Nature of Cation‐π Interaction in Mono‐ and Inverted Sandwich Ga(I) Complexes. Insights Into the Ga(I)‐π Features and NMR Patterns from GaCp, GaCp*, [Ga₂Cp]⁺, and [Ga₂Cp*]⁺

Abstract

Cation‐π interactions involve different metallic cations, where the bonding characteristics depend on the involved species. Here, we unravel the interaction nature features for Ga(I)‐π interactions, where different contributing terms ensure an efficient coordination of one and two Ga(I)‐atoms towards a common aromatic ring. Our results show a more balanced contribution of about ~70% from electrostatic character and of ~30% from orbital interaction for the prototypical GaCp, GaCp*, [Ga2Cp]+ and [Ga2Cp*]+ species. Such description strongly contrasts with the highly electrostatic character in alkali and alkaline‐earth metals counterparts. The variation from mono to inverted sandwich complexes leads to a decrease in the interaction energy from ‐180.9 to ‐148.1 kcal/mol for Cp based species, and from ‐184.4 to ‐155.5 kcal/mol in Cp* counterparts, owing to a decrease in both electrostatic and orbital stabilizing contributions. Thus, the aromatic rings exhibit coordination versatility towards one or two Ga(I) cations, retaining a sizable stabilization of the Ga(I)‐π interaction. Thus, cation‐π interactions are able to exhibit different types according to the involved metal cation, which relies on a more electrostatic/orbital balanced interaction, which serves to evaluate further mono and inverted sandwich complexes sharing a common aromatic ring.