Tris(2-cyanoethyl)phosphine is commonly used as a reducing reagent in organic synthesis.

 A Procedure for Quantitative Determination of Tris(2-Carboxyethyl)phosphine, an Odorless Reducing Agent More Stable and Effective Than Dithiothreitol. [1]

  Neutral Chalcogenide Tungsten Cluster with Tris(2-Cyanoethyl)phosphine. [2]

 References:

[1] J.Han, et al, Anal. Biochem., 1994, 220(1), pp 5-10.

[2] A.D.Gassan, et al, Eur. J. Inorg. Chem., 2020, https://doi.org/10.1002/ejic.202000418.