Cyclopalladated compounds with a bidentate [C, N]/terdentate [C, N, S] benzylidenethiophene imine ligand. Crystal and molecular structures of [Pd{2,3-(MeO) 2C 6H 2C(H)NCH 2(C 4H 3S)}(μ-OAc)] 2, [Pd{2,3-(MeO) 2C 6H 2C(H)NCH 2(C 4H 3S)}(Cl)·(PPh 3)] and [{Pd[2,3-(MeO) 2C 6H 2C(H)NCH 2(C 4H 3S)](Cl)} 2(μ-Ph 2P(CH 2) 4PPh 2)

Abstract

Reaction of the Schiff base ligand 2,3-(MeO) 2C 6H 3C(H)NCH 2(C 4H 3S) ( 1), with palladium(II) acetate in toluene gave the dinuclear cyclometallated complex [Pd{2,3-(MeO) 2C 6H 2C(H)NCH 2(C 4H 3S)}(μ-OAc)] 2 ( 2), with the ligand bonded to the palladium atom through the imine nitrogen and the C6 carbon atom. The X-ray crystal structure of complex 2 is described. The reaction of 2 with aqueous sodium chloride gave the chloro-bridged complex [Pd{2,3-(MeO) 2C 6H 2C(H)NCH 2(C 4H 3S)}(μ-Cl)] 2 ( 3), after a metathesis reaction. Reaction of 3 with PPh 3 in acetone gave the mononuclear cyclometallated complex [Pd{2,3-(MeO) 2C 6H 2C(H)NCH 2(C 4H 3S)}(Cl)(PPh 3)] (4), in a bridge-splitting reaction. Treatment of 4 with silver triflate gave the cyclometallated complex [Pd{2,3-(MeO) 2C 6H 2C(H)NCH 2(C 4H 3S)}(PPh 3)][CF 3SO 3] ( 7), with the palladium atom bonded to four different atoms C, N, S and P. Reaction of 3 with the diphosphines dppp and dppb in a 1:1 molar ratio gave the dinuclear cyclometallated complexes [{Pd[2,3-(MeO) 2C 6H 2C(H)NCH 2(C 4H 3S)](Cl)} 2(μ-Ph 2P(CH 2) nPPh 2)] ( 5: n=3; 6: n=4), with the diphosphine bridging the two palladium atoms. The X-ray crystal structures of complexes 4 and 6 are reported.