Charge Transfer Properties of Multi(ferrocenyl)trindenes

Abstract

Ferrocenyl, diferrocenyl, and triferrocenyl complexes of dihydro-1H-trindene have been prepared by up to 3-fold bromide substitution of the dihydro-2,5,8-tribromo-1H-trindene halocarbon. The charge transfer properties of their mono-, di-, and tricationic derivatives were investigated. The cations of this new family of multi(ferrocenyl)trindene complexes were generated by chemical oxidation using (acetylferrocenium)(BF4) as the oxidative agent and monitored in the visible, IR and near-IR regions. The charge transfer bands in the near-IR spectra are rationalized in the framework of the Marcus–Hush theory. In particular, the triferrocenyl complexes display a redox chemistry that can be switched from a unresolved three-electron oxidation to two consecutive one-electron and two near simultaneously occurring one-electron oxidations by changing the supporting electrolyte from [nBu4N][PF6] to [nBu4][B(C6F5)4]. In addition, the introduction of the third ferrocenyl group increases the strength of the metal–metal interaction with respect to that of the structurally related diferrocenyl system

The core of the matter – arene substitution determines the coordination and catalytic behaviour of tris(1-phosphanyl-1′-ferrocenylene)arene gold(i) complexes

“…36 As the groups of Lang and Santi have extensively shown, the nature of the arene core is decisive for the electrochemical response of the system both in terms of redox potentials and electronic communication, that is, the existence of mixedvalent oxidised states. [21][22][23][37][38][39][40][41][42][43][44][45][46][47][48][49] In our case, 1 : 1 ligand-tometal complexes of triazine derivative 1a (Chart 2, left) showed a distinct delocalised coinage metal-π(C 3 N 3 ) interaction, 50 while 1 : 3 ligand-to-gold complexes of 1a-c (Chart 2, right) demonstrated how the electron density of the respective core determined the electrochemical response both with respect to redox potential and reversibility. Furthermore, the arene cores were also found to impact the catalytic activity of these trinuclear gold(I) complexes in the ring-closing isomerisation of N-(2-propyn-1-yl)benzamide (2) to 5-methylene-2-phenyl-4,5dihydrooxazole (3a).…”

“…Notable examples include the BIFEP (II) and TRAP (III) ligand families, 16,17 mesoionic carbene IV, 18 terferrocene-based bis(terpyridine) V, 19 and C 2 -symmetric tetradentate TriFer VI. 20 Furthermore, a number of discrete multiferrocenyl compounds [21][22][23][24][25][26][27] and ferrocenyl-containing dendrimers have been reported over the last years. [28][29][30][31] Conceived as small-molecule analogues of redox-switchable dendrimers, [32][33][34] we have recently reported the synthesis of a new family of tris-phosphanes 1 (Chart 1) incorporating a redox-active, C 3 -symmetric tris(ferrocenyl)arene backbone.…”

Multiferrocenyl Cobalt‐Based Sandwich Compounds

“…[52,68,69] However, a high degree of electronic coupling was observed for species with a low redox splitting. [41,[70][71][72][73][74] Furthermore, there are class I compounds according to the classification of Robin and Day [75] known, that show high ΔE°′ values. [5,27,76,77] The cyclic voltammogram of 5c shows six partially overlapping, electrochemically reversible redox events (Figure 7).…”

Charge Transfer Properties of Benzo[b]thiophene Ferrocenyl Complexes

“…In the case of 51, the charge of pentamethylated ferrocenyl is partially shielded causing the decrease of the electrostatic interaction with the two other oxidized ferrocenyl that arrange at opposite sides in order to minimize their mutual repulsion. We have recently described the synthesis, electrochemistry of a family of mono-(52), bis-(53) and tris(ferrocenyl) (54) complexes of dihydro-1H-trindene (TdH), 65 a polycyclic hydrocarbon synthesized by Katz and Ślusarek in the early 1980s. 66 The use of TdH as a metal bridging ligand is particularly favourable because strain is minimal as a consequence of the presence of only five-and six-membered rings.…”