}} $ and Au2+N2O${\rm{Au}_{2}^{+}} {\rm{N}_{2}{\rm{O}}} $

et al. 2022

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The vibrationally resolved Ã2Σ+ ← trueX∼2${\tilde{\rm{X}}}^{2} $Σ+ transitions of Au2+N2${\rm{Au}_{2}^{+}} {\rm{N}_{2}} $ and Au2+normalN2O${\rm{Au}_{2}^{+}} {\rm{N}_{2}{\rm{O}}} $ are reported together with a detailed characterization of important geometric and electronic properties, enabling a deep understanding of the bonding mechanism at the molecular level. Comparison with time‐dependent density functional theory calculations reveals that the ligand stabilizes the Au2+${\mathrm{Au}}_{2}^{+}$ entity in the trueX∼2${\tilde{\rm{X}}}^{2} $Σ+ state by donating electron density into the half‐filled bonding orbital leading to the strengthening of the Au-Au$\text{Au-Au}$, N-N$\text{N-N}$, and N-O$\text{N-O}$ bonds. This effect is reversed in the Ã2Σ+ state, where the Au-Au$\text{Au-Au}$ bonding orbital is already filled and the ligand destabilizes the Au-Au$\text{Au-Au}$ bond by donating into the antibonding orbitals of Au2+${\mathrm{Au}}_{2}^{+}$. The spectral detail obtained provides a deep understanding of the interplay of multiple electronic states in gas‐phase metal‐complex cations, opening the door for a systematic approach in the study of excited state reactivity in organometallic chemistry. Key points High‐resolution spectroscopic characterization of Au2+normalL${\mathrm{Au}}_{2}^{+}\text{L}$ complexes by photodissociation of mass‐selected ions in the optical range and determination of fundamental molecular constants and ligand binding energies Detailed insight into geometric and electronic structure of ground and excited state of catalytically relevant gold cluster cations Effect of ligands on chemical bonding and reactivity of Au2+${\mathrm{Au}}_{2}^{+}$ in ground and excited electronic state

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Infrared Spectroscopy of Au+(CH4) n Complexes and Vibrationally-Enhanced C–H Activation Reactions

et al. 2017

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solvation, counterion, or defect effects. In turn, these shed light on the mechanism by which ligand activation occurs, leading to enhanced understanding of catalytic reactivity. Many industrial heterogeneous catalysts typically comprise multiple components, with reactions assumed to occur at metal defects supported by a macroscopic bulk structure [1]. The model systems studied can capture some of the features and energetics of the surface of catalysts [2], without complications arising from the bulk structure. The simplified nature of these model complexes also makes them tractable to theoretical studies which, coupled with experimental data, can provide a deeper understanding of fundamental interactions involved. These studies are often too computationallyintensive to perform rigorously on real systems.The interaction and reaction of methane with transition metal ions is of particular practical interest. As the simplest saturated hydrocarbon, methane serves as a key model for understanding metal ion-hydrocarbon systems. The activation of methane is an intensively studied topic in catalysis [3][4][5]. Methane is the primary component in natural gas (typically 80-90%-[4]) and with depleting petroleum reserves, the possibility of easily converting methane to more valuable chemicals and fuels would lead to its use as an abundant hydrocarbon feedstock.For complete methane activation to occur, at least one of the four strong C-H bonds (bond dissociation energy of 439 kJ mol −1 -[6]) must undergo bond scission. This is made challenging by the paucity of low-energy empty and high-energy filled orbitals in methane, making it relatively inert to reaction under most conditions [3]. The classic industrial route used to convert methane into useful reagents involves the initial conversion of methane to syngas (CO + H 2 ) via steam reforming, followed by the conversion of this syngas into a range of hydrocarbons or alcohols [3][4][5]. Despite representing a useful H 2 source, the steam Abstract A combined spectroscopic and computational study of gas-phase Au + (CH 4 ) n (n = 3-8) complexes reveals a strongly-bound linear Au + (CH 4 ) 2 core structure to which up to four additional ligands bind in a secondary coordination shell. Infrared resonance-enhanced photodissociation spectroscopy in the region of the CH 4 a 1 and t 2 fundamental transitions reveals essentially free internal rotation of the core ligands about the H 4 C-Au + -CH 4 axis, with sharp spectral features assigned by comparison with spectral simulations based on density functional theory. In separate experiments, vibrationally-enhanced dehydrogenation is observed when the t 2 vibrational normal mode in methane is excited prior to complexation. Clear infrared-induced enhancement is observed in the mass spectrum for peaks corresponding 4u below the mass of the Au + (CH 4 ) n=2,3 complexes corresponding, presumably, to the loss of two H 2 molecules.

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Infrared Signature of Structural Isomers of Gas–Phase M⁺(N₂O)_n (M = Cu, Ag, Au) Ion–Molecule Complexes

Cited by 15 publications

References 44 publications

Structural isomers and low-lying electronic states of gas-phase M⁺(N₂O)_n (M = Co, Rh, Ir) ion–molecule complexes

Structural isomers and low-lying electronic states of gas-phase M⁺(N₂O)_n (M = Co, Rh, Ir) ion–molecule complexes

The impact of optical excitation on the binding in complexes of the cationic gold dimer: Au2+N2${\rm{Au}_{2}^{+}} {\rm{N}_{2}} $ and Au2+N2O${\rm{Au}_{2}^{+}} {\rm{N}_{2}{\rm{O}}} $

Infrared Spectroscopy of Au+(CH4) n Complexes and Vibrationally-Enhanced C–H Activation Reactions

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Infrared Signature of Structural Isomers of Gas–Phase M+(N2O)n (M = Cu, Ag, Au) Ion–Molecule Complexes

Cited by 15 publications

References 44 publications

Structural isomers and low-lying electronic states of gas-phase M+(N2O)n (M = Co, Rh, Ir) ion–molecule complexes

Structural isomers and low-lying electronic states of gas-phase M+(N2O)n (M = Co, Rh, Ir) ion–molecule complexes

The impact of optical excitation on the binding in complexes of the cationic gold dimer: Au2+N2${\rm{Au}_{2}^{+}} {\rm{N}_{2}} $ and Au2+N2O${\rm{Au}_{2}^{+}} {\rm{N}_{2}{\rm{O}}} $

Infrared Spectroscopy of Au+(CH4) n Complexes and Vibrationally-Enhanced C–H Activation Reactions

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Infrared Signature of Structural Isomers of Gas–Phase M⁺(N₂O)_n (M = Cu, Ag, Au) Ion–Molecule Complexes

Structural isomers and low-lying electronic states of gas-phase M⁺(N₂O)_n (M = Co, Rh, Ir) ion–molecule complexes

Structural isomers and low-lying electronic states of gas-phase M⁺(N₂O)_n (M = Co, Rh, Ir) ion–molecule complexes