Английская Википедия:Diphenyl-2-pyridylphosphine

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Diphenyl-2-pyridylphosphine is an organophosphorus compound with the formula P(C6H5)2(2-C5H4N). It is the most widely used mono-pyridylphosphine ligand.[1] 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.[2]

Synthesis

Diphenyl-2-pyridylphosphine is prepared from 2-lithiopyridine with chlorodiphenylphosphine:[3]

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.[4] While a second monodentate, N-protonated ligand transfers protons to the metal to be used in catalysis.[4] 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.[3]

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.

References

Шаблон:Reflist

Further reading