Comparative Oxidative Addition of Transition-Metal Iodocyclopentadienyl Complexes (η⁵-C₅H₄-I)ML_n (M = Re, Mn, Fe) with a Palladium(0) Complex:  Relevance to the Efficiency of Catalytic Reactions

Abstract

The rate constants of the oxidative addition of the transition-metal iodocyclopentadienyl complexes (η5-C5H4-I)MLn (ML n = Mn(CO)3 (1a), Re(CO)3 (1b), CpFe (1c)) with Pd0(PPh3)4 have been determined in DMF. As expected, the oxidative addition is faster for the electron-acceptor groups Mn(CO)3 and Re(CO)3 than for the electron-donor group FeCp, with the reactivity order 1a > 1b ≫ 1c. Comparison of the rate constants of the oxidative additions affords a new strategy for the evaluation of the electronic properties of transition-metal units ligated to the iodocyclopentadienyl moiety with the following decreasing electron-acceptor properties: Mn(CO)3 > Re(CO)3 ≫ FeCp. The complexes formed in the oxidative addition are characterized as trans-[(η5-C5H4)PdI(PPh3)2]ML n (ML n = Mn(CO)3 (2a), Re(CO)3 (2b), CpFe (2c)) with the decreasing stability order in DMF: 2c ≫ 2b > 2a. The relevance to the efficiency of palladium-catalyzed Stille or Sonogashira reactions from related complexes 1 is discussed.

Substituent Effects on Stoichiometric and Catalytic Cleavage of Carbon–Nitrogen Bonds in Aniline Derivatives by Ruthenium–Phosphine Complexes

“…The substituent effect on the C–N bond cleavage was not cleanly correlated with the Hammett substituent constants, but the electron-donating substituent, such as OMe and Me groups, increased the reactivity of the C–N bonds. Therefore, the subsitutent effect observed here on the C–N bond cleavage is opposite to that of Wolczanski’s tantalum-mediated C–N bond cleavage and the general tendency of oxidative addition of polar aromatic C–X bonds. , …”

Metal-Catalyzed Cross-Coupling Reactions for Ferrocene Functionalization: Recent Applications in Synthesis, Material Science and Asymmetric Catalysis

“…practical for other iodocyclopentadienyl complexes (Mn, Re). The explanation for these interesting observations was reported recently by Amatore and colleagues [68] (Fig. (15)).…”

Biferrocene Amino Acid, a Ferrocenylogoue of Ferrocene Amino Acid: Synthesis, Cross-Linking, and Redox Chemistry

“…39 One problem associated with Pd-catalyzed coupling reactions is the slow oxidative addition of the ferrocenyl halide to palladium. 40 Therefore, in Stille cross-coupling reactions 41 to give Fc-aryl derivatives an aryl halide and a ferrocenyl stannane are typically employed, 37,42-50 with a notable exception of the reaction of ferrocenyl iodide and tri-n-butyltrifluorovinylstannane. 51 Electron-poor substrates are more suitable for the oxidative addition to Pd.…”