417711-85-4Relevant academic research and scientific papers
Cyclopalladated compounds derived from [C,N,O] terdentate ligands: Synthesis, characterization and reactivity
Fernández, Alberto,Pereira, Esther,Fernández, Jesús J.,López-Torres, Margarita,Suárez, Antonio,Mosteiro, Roberto,Vila, José M.
, p. 39 - 48 (2008/10/08)
Treatment of the Schiff base ligands 2-ClC6H4C(H)=NCH2(C4 H7O) (a) and 3,4-(MeO)2C6H3C(H)=NCH2(C 4H7O) (b) with palladium(II) acetate in toluene or glacial acetic acid gave the dinuclear cyclometallated complexes [Pd{2-ClC6H3C(H)=NCH2(C4H 7O)}(μ-OAc)]2 (1a) and [Pd{3,4-(MeO)2C6H2C(H)=NCH2(C 4H7O)}(μ-OAc)]2 (1b) with the ligand bonded to the palladium atom through the imine nitrogen and the C6 carbon atom. The 1H and 13C-{1H} NMR spectra of the complexes show the occurrence in solution of three pairs of enantiomers. The acetato-bridged cyclometallated complex [Pd{3,4-(MeO)2C6H2C(H)=NCH2(C 4H7O)}(μ-OAc)]2 (1c) was prepared from the enantiopure ligand (R)-3,4-(MeO)2C6H3(H)= NCH2(C4H7O) (c). The NMR spectra of 1c showed the existence of only two diastereomers in the solution. The reaction of 1a and 1b with aqueous sodium chloride gave the chloro-bridged complexes [Pd{2-ClC6H3C(H)=NCH2(C4H 7O)}(μ-Cl)]2 (2a) and [Pd{3,4-(MeO)2C6H2C(H)=NCH2(C 4H7O)}(μ-Cl)]2 (2b) after a metathesis reaction. The reaction of 2a with PPh3 in acetone gave the mononuclear cyclometallated complex [Pd{2-ClC6H3C(H)=NCH2(C4H 7O)}(Cl)(PPh3)] (3a) in a bridge-splitting reaction. Treatment of 3a with silver triflate gave the cyclometallated complex [Pd{2-ClC6H3C(H)=NCH2(C4H 7O)}(PPh3)][CF3SO3] (4a) in which the palladium atom is bonded to four different atoms C, N, O and P. When complex 2a was reacted with silver triflate in acetone complex [Pd{2-ClC6H3C(H)=NCH2(C4H 7O)}((CH3)2CO)][CF3SO 3] (5a) was obtained with the ligand as [C,N,O] coordinated. The reaction of complexes 2a and 2b with the diphosphine dppp in a complex-phosphine 1:1 molar ratio gave the dinuclear cyclometallated complexes [{Pd[2-ClC6H3C(H)=NCH2(C4H 7O)](Cl)}2(μ-Ph2P(CH2) 3PPh2)] (8a) and [{Pd[3,4-(MeO)2C6H2C(H)=NCH2(C 4H7O)](Cl)}2(μ-Ph2P(CH 2)3PPh2)] (5b) with the diphosphine bridging the two palladium atoms. Reaction of complexes 2a and 2b with the phosphines dppp and cis-dppe in a 1:2 molar ratio gave the mononuclear complexes [Pd{2-ClC6H3C(H)=NCH2(C4H 7O)}{Ph2P(CH2)3Ph2-P, P}][ClO4] (6a), [Pd{3,4-(MeO)2C6H2C(H)=NCH2(C 4H7O)}{Ph2P(CH2)3Ph 2P,P}][ClO4] (3b) and [Pd{2-ClC6H2C(H)=NCH2(C4H 7O)}(cis-Ph2PCH=CHPh2-P,P)][Cl] (4b). The treatment of 2a with the triphosphine bis(2-diphenylphosphinoethyl)phenylphosphine in 1:2 molar ratio, followed by treatment with sodium perchlorate gave [Pd{3,4-(MeO)2ClC6H3C(H)=NCH2(C 4H7O)}{(PPh2CH2CH2) 2PPh-P,P,P}][ClO4] (7a) in which the palladium atom is bonded to the triphosphine through the three phosphorus atoms and to the Schiff base ligand through one carbon atom and the imine nitrogen.
