Crystals of the title compound, C(30)H(20)F(12)P(2) or R(2)PCH(2)CH(2)PR(2) (R = 4-C(6)H(4)CF(3)), were inadvertently prepared while attempting to recrystallize a crude sample of trans-Re(Cl)(N(2))(R(2)PCH(2)CH(2)PR(2))(2) from diethyl ether. The molecule lies on a center of inversion. One of the rings lies approximately in the P-C-C-P plane; the dihedral angle is 174.53°.The other ring is not quite perpendicular; the dihedral angle is 71.1°. The compound is isostructural with the R = Ph, 4-C(6)H(4)CH(3) and 4-C(6)H(4)CH(2)CH(3) analogues. It is well known that the basicity of phosphines and diphosphines can be altered by changing the electron-donating ability of R; however, the structural parameters for the title compound do not significantly differ from those of the aforementioned substituted-phenyl compounds.