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

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.