Syntheses, crystal structures and electrochemical studies of bi- and trimetallic conjugated ferrocene-based complexes

Donor/acceptor organotriiron(II) hydrazone chromophores: structural, spectroscopic and electrochemical properties

“…The through-bond and through-space FeÁ Á ÁFe distances are of 9.662 and 7.491 Å , respectively. As already seen in the crystal structures of the starting bis-ferrocene-based aldehyde 3 and of its trimetallic derivatives (E,E)-Fc-Fc-CH@CH-C 5 H 4 N-M(CO) 5 (M = Cr, Mo, W) [9], the bis-ferrocene fragment in 4 + adopts also the anti-conformation with a dihedral angle of 8.50°between the two C 5 -ring planes of the dinucleating (E)-[C 5 H 4 -CH@CH-C 5 H 4 ] 2À ligand. The through-bond and through-space Fe(2)Á Á ÁFe(3) distances are 8.347 and 7.195 Å , respectively.…”

“…The through-bond and through-space Fe(2)Á Á ÁFe(3) distances are 8.347 and 7.195 Å , respectively. As for the 1,1 0 -bis-substituted ferrocenyl complexes reported so far in the literature [9,17], 4 + adopts the sterically more hindered conformation with a parallel disposition of the ancillary ligands (see Fig. 1), in which intramolecular p-stacking could have some effect.…”

“…1), in which intramolecular p-stacking could have some effect. However, in the cases of 4 + , of the organometallic aldehyde (E)-Fc-Fc-CHO 3 [9], and of the bimetallic ferrocenyl 1,1 0 -bis-substituted hydrazone complex ðEÞ-½CpFeðg 6 -p-MeC 6 H 4 ÞNHN@CHðg 5 -C 5 H 4 Þ Feðg 5 -C 5 H 4 Þ-CH@CH-C 6 H 4 -p-Me þ PF À 6 [7a], where p-stacking is not possible, the same hindered conformation is also observed. This indicates that packing effects may be having a more important influence in the steric disposition of the molecule in the crystal.…”

“…These assignments were made by analogy to the oxidation potentials of their respective bimetallic counterparts 6 þ PF À 6 and 7 þ PF À 6 , and their relative position with respect to the ferrocene/ferrocenium couple. Like for the starting aldehyde material 3 [9], the half wave potential of the ferrocenyl moieties show a clear anodic shift (120-130 mV) compared to the parent complex Fc-CH@ (10) 2.82 159 a Symmetry transformations used to generate equivalent atoms: (a) 1 + x, y, z; (b) 3/2 À x, À1/2 + y, z. b Potentials are taken as the midpoints between anodic and cathodic peaks.…”

“…The new trinuclear hydrazone chromophores ðEÞ-½Fc-Fc-CH@N-NH-ðg 6 -p-RC 6 H 4 ÞFeCp þ PF À 6 ðR ¼ Me; 4 þ PF À 6 ; MeO; 5 þ PF À 6 Þ were successfully prepared by a condensation reaction of the ionic organometallic hydrazine precursors ½CpFeðg 6 -p-RC 6 H 4 NH-NH 2 Þ þ PF À 6 ðR ¼ Me; 1 þ PF À 6 ; MeO; 2 þ PF À 6 Þ with the bis-ferrocene-based aldehyde building block (E)-FcFc-CHO (3) [9], in refluxing ethanol solution containing catalytic amounts of concentrated acetic acid (Scheme 1). The two complexes were isolated as spectroscopically pure, air and thermally stable orange microcrystalline solids, in reasonable yields of 38% and 35%, respectively, after recrystallization from CH 2 Cl 2 diethylether mixture.…”