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.

Keywords: Keywords: dipalladium; crystal structures; doubly bridged; pyrimidinyl; pyrrolidinyldithiocarbamate; tris(pyrazoyl-1-yl)borate.