The orientation of the orthopalladation of iminophosphoranes R3P=NCH(2)Aryl (R = Ph, Aryl = Ph (1a), C6H4-2-Br (1b), C6H4-Me-2 (1e), C6H3-(Me)(2)-2,5 (1f); R = p-tolyl, Aryl = Ph (1c); R = m-tolyl, Aryl = Ph (1d); R3P = MePh2P, and Aryl = Ph (1g)) has been studied. la reacts with Pd(OAc)(2) (OAc = acetate) giving endo-[Pd(mu-Cl){C,N-C6H4(PPh2=NCH2Ph)-2}](2) (3a), while exo-[Pd(mu-Br){C,N-C6H4(CH2N=PPh3)-2}](2) (3b) could only be obtained by the oxidative addition of 1b to Pd-2(dba)(3). The endo form of the metalated ligand is favored kinetically and thermodynamically, as shown by the conversion of exo-[Pd(mu-OAc){C,N-C6H4(CH2N=PPh3)-2}](2) (2b) into endo[Pd(mu-OAc){C,N-C6H4(PPh2=NCH2Ph)-2}](2) (2a) in refluxing toluene. The orientation of the reaction is not affected by the introduction of electron-releasing substituents at the Ph rings of the PR3 (1c and 1d) or the benzyl units (1e and 1f), and endo complexes (3c-3f) were obtained in all cases. The palladation of MePh2P=NCH2Ph (1g) can be regioselectively oriented as a function of the solvent. The exo isomer [Pd(mu-Cl){C6H4(CH2N=PPh2Me)-2}](2) (exo-3g) is obtained in refluxing CH2Cl2, while endo-[Pd(mu-Cl){C,N-C6H4(PPh(Me)=NCH2Ph)-2}](2) (endo-3g) can be isolated as a single isomer in refluxing toluene. In this case, the exo metalation is kinetically favored while an endo process occurs under thermodynamic control, as shown through the rearrangement of [Pd(mu-OAc){C6H4(CH2N=PPh2Me)-2}](2) (exo-2g) into [Pd(mu-OAc){C,N-C6H4(P(Ph)Me=NCH2Ph)-2}](2) (endo-2g) in refluxing toluene. The preference for the endo palladation of 1a and the kinetic versus thermodynamic control in 1g has been explained through DFT studies of the reaction mechanism.