Orbital Decomposition of the Carbon Chemical Shielding Tensor in Gold(I) N-Heterocyclic Carbene Complexes.
The good performance of N‐heterocyclic carbenes (NHCs), in terms of versatility and selectivity, has called the attention of experimentalists and theoreticians attempting to understand their electronic properties. Analyses of the Au(I)–C bond in [(NHC)AuL]+/0 (L stands for a neutral or negatively charged ligand), through the Dewar–Chatt–Duncanson model and the charge displacement function, have revealed that NHC is not purely a σ‐donor but may have a significant π‐acceptor character. It turns out, however, that only the σ‐donation bonding component strongly correlates with one specific component of the chemical shielding tensor. Here, in extension to earlier works, a current density analysi…
Donation and back-donation in cis- and trans-[(η5-C5H5)Fe(η1-CO)(μ-CO)]2 tautomers: Which relative is more generous? An ETS-NOCV bond analysis
The ETS-NOCV bond analysis has been exploited to quantitatively estimate donation and back-donation properties of [(η5-C5H5)]−, CO, and FeI in the cis-/trans-[(η5-C5H5)Fe(η1-CO)(μ-CO)]2 (cis-I/trans-I) tautomers. Theoretical outcomes indicate that the Fe-CO bond, regardless to the CO monoapto (η1-) or bridging (μ-) coordination, has a sizeable π Fe → CO back-bonding contribution, which is stronger in trans-I than in cis-I. Moreover, [(η5-C5H5)]− has the weakest back-donation acceptor capability. The back-bonding behaviour of the Fe → η1-CO interaction well agrees with the experimental symmetric/antisymmetric infrared νCO (sνηjavax.xml.bind.JAXBElement@fc12185-CO/aνηjavax.xml.bind.JAXBElemen…