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Ferrocene-Based Pincer Complexes of Palladium: Synthesis, Structures, and Spectroscopic and Electrochemical Properties

2004; American Chemical Society; Volume: 23; Issue: 20 Linguagem: Inglês

10.1021/om0497285

1520-6041

Avthandil A. Koridze, Sergey A. Kuklin, Aleksey M. Sheloumov, F.M. Dolgushin, V.Yu. Lagunova, I. Yu. Petukhova, M.G. Ezernitskaya, Аlexander S. Peregudov, P. V. Petrovskii, E.V. Vorontsov, Miguel Baya, Rinaldo Poli,

Catalytic Cross-Coupling Reactions

Palladium P,C,P pincer complexes based on ferrocene were synthesized for the first time. The reaction of the 1,3-bis((dialkylphosphino)methyl)ferrocenes {1,3-(R2PCH2)2C5H3}Fe(C5H5) (2a, R = Pri; 2b, R = But) with PdCl2(NCPh)2 in refluxing 2-methoxyethanol leads to the corresponding pincer complexes PdCl[{2,5-(R2PCH2)2C5H2}Fe(C5H5)] (3a,b). The ferrocene-based binuclear compound 3b reacts with [Cp2Fe]PF6 to form the ferrocenium-based pincer complex {PdCl[{2,5-(But2PCH2)2C5H2}Fe(C5H5)]}PF6 (4b), and this is the first example of ferrocene-based phosphine chelate oxidation centered on the iron atom. Treatment of complexes 3a,b with NaBH4 in refluxing ethanol affords the complexes Pd(BH4)[{2,5-(R2PCH2)2C5H2}Fe(C5H5)] (5a, R = Pri; 5b, R = But), containing a BH4− group coordinated to the metal in the rarely occurring unidentate mode. The structures of 3a,b and 5b were confirmed by X-ray analyses. Cyclic voltammetric investigations of complexes 2b and 3a,b are also reported. The structural and spectroscopic features of the palladium ferrocene-based pincer complexes are discussed and compared with those of related compounds.