Fluxional chloro-pyrrole–Pd(ii) complex to cationic η2-pyrrole–Pd(ii) complex: subtlety in structure-directed bonding mode

Abstract

Fluxionality in η¹-aromatic carbocyclic-ligated Pd(II) complexes is retained if the η¹-carbon is replaced with an N atom through “hemilabile” palladium–carbon η¹-pyrrole ligation. Herein, we report and characterize a tetra-coordinated neutral chloro-pyrrole–Pd(II)-π-allyl complex, which shows dynamic behavior at room temperature. Upon chlorine abstraction by AgSbF₆, a cationic palladium complex is formed, where the coordination sphere of the metal is completed by the coordination of one CC double bond of the pyrrole ring. This cationic η²-pyrrole-ligated Pd(II)-π-allyl complex was characterized crystallographically. The coordination mode of the pyrrole in these isostructural complexes subtly changes with a change in carbon ligand (σ or π).