Diphenyl-2-pyridylphosphine is an organophosphorus compound with the formula P(C₆H₅)₂(2-C₅H₄N). It is the most widely used mono-pyridylphosphine ligand. Other mono-pyridylphosphines ligands (3-, 4-) are not common in chemical literature; however, tris-pyridylphosphines have been thoroughly investigated as ligands in transition metal complexes used for catalysis. Pyridylphosphines, including diphenyl-2-pyridylphosphine, may bind transition metals as monodentate or bidentate ligands4. Diphenyl-2-pyridylphosphine behaves as a P-bound monodentate ligand, or a P,N-bound bidentate ligand. Diphenyl-2-pyridylphosphine is a sought after ligand for its ability to relay protons to transition metals such as palladium(II) in

homogeneous catalysis In chemistry, homogeneous catalysis is catalysis by a soluble catalyst in a solution. Homogeneous catalysis refers to reactions where the catalyst is in the same phase as the reactants, principally in solution. In contrast, heterogeneous catalysi ...

Synthesis

Diphenyl-2-pyridylphosphine is prepared from 2-lithiopyridine with

chlorodiphenylphosphine Chlorodiphenylphosphine is an organophosphorus compound with the formula (C6H5)2PCl, abbreviated Ph2PCl. It is a colourless oily liquid with a pungent odor that is often described as being garlic-like and detectable even in the ppb range. It is u ...

: Diphenyl-2-pyridylphosphine is an integral ligand in the Pd(II) catalyzed carbonylation of alkynes. The pi-donor ability of one bidentate P,N-coordinated ligand is highly stabilizing to the metal center. While a second monodentate, N-protonated ligand transfers protons to the metal to be used in catalysis. The role of the pyridyl group in this catalytic cycle is evident when the ligand is replaced by triphenyl phosphine, and rates of catalysis a greatly decreased. This catalytic process is an important step in the production of polymers, and other fine chemicals. RC₂H + CO + XH + Pd cat → RCCH₂COX + RCHCHCOX Pd cat = Pd(OAc)₂/Ph₂PPy/ CH₃SO₃H R=alkyl, aryl X=OH, OR’, NR₂’ Scheme 1: Carbonylation of alkynes by cationic Pd(II) catalyst with a diphenyl-2-pyridylphosphine ligand.

Synthesis

References

Further reading