Dppe

dppe, short for 1,2-bis(diphenylphosphino)ethane, is a widely used bidentate phosphine ligand in coordination chemistry. It consists of two diphenylphosphino groups attached to a 1,2-ethane backbone, enabling the two phosphorus donor atoms to chelate a metal center. The ligand is typically represented as PPh2–CH2–CH2–PPh2. In metal complexes, dppe provides a relatively rigid, two-point attachment that often yields five-membered chelate rings and a bite angle near 90 degrees when bound to metals.

Properties and scope: dppe is a bulky, electron-rich ligand due to its phenyl substituents, which can stabilize low- and intermediate oxidation states of metals. It forms stable complexes with a range of transition metals, including palladium, rhodium, ruthenium, nickel, and platinum. The ligand’s steric and electronic characteristics influence catalysis through bite-angle effects and the surrounding steric environment around the metal center. dppe is commonly air-stable as a solid and is used in both laboratory and industrial contexts.

Applications: dppe is a staple ligand in homogeneous catalysis. It features prominently in palladium- and nickel-catalyzed cross-coupling reactions, hydrogenation, hydroformylation, and various other transformations. Representative complexes include PdCl2(dppe) and other M(dppe)X2 species, as well as Rh(dppe)(CO)2-type structures. As a well-characterized ligand, dppe serves as a benchmark for studying bite-angle effects and ligand design in catalytic systems.

Synthesis and availability: dppe can be prepared synthetically or purchased commercially. Typical routes involve coupling two phosphine units with an ethylene bridge, for example via reaction of diphenylphosphide sources with 1,2-dihaloethane, followed by purification. Its widespread availability and well-understood coordination chemistry contribute to its continuing popularity in organometallic research.