Ferrocenes salts

Other types of bonding include donation by Ligand TT-orbitals, as in the classical Zeiss s salt ion [Pt( 7 -CH2=CH2)Cl3] [12275-00-2] and sandwich compounds such as ferrocene. Another type is the delta (5) bond, as in the Re2Clg ion, which consists of two ReCl squares with the Re—Re bonding and echpsed chlorides. The Re—Re 5 bond makes the system quadmply bonded and holds the chlorides in sterically crowded conditions. Numerous other coordination compounds contain two or more metal atoms having metal—metal bonds (11). 

Reaction of dibenzofuran, ferrocene, and aluminum powder in the presence of aluminum chloride with subsequent hydrolysis and precipitation of the hexa-fluorophosphate salt gives 34 [80JOM(186)265]. When ferrocene and aluminum chloride are in excess, dicationic complexes 35 result. The reaction leading to 36 was also reported [84JOM(260)105]. 

Interaction of iron(II) chloride with the lithium salt of R4B2NJ (R = Me, Et) gives sandwiches 61 (R = Me, Et) (67ZAAC1, 96MI4), resembling in electronic properties those of ferrocene (99ICA(288)17). The n- rf-) complex stems from the further complex-formation of 61 (R = Me, Et) with mercury(II) salts via the unsubstituted nitrogen atom. 

In a recent continuation of the work on dediazoniation of 2-(2 -propenyloxy)ben-zenediazonium salts (10.55, Z = 0, n= 1, R=H) in the presence of ferrocene, Beckwith et al. (1992) found that 3-ferrocenylmethyl-2,3-dihydrobenzofuran (10.65) is formed. The results are consistent with a mechanism involving electron transfer and dediazoniation followed by homolytic attack on the ferrocenium ion. This investigation resolved a long-lasting dispute regarding the heterolytic or homolytic character of the formation of arylferrocenes from arenediazonium ions (for literature since 1955 see Beckwith et al., 1992, references 1-7). 

The synthesis of the unsymmetrical imidazolium salt 11 bearing a planar-chiral ferrocene was described by Bolm starting from (Rp)-[2-(trimethysilyl)-ferrocenyl] methanol 12 which afforded the salt in good yield after reaction with Ar,M-carbonyl diimidazole and methylation (Scheme 9) [18]. 

Due to the pronounced electron donating character of ferrocene, ot-ferrocenyl carbocations 3 possess a remarkable stability and can therefore be isolated as salts [16]. They can also be described by a fulvene-type resonance structure 3 (Fig. 4) in which the Fe center and the ot-center are significantly shifted toward each other as revealed by crystal stmcture analysis, indicating a bonding interaction [17]. 

The dithiophosphonic acid monoesters, RP(OR )(S)SH can be conveniently prepared by cleavage of dimeric, cyclic diphosphetane disulfides, [RP(S)S]2 with alcohols, silanols, or trialkylsilylalcohols180 and then can be converted into metal complexes M[SPR(OR )]2 without isolation.181 The substituted ferrocenyl anion, (N3C6H4CH20)(CpFeC5H4)PS2 has been prepared in two steps from P4Sio, ferrocene and hydroxymethylbenzotriazole (and its salt was used for the preparation of some nickel and rhodium complexes).182 Zwitter-ionic ferrocenylditiophosphonates,... 

The l,l -diferrocenyl-VT electron donor molecule is structurally similar to diferrocenyltetrathiafulvalene but with the TTF moiety replaced by bis(vinylene-dithio)tetrathiafulvalene (VT) [76]. It has currently not been possible to separate the cis- and trans-isomers. The 1 1 polyiodide complex of l,l -diferrocenyl-VT was obtained through reaction with iodine. EPR and Mossbauer spectra indicate that in this charge transfer salt the VT moiety is oxidized while the ferrocene... 

Fig. 4. The effect of added electrolyte (Bu4N+ salts) on the reduction of approximately 20mM [Co(dmg)3(BF)2]BF4 by ferrocene at —20°C in CH2C12. The solid lines represent the parameters fit to all of the data, as described in the text. From top to bottom Br-, Cl-, BF, N03. In all cases, the rate constant in the absence of ion pairing, from the fitting, is 2.8 xlO5 M-1s-1. Reproduced from Ref. (5) by permission of Elsevier Science.

Carbocations as electron acceptors in aromatic EDA complexes 192 Bis(arene)iron(II) complexes with arene and ferrocene donors 198 Carbonylmetallate anions as electron donors in charge-transfer salts 204 Aromatic EDA complexes with osmium tetroxide 219... 

Solutions were 2 x 10-3 mol dm-3 in compound, and potentials were determined with reference to the SCE, b Three-electron reversible oxidation process. Two-electron reversible oxidation process. Separation between anodic and cathodic peak potentials values for ferrocene under identical conditions ranged from 80 to 90 mV. Shift in respective ferrocenyl oxidation potential produced by presence of guest cation (2 equiv) added as their thiocyanate salts for potassium and ammonium, and their picrate salts for methylammonium and phenethyl-ammonium. 

Obtained in MeCN solution containing 0.1 mol dm 3 Bu°NBF4 as supporting electrolyte. Solutions were 1 x 10 3 mol dm 3 in compound and potentials were determined with reference to an Ag/Ag+ electrode at 21 1°C, 50 mV s scan rate. > p, and represent the anodic and cathodic peak potentials. Cathodic shifts in the metallocene redox couples produced by the presence of anion (5 equiv) added as their tetrabutylammonium salts. As the concentration of the anion increased, the cathodic current peak potential of the ferrocene/ferTOcenium redox couple began to exhibit the features of an EC mechanism. 

This problem will be considered on the basis of charge-transfer coordination of organic polynitriles to substituted ferrocenes. The practical significance of the charge-transfer coordinative species (salts) is their ferromagnetic behavior (see Section 8.5). The salts contain the cation-radical and anion-radical counterparts. Peculiarities in electronic structures of the cation-radical parts within the salts are topics of our interest. 

In contrast, ferrocene, l,T-dimethylferrocene, decamethylferrocene, and 1,2-diferrocenylethane all react with DDQ forming a dark green 1 1 ion-radical salt. Both (DDQ) and ferrocenium constituents of the salts were characterized by their typical electron spectra (Salman et al. 2004). Sometimes, even a weak charge transfer can transform the ferrocenyl substituent into the full-value hole reservoir acting intramolecularly. Scheme 1.31 gives two such examples. One of them describes the effect of charge-transfer coordination between Sc + as an acceptor and a ferrocene derivative as a donor (Qkamoto et al. 2003). The other example introduces the effect of charge-transfer coordination between pyridine as a donor and a ferrocenium derivative as an acceptor (Hillard et al. 2006). 

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