Reductively Stable Hydrogen-Bonding Ligands Featuring Appended CF2–H Units

Abstract

We present the development of ligands featuring the unconventional hydrogen bond donor, −CF₂H, within a metal’s secondary coordination sphere. When metalated with palladium, o-CF₂H-functionalized 1,10-phenanthroline provides highly directed H-bonding interactions with Pd-coordinated substrates. Spectroscopic and computational analyses with a series of X-type ligand acceptors (−F, −Cl, −Br, −OR) establish the H-bonding interaction strength for the −CF₂H group (∼3 kcal/mol). The synthesis of Pd⁰/Ni⁰ complexes and subsequent coupling (Ni) highlight the unique reductive and base compatibility of the −CF₂H hydrogen bond donor group.