Palladium Complexes with Metallocene-Bridged Bidentate Diphosphine Ligands: Synthesis, Structure, and Catalytic Activity in Amination and Cross-Coupling Reactions

The syntheses and characterization of series of new metallocene-bridged diphosphines and the structures
of complexes of some of them with Pd(II) are reported. These complexes were examined as the catalysts
in amination reactions of halogenoarenes and in the Suzuki reaction. The complexes based on ruthenocene
(2) and osmocene (3) showed lower activities then the palladium complex with dppf in amination reactions
and the same activities in the Suzuki reaction. New palladium complexes with the bidentate bulky and
electron-rich ligands Fe(η5-C5H4P(o-PriC6H4)2)2 (6) and Fe(η5-C5H4P(o-MeOC6H4)2)2 (5) showed a very
high catalytic activity in amination and Suzuki coupling of aryl bromides. A complex with ligand 6 was
used in the amination of 4-bromotoluene by primary and secondary amines and showed excellent activity.

本文报道了一系列新型茂金属桥联二膦配体的合成与表征，以及其中部分配体与Pd(II)形成的配合物的结构。将上述配合物作为催化剂，应用于卤代芳烃的胺化反应与铃木（Suzuki）反应中。相较于基于1,1'-双(二苯基膦基)二茂铁（dppf）的钯配合物，基于钌茂（2）和锇茂（3）的配合物在胺化反应中催化活性更低，而在铃木反应中二者活性相当。针对双齿位阻型富电子配体Fe(η⁵-C₅H₄P(o-异丙基苯基)₂)₂（6）与Fe(η⁵-C₅H₄P(o-甲氧基苯基)₂)₂（5）所制备的新型钯配合物，在芳基溴化物的胺化反应与铃木偶联反应中展现出极高的催化活性。以配体6制备的配合物应用于伯胺与仲胺参与的4-溴甲苯胺化反应，同样表现出优异的催化活性。