Cation ferrocene

Cationic ferrocene complexes with one, two, and four cationic [B(R)bpy] (bpy = 2,2,-bipyridine) acceptors such as 66 show absorption at Amax = 496-540 nm with the contribution of charge transfer between the ferrocene unit and the B(R)bpy substituent(s) (165). This is confirmed by the EPR spectrum of the monoreduced neutral species, which features a line shape indicating a considerable admixture of the ligand and metal orbitals. Preparation and physical properties of the related polymer, 67, have also been reported (166). 

Asakawa et al. [57] used cyclic voltammetry with a suitable probe to measure the diffusion coefficients of fluorinated surfactant micelles. This method requires a complete solubilization of a small probe into micelles without altering the shape and size of the micelle, a theoretically unattainable condition. A cationic ferrocene derivative, (ferrocenylmethyl)trimethylammonium bromide was introduced into an anionic surfactant (LiPFN, LiFOS, LiHFDeS) micelle by electrostatic interaction. The diffusion coefficient decreased with the addition of salt (LiCl) indicating a salt-induced micelle growth. 

Friedel-Crafts acylation involves electrophilic attack by acyl cation (CHsCO ) on the ring, and the ring s electronic character should indicate its susceptibility to attack. Compare electrostatic potential maps of ferrocene and acetylferrocene. Which molecule contains the most electron-rich ring Which acylation reaction should be faster Does an acetyl substituent enhance or diminish ring reactivity What should be the major product when ferrocene is combined with one equivalent of acetic anhydride ... 

Harrowfield et al. [37-39] have described the structures of several dimethyl sulfoxide adducts of homo bimetallic complexes of rare earth metal cations with p-/e rt-butyl calix[8]arene and i /i-ferrocene derivatives of bridged calix[4]arenes. Ludwing et al. [40] described the solvent extraction behavior of three calixarene-type cyclophanes toward trivalent lanthanides La (Ln = La, Nd, Eu, Er, and Yb). By using p-tert-huty ca-lix[6Jarene hexacarboxylic acid, the lanthanides were extracted from the aqueous phase at pH 2-3.5. The ex-tractability is Nb, Eu > La > Er > Yb. 

As mentioned above, ferrocene is amenable to electrophilic substitution reactions and acts like a typical activated electron-rich aromatic system such as anisole, with the limitation that the electrophile must not be a strong oxidizing agent, which would lead to the formation of ferrocenium cations instead. Formation of the CT-complex intermediate 2 usually occurs by exo-attack of the electrophile (from the direction remote to the Fe center. Fig. 3) [14], but in certain cases can also proceed by precoordination of the electrophile to the Fe center (endo attack) [15]. 

The trans-azo bridge acts as a spacer assisting in the electron exchange between ferrocene moieties, similar to the vinylene bridge, as given for AE° of azoferrocene (25) in Table IV and its IT band feature (92,153). The mixed-valence cation of 25 formed in benzonitrile by le ... 

The ferrocenyldiphynylpropargyl cation, 77, has an intrinsic delocalization nature exhibiting a valence tautomerization band at 856 nm, and its nucleophilic trapping reactions give rise to the formation of ferrocenyldiphyenylallenes (173). The bis(acetylide) mixed-valence complexes of ferrocene and the Ru complex moiety, 78, also behave as a fulvene-cumulene structure, 79, showing a u(M=C = C—C) band at 1985 cm-1 (174). Related alleylidene and cumulenylidene complexes of transition metals have been reviewed by Bruce (175). 

Although the mercuration of ferrocene has been reported for many years, only recently has the mechanism of this reaction been elucidated. Recent studies indicate that the soft mercuric cation undergoes complexation to the Lewis-basic iron center prior to mercuration. This event is followed by the rate-limiting endo-attack of the cyclopentadienyl ring and subsequent product formation (Scheme 7).103... 

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