CH-π and CF-π Interactions Lead to Structural Changes of N-Heterocyclic Carbene Palladium Complexes

The role of CH–π and CF–π interactions in determining the structure of N‐heterocyclic carbene (NHC) palladium complexes were studied using 1H NMR spectroscopy, X‐ray crystallography, and DFT calculations. The CH–π interactions led to the formation of the cis‐anti isomers in 1‐aryl‐3‐isopropylimidazol‐2‐ylidene‐based [(NHC)2PdX2] complexes, while CF–π interactions led to the exclusive formation of the cis‐syn isomer of diiodobis(3‐isopropyl‐1‐pentafluorophenylimidazol‐2‐ylidene) palladium(II). Doing the twist: The roles of CH–π and CF–π interactions in determining the structure of the title complexes were studied. The CH–π interactions led to the cis‐anti isomers in 1‐aryl‐3‐isopropylimidazol‐2‐ylidene‐based complexes, while CF–π interactions led to the exclusive formation of the cis‐syn isomer of diiodobis(3‐isopropyl‐1‐pentafluorophenylimidazol‐2‐ylidene)palladium(II). C gray, N violet, Pd turquoise, F yellow, I purple.