Effects of the nature of the nitrogen donor atom (sp2versus sp3) upon the properties and chemistry of palladated complexes with σ(Pd–Csp2, ferrocene) bonds

Abstract

The NMR and Mössbauer spectra and electrochemistry of the N-donor ferrocenyl ligands [Fe(η⁵-C₅H₅){(η⁵-C₅H₄CHNCH₂Ph)}] and [Fe(η⁵-C₅H₅)(η⁵-C₅H₄CH₂NMe₂)] as well as their mononuclear derivatives with σ(Pd–C_sp², ferrocene) bonds [[graphic omitted]CH₂Ph)}Cl(L)], [[graphic omitted]Me₂)}Cl(L)][L = 1 -methylimidazole (mim) or PPh₃], and [Pd{(η⁵-C₅H₅)Fe(η⁵-C₅H₃CH₂NMe₂)}Cl(PPh₃)₂] have been studied. Comparison of the data allows an understanding of the influence of the nature of the N-donor atom of the ferrocenyl moiety (sp²versus sp³) upon the properties of these compounds. In particular, the differences observed in the quadrupole splitting parameters obtained from Mössbauer spectroscopy reveal not only that the palladium(II) acts as an electron-withdrawing group in all these cyclometallated derivatives, but also that most of the electron density is withdrawn from the imine CHN moiety in the derivatives containing ferrocenyl Schiff bases as ligands. The crystal structures of [[graphic omitted]CH₂Ph)}Cl(PPh₃)] and [[graphic omitted]Me₂)}Cl(mim)] have been determined.