A quantitative measure of the ionicity of selected iron hydride species by examination of the deuterium quadrupole coupling constant (DQCC)

Field, Leslie D.; Shaw, Warren J.; Clentsmith, Guy K. B.

doi:10.1016/j.jorganchem.2007.03.024

Cited by 4 publications

(4 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Valuable informations about coordination modes of adsorbed species such as hydrides can be extracted from 2 H NMR spectra, since this technique is highly sensitive to the very local structure. It has been already intensively used in the context of transition-metal complexes, [28][29][30][31][32][33][34][35] clusters, [36][37][38][39] and more recently on Ru NPs. 27 Besides, thanks to a recent theoretical study, 40 the authors of the present work have pointed out the importance of a combined theoretical/ experimental approach to improve the interpretation of 2 H NMR spectra.…”

Section: ' Introductionmentioning

confidence: 99%

A Density Functional Theory Study of Spectroscopic and Thermodynamic Properties of Surfacic Hydrides on Ru (0001) Model Surface: The Influence of the Coordination Modes and the Coverage

et al. 2010

View full text Add to dashboard Cite

The characterization of hydrides on the surface of bulk metals and organometallic nanoparticles is of primary importance, especially in the context of catalysis, such as olefin hydrogenation. Although hydride titration as well as combination of nuclear magnetic resonance (NMR), and to a lesser extent infrared (IR) spectroscopies, confirm the presence and the potential reactivity of these simple species, the unambiguous characterization of their coordination on the surface and subsurface is still challenging owing to the number of degrees of freedom accessible at intermediate coverage rate. In this work, the influence of varying coordination modes (bridging, face capping, terminal, subsurfacic) and coverage upon the thermodynamic, kinetic, and spectroscopic properties have been investigated by means of density functional theory (DFT) calculations achieved on a ruthenium slab model. The predicted IR and 2H NMR observables reinforce the previous spectral assignment. Interestingly, following our seminal work for a monolayer coverage value (Φ) of 1/4 (Chem. Phys. Chem. 2009, 10, 2939), quadrupolar parameters obtained for higher Φ confirm that experimental 2H NMR spectra measured on Ru nanoparticles result from the presence of deuterides adsorbed on terminal, 2-fold and 3-fold symmetry sites. The kinetic and thermodynamic parametersnamely, diffusion barriers for the former and adsorption energies and phase diagrams for the lattershow that the probability of finding a subsurfacic hydride increases with Φ, whereas the saturation threshold on pristine Ru surfaces should stay close to the unityfor very low and moderate values of H2 pressurein order to ensure favorable thermodynamic conditions. Finally, this study partially opens the route to DFT studies of multistep hydrogenation reactions at the surface of ruthenium nanoparticles monitored by spectroscopic techniques. Conversely, it also demonstrates that the use of finite size models will be mandatory in the future if one wants to reach a reliable description of the metallic nanoparticle properties.

show abstract

Section: ' Introductionmentioning

confidence: 99%

A Density Functional Theory Study of Spectroscopic and Thermodynamic Properties of Surfacic Hydrides on Ru (0001) Model Surface: The Influence of the Coordination Modes and the Coverage

et al. 2010

View full text Add to dashboard Cite

show abstract

“…The reaction performed at 27 °C generated the thermodynamic product trans ‐(dmpe) 2 FeH(SCHNPh), or trans ‐(dmpe) 2 Fe(SCHNPh) 2 when more PhNCS was added (Figure ). The 1 : 1 reaction between alkyl isothiocyanate RNCS (R=Me, Et) and cis ‐(dmpe) 2 FeH 2 gave cis ‐(dmpe) 2 FeH(SCHNR) as the kinetic product, which gradually isomerized to the more stable trans isomer ,. Interestingly, adding the second equivalent of RNCS did not form the expected bis‐insertion product, but instead produced an iron hydride complex ligated by the dimerized isothiocyanate.…”

Section: Bidentate Ligand Systemsmentioning

confidence: 99%

“…Its reaction with CH 3 I gave a mixture of (P C3 P Me 3 )FeHI and (P C3 P Me 3 )FeI 2 . It was briefly mentioned that BH 3 ⋅ THF could react with (P C2 P Me 3 )FeH 2 to give (P C2 P Me 3 )FeH(BH 4 ) …”

Section: Tetradentate Ligand Systemsmentioning

confidence: 99%

“…The reactivity of (P C2 P Me 3 )FeH 2 under photochemical conditions or towards molecules containing polar double bonds (Figure ) very much resembles that of cis ‐(dmpe) 2 FeH 2 (Figures 12, 14, and 15). Photolysis of (P C2 P Me 3 )FeH 2 in toluene‐ d 8 was reported to yield a mixture of (P C2 P Me 3 )FeD( m ‐C 7 D 7 ) and (P C2 P Me 3 )FeD( p ‐C 7 D 7 ) . In contrast, photolysis of the propylene homolog (P C3 P Me 3 )FeH 2 in benzene or cyclohexane resulted in a cyclometalated product via activation of one of the methyl C−H bonds .…”

Section: Tetradentate Ligand Systemsmentioning

confidence: 99%

See 1 more Smart Citation

Iron Dihydride Complexes: Synthesis, Reactivity, and Catalytic Applications

Dai

Guan

2017

Israel Journal of Chemistry

View full text Add to dashboard Cite

Iron dihydride complexes often play important roles in catalytic reactions that employ reducing agents such as H 2 , boranes, and silanes. Development of more efficient and selective iron-based catalysts for these processes requires effective synthetic strategies and a deeper understanding of the reactivity of the dihydride complexes. The purpose of this review is to provide the readers with an overview of different ligand systems that have been used to support iron dihydride complexes. Figure 1. General reactivity of cis-and trans-FeH 2 beneficial to catalytic reduction.

show abstract

Where does Hydrogen Adsorb on Ru Nanoparticles? A Powerful Joint ²H MAS‐NMR/DFT Approach

et al. 2009

View full text Add to dashboard Cite

Several studies have shown that 2 H NMR, among many other techniques, is a versatile tool for the study of hydrogen coordination modes in transition metal complexes [1] or clusters.[2]Thanks to 1 H gas-phase and 2 H solid-state MAS-NMR spectroscopy, the coexistence of ancillary organic ligands, with mobile and reactive hydride ligands coordinated to ruthenium nanoparticles (NPs) has been observed.[3] Similar results were also found in the case of Ru NPs embedded in the cavities of metal-organic frameworks (MOFs).[4] However, secure assignment of the experimental information is hardly straightforward, as few reliable reference data are available for different bonding situations and chemical environments. As a matter of fact, solid-state NMR spectra of molecular compounds with nonequivalent deuterons generally consist of a complex superposition of subspectra with different shapes, which depend on the motion of the corresponding deuterons.[5] Here, the need for systematic theoretical studies for better interpretation of NMR spectra is clear.Recently, some of the authors have proposed the foundation of this work, with molecular density functional theory (DFT) calculations of quadrupole coupling constants Q cc and the asymmetry parameter h Q , (see the Supporting Information for definitions) of deuteron in ruthenium complexes [6] directly comparable with the experimental data.[1g] There is no doubt now that joint theoretical/experimental studies are a very powerful approach to complete the partial understanding of deuteron solid-state NMR spectra. Herein, we propose to explore the stability and to estimate quadrupole coupling parameters of deuterium atoms, on and below the surface of Ru NPs at low coverage, by means of DFT calculations on an infinite Ru(0001) slab surface model. Moreover, new quantitative insights into the kinetic behavior of chemically adsorbed hydrogen atoms are brought with the help of diffusion barrier estimations for surface hopping and subsurface paths. These investigations should form a first basis for the assignment of deuteron MAS-NMR spectra of ruthenium NPs.At a coverage value of 1/4 monolayer (ML), high-symmetry adsorption sites on the Ru surface, as depicted in Figure 1, were considered, yielding energetic and structural parameters in good agreement with the literature.[7] The Fcc site is slightly more stable than the Hcp site, while sites with less local symmetry order, namely On-top and Bridge, respectively lie 3 and 10 kcal mol À1 higher. Note that the terminal (On-top) and the two-fold (Bridge) sites are distinguished from the other sites by an imaginary frequency, which indicates that these states are saddle points at this particular low coverage value. The subsurface sites, Ts and Os, are significantly higher in energy, 24.2 and 8.7 kcal mol À1 respectively. Consequently, unless coverage increases significantly or co-adsorption species can reasonably invert their energy sign, there is a very low probability that hydrogen atoms can be found in these four-and six-fold sites at low co...

show abstract

A quantitative measure of the ionicity of selected iron hydride species by examination of the deuterium quadrupole coupling constant (DQCC)

Cited by 4 publications

References 27 publications

A Density Functional Theory Study of Spectroscopic and Thermodynamic Properties of Surfacic Hydrides on Ru (0001) Model Surface: The Influence of the Coordination Modes and the Coverage

A Density Functional Theory Study of Spectroscopic and Thermodynamic Properties of Surfacic Hydrides on Ru (0001) Model Surface: The Influence of the Coordination Modes and the Coverage

Iron Dihydride Complexes: Synthesis, Reactivity, and Catalytic Applications

Where does Hydrogen Adsorb on Ru Nanoparticles? A Powerful Joint ²H MAS‐NMR/DFT Approach

Contact Info

Product

Resources

About

A quantitative measure of the ionicity of selected iron hydride species by examination of the deuterium quadrupole coupling constant (DQCC)

Cited by 4 publications

References 27 publications

A Density Functional Theory Study of Spectroscopic and Thermodynamic Properties of Surfacic Hydrides on Ru (0001) Model Surface: The Influence of the Coordination Modes and the Coverage

A Density Functional Theory Study of Spectroscopic and Thermodynamic Properties of Surfacic Hydrides on Ru (0001) Model Surface: The Influence of the Coordination Modes and the Coverage

Iron Dihydride Complexes: Synthesis, Reactivity, and Catalytic Applications

Where does Hydrogen Adsorb on Ru Nanoparticles? A Powerful Joint 2H MAS‐NMR/DFT Approach

Contact Info

Product

Resources

About

Where does Hydrogen Adsorb on Ru Nanoparticles? A Powerful Joint ²H MAS‐NMR/DFT Approach