Tricyclohexylphosphine Explained

Tricyclohexylphosphine is the tertiary phosphine with the formula P(C₆H₁₁)₃. Commonly used as a ligand in organometallic chemistry, it is often abbreviated to PCy₃, where Cy stands for cyclohexyl. It is characterized by both high basicity (pK_a = 9.7)^[1] and a large ligand cone angle (170°).^{[2] [3]}

Important complexes containing P(Cy)₃ ligands include the 2005 Nobel Prize-winning Grubbs' catalyst and the homogeneous hydrogenation catalyst Crabtree's catalyst.

References

1. C. A.. Streuli. Determination of Basicity of Substituted Phosphines by Nonaqueous Titrimetry. Anal. Chem.. 1960. 32. 8 . 985–987. 10.1021/ac60164a027.
2. R. C. . Bush . R. J. . Angelici . Phosphine basicities as determined by enthalpies of protonation . 1988 . . 27 . 4 . 681–686 . 10.1021/ic00277a022.
3. Immirzi . A. . Musco . A. . A Method to Measure the Size of Phosphorus Ligands in Coordination Complexes . 10.1016/S0020-1693(00)95635-4 . 1977 . Inorg. Chim. Acta . 25 . L41–42.