Syntheses, Reactivities, Characterization, and Crystal Structures of Dipalladium Complexes Containing the 1,3-pyrimidinyl Ligand: Structures of [Pd(PPh3)(Br)]2(μ,η2-C4H3N2)2, [Pd(Br)]2(μ,η2-Hdppa)2, and [{Pd(PPh3)(CH3CN)}2(μ,η2-C4H3N2)2][BF4]2

Abstract

In a refluxing chloroform solution, the η1-pyrimidinyl {pyrimidinyl = C4H3N2} palladium complex [Pd(PPh3)2(η1-C4H3N2)(Br)], 1 exhibited intermolecular displacement of two triphenylphosphine ligands to form the doubly bridged η2-pyrimidinyl Dipalladium complex [Pd(PPh3)(Br)]2(μ,η2-C4H3N2)2, 3. The treatment of 1 with Hdppa {Hdppa = N,N-bisdiphenyl phosphinoamine} in refluxing dichloromethane yielded the doubly bridged Hdppa dipalladium complex [Pd(Br)]2(μ,η2-Hdppa)2, 4. Complex 1 reacted with the bidentate ligand, NH4S2CNC4H8 and, NaS2COEt, and the tridentate ligand, KTp {Tp = tris(pyrazoyl-1-yl)borate}, to form the η2-dithio η1-pyrimidinyl complex [Pd(PPh3)(η1-C4H3N2)(η2-SS)], (5: SS = S2CNC4H8; 6: SS = S2COEt) and η2-Tp η1-pyrimidinyl complex [Pd(PPh3)(η1-C4H3N2)(η2-Tp)], 7, respectively. Treatment of 1 with AgBF4 in acetonitrile at room temperature resulted in the formation of the doubly bridged η2-pyrimidinyl dipalladium complex [{Pd(PPh3)(CH3CN)}2(μ,η2-C4H3N2)2][BF4]2, 8. All of the complexes were identified using spectroscopic methods, and complexes 3, 4, and 8 were determined using single-crystal X-ray diffraction analyses.