Binding energies of palladium carbonyl cluster anions: Collision-induced dissociation of Pd3(CO)n− (n=0–6)

Spasov, Vassil A.; Ervin, Kent M.

doi:10.1063/1.477152

Cited by 44 publications

(27 citation statements)

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“…4 Gas-phase metal carbonyl ions have been studied extensively in mass spectrometry, [5][6][7] and the structures and bonding of these ions have been investigated with theory. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] The reactions of carbonyl ions have been well characterized, and bond energies have been determined, [21][22][23][24][25][26][27][28][29][30][31] but there is much less data on their spectroscopy. However, recent experiments have employed photoelectron spectroscopy to study a variety of metal carbonyl anions, providing vibrational information for the corresponding neutral ground states.…”

Section: Introductionmentioning

confidence: 99%

IR Photodissociation Spectroscopy and Theory of Au⁺(CO)_n Complexes: Nonclassical Carbonyls in the Gas Phase

et al. 2008

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Au+(CO)n complexes are produced in the gas phase via pulsed laser vaporization, expanded in a supersonic jet, and detected with a reflectron time-of-flight mass spectrometer. Complexes up to n = 12 are observed, with mass channels corresponding to the n = 2 and n = 4 showing enhanced intensity. To investigate coordination and structure, individual complexes are mass-selected and probed with infrared photodissociation spectroscopy. Spectra in the carbonyl stretching region are measured for the n = 3−7 species, but no photodissociation is observed for n = 1, 2 due to the strong metal cation-ligand binding. The carbonyl stretch in these systems is blue-shifted 50−100 cm-1 with respect to the free CO vibration (2143 cm-1), providing evidence that these species are so-called "nonclassical" metal carbonyls. Theory at the MP2 and CCSD(T) levels provides structures for these complexes and predicted spectra to compare to the experiment. Excellent agreement is obtained between experiment and theory, establishing that the n = 3 complex is trigonal planar and the n = 4 complex is tetrahedral. Disciplines Chemistry CommentsReprinted (adapted) ReceiVed: NoVember 21, 2007; In Final Form: December 18, 2007 Au + (CO) n complexes are produced in the gas phase via pulsed laser vaporization, expanded in a supersonic jet, and detected with a reflectron time-of-flight mass spectrometer. Complexes up to n ) 12 are observed, with mass channels corresponding to the n ) 2 and n ) 4 showing enhanced intensity. To investigate coordination and structure, individual complexes are mass-selected and probed with infrared photodissociation spectroscopy. Spectra in the carbonyl stretching region are measured for the n ) 3-7 species, but no photodissociation is observed for n ) 1, 2 due to the strong metal cation-ligand binding. The carbonyl stretch in these systems is blue-shifted 50-100 cm -1 with respect to the free CO vibration (2143 cm -1 ), providing evidence that these species are so-called "nonclassical" metal carbonyls. Theory at the MP2 and CCSD(T) levels provides structures for these complexes and predicted spectra to compare to the experiment. Excellent agreement is obtained between experiment and theory, establishing that the n ) 3 complex is trigonal planar and the n ) 4 complex is tetrahedral.

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Section: Introductionmentioning

confidence: 99%

IR Photodissociation Spectroscopy and Theory of Au⁺(CO)_n Complexes: Nonclassical Carbonyls in the Gas Phase

et al. 2008

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“…This is especially the case for surface sites of low metal coordination. Quantitative information on CO binding energies is available for clusters of the coinage metals Cu [37], Au [38,39], and Au-Ag mixtures [40], as well as for Pt [41,42] and Pd [43] clusters. In general, binding energies for rather small clusters are already close to binding energies on extended metal 5/27 surfaces.…”

Section: Cluster Reactivities and M N -Co Binding Energiesmentioning

confidence: 99%

The adsorption of CO on transition metal clusters: A case study of cluster surface chemistry

et al. 2009

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We present a discussion of recent experimental studies on the interaction of single CO molecules with transition metal clusters in the gas phase, typically in the size-range of 3 to more than 20 atoms, emphasizing specifically the insights gained from vibrational spectroscopy. Trends across the transition metals for molecular vs. dissociative chemisorption as well as for adsorption geometries are discussed and compared with the behaviour of CO adsorbed on extended surfaces. The dependence of the frequency of the internal CO stretch vibration on the size and charge of the cluster enables one to gauge quantitatively the effects of charge transfer between deposited nano-particles and the substrate as well as of electron transfer due to the binding of co-adsorbed species.

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“…In these clusters decarbonylation thresholds are smaller than both the electron affinity (thermionic emission threshold) and the metal-metal dissociation energy [6,7]. Besides fluorescence, evaporation of a ligand molecule should thus be the only process by which energy can be released from carbonyl clusters.…”

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Photon-Induced Thermal Desorption of CO from Small Metal-Carbonyl Clusters

et al. 2002

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Thermal CO desorption from photoexcited free metal-carbonyl clusters has been resolved in real time using two-color pump-probe photoelectron spectroscopy. Sequential energy dissipation steps between the initial photoexcitation and the final desorption event, e.g., electron relaxation and thermalization, have been resolved for Au 2 ͑CO͒ 2 and Pt 2 ͑CO͒ 5 2 . The desorption rates for the two clusters differ considerably due to the different numbers of vibrational degrees of freedom. The unimolecular CO-desorption thresholds of Au 2 ͑CO͒ 2 and Pt 2 ͑CO͒ 5 2 have been approximated by means of a statistical Rice-Ramsperger-Kassel calculation using the experimentally derived desorption rate constants. DOI: 10.1103/PhysRevLett.88.076102 PACS numbers: 68.43.Vx, 33.80.Eh, 36.40. -c, 42.65.Re Thermal desorption of a molecule from an equilibrated surface takes place due to statistical energy fluctuations among all degrees of freedom. There is a certain probability that energy is accumulated in a specific chemisorptive bond that exceeds the desorption threshold of an adsorbed molecule. As thermal desorption is a statistical process, which is usually described in terms of stochastic time evolution of the energy content of the dissociative mode [1], the desorption rate depends first of all on the desorption threshold and the total number of degrees of freedom. In isolated particles, the energy cannot simply be released to the surrounding by diffusion or heat transport as in solids. Therefore in small metal-adsorbate clusters a finite probability exists to release the energy by thermal electron emission (thermionic emission) or thermal desorption of a ligand molecule after reaching thermal equilibrium. The energy redistributes either into a particular degree of freedom, i.e., a particular electronic state having one electron less, or a dissociative final state.For photon-induced desorption processes, many dissipation steps are involved between the initial energy absorption and final ligand evaporation. Energy dissipation in photoexcited systems proceeds via electron relaxation and vibrational relaxation where the former process is usually faster than electron-vibrational coupling. Inelastic electron-electron scattering with time constants much less than 100 fs have been observed in optically excited bulk metals [2]. Similar relaxation times have also been observed for Pd and Au nanoparticles [3]. Even the smallest transition metal clusters of Pt, Pd, and Ni show electron relaxation times of about 100 fs [4,5]. Thermalization between the electronic and vibrational system is usually slower ranging to the ps regime.Transition metal-carbonyl clusters such as Pt n ͑CO͒ m 2 are excellent candidates to study photon-induced thermal desorption processes. In these clusters decarbonylation thresholds are smaller than both the electron affinity (thermionic emission threshold) and the metal-metal dissociation energy [6,7]. Besides fluorescence, evaporation of a ligand molecule should thus be the only process by which energy can be rele...

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Binding energies of palladium carbonyl cluster anions: Collision-induced dissociation of Pd3(CO)n− (n=0–6)

Cited by 44 publications

References 51 publications

IR Photodissociation Spectroscopy and Theory of Au⁺(CO)_n Complexes: Nonclassical Carbonyls in the Gas Phase

IR Photodissociation Spectroscopy and Theory of Au⁺(CO)_n Complexes: Nonclassical Carbonyls in the Gas Phase

The adsorption of CO on transition metal clusters: A case study of cluster surface chemistry

Photon-Induced Thermal Desorption of CO from Small Metal-Carbonyl Clusters

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Binding energies of palladium carbonyl cluster anions: Collision-induced dissociation of Pd3(CO)n− (n=0–6)

Cited by 44 publications

References 51 publications

IR Photodissociation Spectroscopy and Theory of Au+(CO)n Complexes: Nonclassical Carbonyls in the Gas Phase

IR Photodissociation Spectroscopy and Theory of Au+(CO)n Complexes: Nonclassical Carbonyls in the Gas Phase

The adsorption of CO on transition metal clusters: A case study of cluster surface chemistry

Photon-Induced Thermal Desorption of CO from Small Metal-Carbonyl Clusters

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Product

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IR Photodissociation Spectroscopy and Theory of Au⁺(CO)_n Complexes: Nonclassical Carbonyls in the Gas Phase

IR Photodissociation Spectroscopy and Theory of Au⁺(CO)_n Complexes: Nonclassical Carbonyls in the Gas Phase