A comparative study of the chelating ability of the -N(R)-(CH2)n-CO-N(R)2 framework in σ-aryl palladium(II) complexes derived from 2-iodoanilines and 2-iodobenzylamines.: Synthesis of new types of terdentate [C,N,O] Pd(II) complexes and C,N-bridged binuclear Pd(II) compounds

The reaction of iodo anilines 2-[C6H4-N(Me)-CH2-CO-N(R)(2) (R = Me, 1a; R = Et, 1b) with Pd-2(dba)(3) afforded binuclear Pd(II) complexes [Pd{eta-(N,C)-mu-N(Me)(C6H4-2)CH2C(O)N(R)(2)}I](2) (R = Me, 2a; R = Et, 2b), which by reaction with PPh3 and TI(TfO) were transfortned into the cationic binuclear Pd(II) complexes [Pd{eta-(N,C)-mu-N(Me)(C6H4-2)CH2C(O)N(R)(2)}(PPh3)](2)2TfO (R = Me, 3a; R = Et, 3b). On the contrary, the reaction of aniline 2-I-4-MeC6H3-N(Me)-CH2CH2-CO-N(Me)(2) (4) with Pd-2(dba)(3) and PPh3 afforded four-membered azapalladacycle [Pd{kappa C-2,N-4-MeC6H3{N(Me)CH2CH2C(O)N(Me)(2)}-2}(PPh3)] (5), which on treatment with TI(TfO) did not yield a complex with the ligand in a C,N,O-terdentate fashion, the unstable Pd(II) complex [Pd{kappa C-2,N-4-MeC6H3{N(Me)CH2CH2C(O)N(Me)(2)}-2}OTf(PPh3)} (6) being obtained instead. On the other hand, 2-IC6H4-CH2-N(Bn)-CH2)-CO-N(Me)(2) (7) reacted with Pd-2(dba)(3) to give the C,N,O-terdentate complex [Pd{kappa C-3,N,O-C6H4{CH2N(Bn)-CH2C(O)N(Me)(2)}-2}I] (8), which by reaction with PPh3 and TI(TfO) was transformed into the cationic CNO-terdentate complex [Pd{kappa C-3,N,O-C6H4{CH2N(Bn)CH2C(O)N(Me)(2)}-2](PPh3)]TfO (9). Similarly, treatment of iodo benzylamines 2-IC6H4-CH2-N(R)-CH2CH2-CO-N(Me)(2) (R = Bn, 10a; R = Me, 10b) with Pd-2(dba)(3) and then with PPh3 and TI(TfO) afforded cationic C,N,O-terdentate complexes [Pd{kappa C-3,N,O-C6H4{CH2N(R)CH2CH2C(O)N(Me)(2)}-2}(PPh3)]TfO (R = Bn, 12a; R = Me, 12b). Solid-state structures of palladium complexes 2a, 2b, 3a center dot C6H6 center dot 3THF, and 8 have been determined by X-ray analysis.