1 research outputs found
Chelate Palladium(II) Complexes with Saturated <i>N</i>‑Phosphanyl-N-Heterocyclic Carbene Ligands: Synthesis and Catalysis
<i>N</i>-Phosphanyl-N-heterocyclic
carbenes (NHCPs) featuring
a saturated imidazolin-2-ylidene or tetrahydropyrimid-2-ylidene ring
have been synthesized and characterized. The free carbenes exhibit
good stability and can be stored in the solid state for months at
ambient temperature without decomposition. Contrary to imidazoline-based
NHCPs, which decompose by ring opening, <i>N</i>-phosphanylÂtetrahydropyrimid-2-ylidenes
isomerize to 2-phosphanyl tetrahydropyrimidines upon heating. The
free carbenes are capable of acting as chelating ligands toward palladiumÂ(II),
forming very stable mononuclear complexes that have been structurally
characterized. The catalytic potential of the complexes has been preliminarily
assessed in cross-coupling reactions, most notably in the Suzuki coupling
of aryl chlorides, where these complexes display promising activity,
and in the copper- and amine-free Sonogashira coupling of aryl bromides