Diastereoselective coordination of racemic secondary phosphines (PHRR′) to Cu(I) precursors containing chiral bis(phosphines) (diphos*) was explored as a potential route to P-stereogenic phosphido complexes. Reaction of [Cu(NCMe) 7); two of the three expected isomers of the bis(secondary phosphine) complexes [Cu((R,R)i-Pr-DuPhos)(PhHP(CH 2 ) n PHPh)][PF 6 ] (n = 2 (8); n = 3 (9)) were formed preferentially in related reactions. Reaction of the halide-bridged dimers [Cu((R,R)-i-Pr-DuPhos)(X)] 2 or [Cu((R,R)-Me-FerroLANE)(I)] 2 with PHMe(Is) gave the labile adducts Cu((R,R)-i-Pr-DuPhos)(PHMe(Is))(X) (X = Cl (10), Br (11), I (12)) and Cu((R,R)-Me-FerroLANE)(PHMe-(Is))(I) (13). Complexes 1, 6, and 8−11 were structurally characterized by X-ray crystallography. Variable temperature NMR studies of 6 and 8 showed that the secondary phosphine ligands underwent reversible dissociation. Deprotonation of 6 or 7 generated the P-stereogenic phosphido complexes Cu(diphos*)(PMeIs) (diphos* = (R,R)-i-Pr-DuPhos ( 14) or (R,R)-Me-FerroLANE) (17)), observed by 31 P NMR spectroscopy, but decomposition also occurred. Density functional theory calculations were used to characterize the diastereomers of thermally unstable 17 and the inversion barrier in a model copperphosphido complex. These observations provided structure−property relationships which may be useful in developing catalytic asymmetric reactions involving secondary phosphines and P-stereogenic copper phosphido intermediates.