Relationships between 57Fe NMR, Mössbauer parameters, electrochemical properties and the structures of ferrocenylketimines

Versatility in the mode of coordination {(N), (N,O)−, (C,N)− or (C,N,O)2−} of [(η5-C5H5)Fe{(η5-C5H4)–CHN–(C6H4-2OH)}] to palladium(II)

“…The C@N-bond length {1.28(4) Å } is similar to those found for 1b {average value for the two non-equivalent molecules: 1.26(2) Å [16]} and related ferrocenyl Schiff bases [18,19]. The values of the torsion angles C(10)-C(11)-N-C(12) and C(10A)-C(11A)-N(A)-C(12A) {179.4(3)°} agree with an anti-(E) conformation of the ligand.…”

“…In general electron-withdrawing groups produce a decrease of the DE q value relative to ferrocene (hereafter referred to as FcH), while for electron-donating susbtituents the effect is opposite. The comparison of the data for 1b [16], 2b, 4b and 6b 3 and FcH [34] reveals that the DE q parameter decreases according to the sequence FcH > 1b > 2b > 4b > 6b, which reflects an increase of the electron-pulling nature of the substituent on the ''(g 5 -C 5 H 5 )Fe(g 5 -C 5 H 4 )'' moiety. Additionally the differences detected in the DE q values for 2b and 4b indicate that the binding of the palladium(II) to the imine nitrogen exclusively has a weaker electron-withdrawing effect than in 4b that contains two bidentate (N,O) À units of the iminoalcohol; while in 6b, 3 where the palladium(II) is directly attached to the ferrocenyl moiety, this effect is stronger.…”

“…The reaction of [(g 5 -C 5 H 5 )Fe{(g 5 -C 5 H 4 )-CH@N-(C 6 H 4 -2OH)}] (1b) [16] with an equimolar amount of Na 2 [PdCl 4 ] in methanol at 298 K for 24 h produced a red solid. Its characterization data (see Section 4) agreed with those expected for trans-[Pd{(g 5 -C 5 H 5 )Fe[(g 5 -C 5 H 4 )-CH@N-(C 6 H 4 -2OH)}] 2 Cl 2 ] (2b) ( Table 1, entry I and Scheme 1, step (A)) in which two units of the iminoalcohol are bound to the palladium(II) through the imine nitrogen exclusively.…”

“…Compound 1b was synthesized as reported before [16] and the remaining reagents used in this work were obtained from commercial sources and used as received. The solvents were dried and distilled before use [36].…”

“…In view of these facts and due to the potential utility of heterodimetallic complexes with ferrocenyl units we were prompted to study the reactivity of [(g 5 -C 5 H 5 )Fe{(g 5 -C 5 H 4 )-CH@N-(C 6 H 4 -2OH)}] (1b) [16] towards palladium(II). Since this product can be easily visualized as derived from 1a by replacement of the phenyl group by a ferrocenyl unit, the comparison of the results obtained for 1b with those reported for 1a will enable us to elucidate the importance of the substituents on the imine carbon {a phenyl (in 1a) or a ferrocenyl unit (in 1b)} on the nature and nuclearity of the final product as well as on the versatility of the modes of bindings of 1a and 1b.…”