Related Experiment Video
Updated: May 2, 2026
Spin Saturation Transfer Difference NMR SSTD NMR: A New Tool to Obtain Kinetic Parameters of Chemical Exchange Processes
Published on: November 12, 2016
13C Chemical Shift of N-Heterocyclic Carbenes in Coinage Metal(I) Complexes and Clusters: trans-Influence and
Shahar Dery1, Christian Ehinger1, Jeremy Roudin1
1Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich CH-8093, Switzerland.
Abstract:
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.
More Related Videos
16:11Thermochemical Studies of NiII and ZnII Ternary Complexes Using Ion Mobility-Mass Spectrometry
Published on: June 8, 2022
10:52Line Shape Analysis of Dynamic NMR Spectra for Characterizing Coordination Sphere Rearrangements at a Chiral Rhenium Polyhydride Complex
Published on: July 27, 2022
Related Concept Videos
02:58Properties of Transition Metals
02:34Structural Isomerism
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly,...
02:52Stereoisomerism
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
00:52¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
01:17Spin–Spin Coupling: One-Bond Coupling
01:20Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...