Synthesis and Structure of Binuclear Cyclometalated Pd(II) Complexes with Aliphatic Carboxylic Acids

A series of binuclear cyclometalated carboxylate-bridge palladium(II) complexes of general formula [(2-phpy)Pd(OOCR)]2, where R = Et (V), n-Pr (VI), and n-Bu (VII), has been synthesized. Bimetallic complex [PdNi(OOCMe)4] (I) has been used as a reactive precursor. At the first stage, a metathesis reaction of complex I with aliphatic carboxylic acids (propionic, butyric, and valeric) was carried out to form intermediate heterometallic compounds of the type [PdNi(OOCR)4] (II–IV). At the second stage, their reaction with 2-phenylpyridine (2-phpy) leads to ortho-metalation and the formation of the target binuclear cyclometalated complexes V–VII in high yields. Molecular structures of complexes V–VII have been determined by X-ray diffraction analysis (CIF files CCDC no. 2425979 (V), 2425980 (VI), 2425981 (VII)).