The rate of' alkylutioii of' (2-N,N-diniethvlaniinophenvl)dipl?eiivlphospCii,ie with benzvl broinide in chlorofiwnz is faster than that of' the corresponding reuction of' (4-N ,N-diinethyluni inophenyl )diphenylphosphine. This result is disctissed in ternis o f u through-spucc N2,-P( IV) interaction for the fornier.The rule o/'ulkaliiie cleavage ofbe~izyl(4-N,N-diniethylaiiriiiophenvl)diphenylphosphoniuiii bromide, which gives toluene, is slower than the rate ofalkaline cleavage o/' l~eiizvl(2-N,N-diiiiethyluiiiinophenvl)diphenvlphosphoizitirii broniide, which gives dirnethvlaniline. This result is also discussed in ternis of' the t h rough-spuce N2 p-P( I V ) in teraction.The I'P N M R spectra of'a series ofortho-diineth-?iluinino-.suhstitirred triarylphosphines and benzyltriarylphosphoniunz halides show that the phosphorus utom is i m m shielded than in the corresponding para-diiiictlivlai~ii~io conipounds, as anticipated on the basis of.ui1 NZ,,-P(IV) interaction for the foriner.