INFLUENCES OF THE ELECTRONIC AND STERIC EFFECTS OF THE SUBSTITUENTS IN CYCLOPALLADATION OF FERROCENYLHYDRAZONES

The syntheses and characterization of seven novel ferrocenylhydrazones of general formulae: [(eta(5)-C5H5)Fe((eta(5)-C5H4)-CH=N-NH(R)}] {wit h R=C6H4-4-Cl (1a), C6H4-4-NO, (Ib), C6H5 (1c), C6H3-2,4-(NO2)(2) (1d) , C6H3-2,5-(Cl)(2) (le), C6F5 (If) or C6H4-2-CH3 (Ig)} are reported. W e also describe the reactions of compounds 1 with PdCl2 in refluxing e thanol, by which different cyclopalladated complexes containing sigma( C-sp2,(aryl)-Pd), sigma(C-sp2, (ferrocene)-Pd) or sigma(C-sp3-Pd) bond s were obtained. A comparative study of the ease by which a sigma(C-sp 2 ferrocene-H) or a sigma(C-sp2,C- aryl-H) bond in compounds 1 and in the ferrocenylhydrazones: [(eta(5)-C5H5)Fe{(eta(5)-C5H4)-C(CH3)=N-NH(R )}] (1') {derived from acetylferrocene) were to be activated is also r eported. (C) 1998 Elsevier Science S.A. All rights reserved.