Influence of the Ligand Backbone in Pincer Complexes: Indenediide-, Indolyl-, and Indenyl-Based SCS Palladium Complexes

A new pincer ligand featuring an indolyl backbone was prepared and coordinated to palladium. The properties of related indenediide-, indenyl-, and indolyl-based complexes have been compared by spectroscopic and structural means. Modulation of the ligand backbone was shown to significantly influence the electron density at Pd. Its impact on catalytic performance has been illustrated in the Pd-catalyzed imine allylation. The higher the electron density at Pd, the more active the SCS pincer complex.