Domenico Gioffrè

Last Name

Gioffrè

First Name

Domenico

ORCID

0000-0003-2208-4148

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03872 - Copéret, Christophe / Copéret, Christophe

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Publications 1 - 10 of 13

Grafting of Group-10 Organometallic Complexes on Silicas: Differences and Similarities, Surprises and Rationale
Gioffrè, Domenico; Rochlitz, Lukas; Payard, Pierre-Adrien; et al. (2022)
Helvetica Chimica Acta
Surface organometallic chemistry (SOMC) represents a unique synthetic platform for the preparation of model heterogeneous catalysts resembling those broadly applied in industry. SOMC techniques usually rely on the grafting of tailored molecular precursors onto the surface OH groups of oxide supports. The development of such precursors and the understanding of their reactivity with the supports are therefore crucial for the development of well-defined surface species. While a large number of organometallic precursors of early transition metals are known, only few examples of group-10 metal complexes are reported, in spite of the great interest for heterogeneous catalysts based on the Pt-group elements. Herein, we report the reactivity of a family of group-10 (Ni, Pd and Pt) alkyl complexes, towards partially dehydroxylated SiO2 yielding well-defined supported species. We studied the effect of the metal, ligand, and support on the grafting mechanism of such precursors through a combined experimental and computational approach. Ultimately, we showed that at least two grafting pathways are possible for these compounds, namely the protonolysis of the M-alkyl bond by surface OH groups and the opening of strained siloxane bridges: the proportion of the two depending on the nature of the metal and its ancillary ligand.
Solid-state NMR spectra of protons and quadrupolar nuclei at 28.2 T: Resolving signatures of surface sites with fast magic angle spinning
Berkson, Zachariah J.; Björgvinsdóttir, Snædís; Yakimov, Alexander; et al. (2022)
JACS Au
Advances in solid-state nuclear magnetic resonance (NMR) methods and hardware offer expanding opportunities for analysis of materials, interfaces, and surfaces. Here, we demonstrate the application of a very high magnetic field strength of 28.2 T and fast magic-angle-spinning rates (MAS, >40 kHz) to surface species relevant to catalysis. Specifically, we present as case studies the 1D and 2D solid-state NMR spectra of important catalyst and support materials, ranging from a well-defined silica-supported organometallic catalyst to dehydroxylated γ-alumina and zeolite solid acids. The high field and fast-MAS measurement conditions substantially improve spectral resolution and narrow NMR signals, which is particularly beneficial for solid-state 1D and 2D NMR analysis of 1H and quadrupolar nuclei such as 27Al at surfaces.
Probing the Nature of Surface Hydrides by Deuterium Quadrupolar Parameters: A Case Study on Silica-Supported Zirconium Hydrides
Docherty, Scott R.; Schärz, Philipp; Gioffrè, Domenico; et al. (2024)
Helvetica Chimica Acta
Supported metal hydrides are key reactive intermediates in various catalytic processes, such as hydrogenation and dehydrogenation, but are often challenging to characterize spectroscopically. Here, deuterium solid state nuclear magnetic resonance spectroscopy is used to understand the structure of the corresponding silica-supported zirconium hydrides after H/D exchange as an illustrative example of supported metal hydrides, which have been shown to display notable reactivity towards small molecules (e. g., CO₂ and N₂O) and to activate both C−H and C−C bonds, hence their use in to the conversion of hydrocarbons (alkanes, polyolefins etc.)
Molecular and Electronic Structure of Isolated Platinum Sites Enabled by the Expedient Measurement of 195Pt Chemical Shift Anisotropy
Venkatesh, Amrit; Gioffrè, Domenico; Atterberry, Benjamin A.; et al. (2022)
Journal of the American Chemical Society
Techniques that can characterize the molecular structures of dilute surface species are required to facilitate the rational synthesis and improvement of Pt-based heterogeneous catalysts. 195Pt solid-state NMR spectroscopy could be an ideal tool for this task because 195Pt isotropic chemical shifts and chemical shift anisotropy (CSA) are highly sensitive probes of the local chemical environment and electronic structure. However, the characterization of Pt surface-sites is complicated by the typical low Pt loadings that are between 0.2 and 5 wt% and broadening of 195Pt solid-state NMR spectra by CSA. Here, we introduce a set of solid-state NMR methods that exploit fast MAS and indirect detection using a sensitive spy nucleus (1H or 31P) to enable the rapid acquisition of 195Pt MAS NMR spectra. We demonstrate that high-resolution wideline 195Pt MAS NMR spectra can be acquired in minutes to a few hours for a series of molecular and single-site Pt species grafted on silica with Pt loading of only 3-5 wt%. Low-power, long-duration, sideband-selective excitation, and saturation pulses are incorporated into t1-noise eliminated dipolar heteronuclear multiple quantum coherence, perfect echo resonance echo saturation pulse double resonance, or J-resolved pulse sequences. The complete 195Pt MAS NMR spectrum is then reconstructed by recording a series of 1D NMR spectra where the offset of the 195Pt pulses is varied in increments of the MAS frequency. Analysis of the 195Pt MAS NMR spectra yields the 195Pt chemical shift tensor parameters. Zeroth order approximation density functional theory calculations accurately predict 195Pt CS tensor parameters. Simple and predictive orbital models relate the CS tensor parameters to the Pt electronic structure and coordination environment. The methodology developed here paves the way for the detailed structural and electronic analysis of dilute platinum surface-sites.
A Molecular Analogue of the C−H Activation Intermediate of the Silica-Supported Ga(III) Single-Site Propane Dehydrogenation Catalyst: Structure and XANES Signature
Rochlitz, Lukas; Searles, Keith; Nater, Darryl; et al. (2021)
Helvetica Chimica Acta
Propane dehydrogenation is an important field of research due to an increasing world-wide demand of propene while classical production routes through naphtha cracking are in decline. In that context, silica-supported Ga(III) sites, synthesized from surface organometallic chemistry principles, show high selectivity and stability in the propane dehydrogenation reaction. This performance is in significant contrast to the reported fast deactivation and lower selectivity of most Ga2O3 and CrO3 based materials. The Ga-catalyzed propane dehydrogenation reaction is proposed to proceed through the formation of Ga alkyl intermediates for which it would be desirable to have detailed structural and spectroscopic information. Here, we prepare a consistent series of Ga(III) molecular complexes with varying numbers of alkyl and siloxide ligands; they are characterized by single crystal X-Ray diffraction and X-Ray Absorption Near Edge Structure analysis, which is known to be highly sensitive to the Ga coordination environment. We report in particular the structure and the spectroscopic signatures of [Ga(iPr)(OSi(OtBu)3)2(HOSi(OtBu)3)], a molecular mimic of the key proposed reaction intermediates in the Ga-catalyzed PDH reaction.
Natural abundance ¹⁹⁵Pt-¹³C correlation NMR spectroscopy on surfaces enabled by fast MAS dynamic nuclear polarization
Wang, Zhuoran; Robinson, Thomas C.; Gioffrè, Domenico; et al. (2024)
Journal of Magnetic Resonance Open
Surface organometallic chemistry has developed as an effective strategy for the rational design and synthesis of well-defined, single-site Pt-based heterogeneous catalysts. Given its high sensitivity to changes in electronic structure, ¹⁹⁵Pt solid-state NMR spectroscopy offers a unique approach to investigate the chemical structure and local environment of Pt surface sites, providing invaluable insights for establishing structure-activity relationships. However, this approach is typically hindered by severe sensitivity issues, due to the low loading of Pt sites and the often-encountered large ¹⁹⁵Pt chemical shift anisotropies. To overcome this limitation, ¹⁹⁵Pt NMR signature of surface metal centers can be indirectly detected through protons. Indirect detection on ¹³C spins, has also been demonstrated to be feasible by combining isotopic labeling with dynamic nuclear polarization (DNP). Here, we extend this methodology to a supported Pt complex at natural abundance. The material was prepared by grafting (COD)PtMeOSi(OtBu)₃ (COD = 1,5-cyclooctadiene, Me = methyl and tBu = tert‑butyl) onto partially dehydroxylated silica. DNP enhanced two-dimensional through-bond ¹³C{¹⁹⁵Pt} heteronuclear correlation experiments were successfully implemented at fast magic angle spinning. They enabled the detection of the 0.37 % NMR-responsive surface species, thereby showcasing the remarkable sensitivity of this approach and its broad applicability. Key bonding information was obtained by measuring the correlated ¹³C and ¹⁹⁵Pt isotopic chemical shifts as well as ¹J(¹³C-¹⁹⁵Pt) coupling constants, confirming directly the coordination structure of the surface Pt sites.
²H Quadrupolar Coupling Constant: A Spectroscopic Ruler for Transition Metal-Hydride Bond Distances in Molecular and Surface Sites
Gioffrè, Domenico; Müller, Cäcilie; Docherty, Scott; et al. (2025)
Journal of the American Chemical Society
Transition metal hydrides (TMHs) find numerous applications across fields from catalysis to H2 storage. Yet, determining the structure of TMHs can remain a challenge, as hydrogen is difficult to detect by X-ray based or classical spectroscopic techniques. Considering that the deuterium isotope (D) is a quadrupolar nucleus (I = 1) and that a quadrupolar coupling constant (CQ) depends on the distance between D and its bonding partner E (dED), we evaluate this trend across molecularly defined transition metal deuterides (TMDs) through a systematic investigation across TM block elements using both computations and experiments. We show that the M–D bond distance (dMD) in [Å] correlates with the CQ values in [kHz] as dMD = 7.83(CQ + 28.7)−1/3─independently from the nature of the TM─with an accuracy >0.04–0.08 Å. Based on experimental CQ values measured by 2H solid-state NMR, this simple correlation is then used to obtain the M–D bond distances in two silica-supported TMDs (M = Zr and Ir), notable heterogeneous catalysts representing early and late TMDs, where evaluating M–D bond distances by other means is very challenging. Considering the ease of measurement, this method is readily applicable to a large range of diamagnetic terminal M–Ds, from molecular to surface sites, making 2H NMR a method of choice to measure TMD bond distances.
¹³C Chemical Shift of N-Heterocyclic Carbenes in Coinage Metal(I) Complexes and Clusters: trans-Influence and Spin-Orbit Coupling
Dery, Shahar; Ehinger, Christian; Roudin, Jeremy; et al. (2025)
Journal of the American Chemical Society
N-Heterocyclic carbenes (NHCs) are versatile ligands in organometallic chemistry, prized for their strong σ-donating and tunable electronic properties. They are used to stabilize a wide range of motifs, including clusters and nanoparticles, based in particular on coinage metals─Cu, Ag, and Au. Notably, the carbene ¹³C NMR isotropic chemical shift (δiso) of NHC-coinage metal complexes varies significantly across these elements, reflecting the nuanced interplay of electronic and structural factors. Here, we study the carbene carbon chemical shift in NHC-Au(I)-X complexes (X = H, OH, halides, CN, N₃, and neutral ligands such as pyridine and NHC) compared to the Cu and Ag congeners. Density functional theory calculations are used to analyze the chemical shielding tensor components, revealing that stronger σ-donor X-ligands lead to greater deshielding of δiso through enhanced paramagnetic contributions and, for Au, spin–orbit contributions of comparable magnitude. Moreover, a correlation between the spin–orbit contribution to the chemical shift (σso) and the Au-carbene bond distance highlights the critical role of trans-influence in modulating spin–orbit coupling and the overall chemical shift. Analysis of σso shows that stronger σ-donor ligands, associated with a greater trans-influence and elongated Au-carbene bond, lead to a higher-lying NHC-Au σ-bond and lower-lying π*-orbital, ultimately yielding greater deshielding and higher ¹³C chemical shift. This work provides insight into how structural and electronic factors govern carbene chemical shifts in NHC-based Au complexes and clusters, establishing a direct link between NMR spectroscopic descriptors and electronic structure, thus opening avenues for developing structure–activity relationships in catalysis and materials science.
Classification and Identification of Facet- and Edge-Specific γ-Al2O3 Surface Sites from 1H/27Al NMR Cross-Signatures and DFT Modeling
Gioffrè, Domenico; Florian, Pierre; Pigeon, Thomas; et al. (2025)
Journal of the American Chemical Society
NMR Signatures of Transition-Metal Nuclei: From Local Environments and Electronic Structures to Reactivity Descriptors in Molecular and Heterogeneous Catalysis
Berkson, Zachariah J.; Cao, Weicheng; Gioffrè, Domenico; et al. (2025)
JACS Au
This Perspective summarizes the current state of the art in understanding the local environments of metal sites across homogeneous and heterogeneous catalysts by means of solid-state nuclear magnetic resonance (NMR), augmented with first-principles density functional theory (DFT) calculations, focusing on transition-metal nuclei and emphasizing the potential of this approach for understanding reactivity. We illustrate in particular how NMR parameters of transition-metal nuclei provide unique insights into the electronic structures and coordination environments of metal sites, complementary to information that can be obtained from ¹³C, ¹⁵N, or ¹⁷O NMR parameters of metal-bound ligands. Using the examples of solid-state NMR analyses of supported and molecular systems containing NMR-active transition-metal nuclei (⁹⁵Mo, ¹⁹⁵Pt, ¹⁰⁹Ag, ¹⁸³W, ⁵¹V, and 47/49Ti), we show how NMR parameters can be determined and related to structural and electronic features of molecular and surface metal sites. Moreover, analyzing the origins of the chemical shift tensors of these metal nuclei through DFT computations helps to connect NMR signatures to specific local coordination environments and electronic structures (frontier molecular orbitals) and the corresponding reactivity of specific metal sites, thereby opening the possibility of establishing structure–activity relationships across catalytic systems, including industrially relevant heterogeneous catalysts.

Publications 1 - 10 of 13

Domenico Gioffrè

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