London Dispersion‐Induced Contraction of the Cu─O Bond in Copper(I) Phenolates

Abstract

Abstract Conventional chemical wisdom holds that shorter bonds of a given type generally exhibit greater strength. Here, we reveal a counterintuitive bonding mode in copper(I) phenoxides, where bulky substituents induce Cu─O bond contraction without concomitant strengthening. X‐ray crystallographic analysis shows that increasing steric bulk at ortho positions of the phenolate ligand can shorten Cu─O bonds and promote symmetrical molecular geometries. Combined structural and computational studies demonstrate that London dispersion (LD) between N ‐heterocyclic carbene ligands and ortho ‐ tert ‐butyl phenolates plays a crucial role in driving this conformational reorganization. Local energy decomposition analysis quantifies substantial dispersion stabilization (by up to 11.2 kcal mol −1 ). Notably, natural orbital analysis indicates that the compressed Cu─O bonds exhibit diminished σ‐character despite enhanced π‐interactions. This LD‐induced bond contraction results in overall shorter yet weaker Cu─O bonds than those in less sterically bulk analogues, thereby establishing a different bonding paradigm from the conventional bond‐length/strength correlation.