Donor ferrocene

Compounds 42 and 43 are based on the PBI acceptor, made soluble by a C19 swallowtail attached to one imide nitrogen The donor is attached through the other imide nitrogen. In 42, the moderate donor pyrene is separated from the PBI by a Ci ct bridge that holds the donor and acceptor close to perpendicular, with limited motion possible. Nonetheless, 42 has a persistent, small RR (Fig. 18g) [106]. In 43, the good donor ferrocene is separated from the PBI by a more flexible C2 a bridge. It has an IVT band that peaks at 595 nm and forms a rectifier with a persistent RR between 25 and 35 (Fig. 18h) [106]. 

A longer CS lifetime was also attained by attaching an electron donor (ferrocene, Fc) to a ZnP—Cgo dyad to give a triad (Fc—ZnP—Cgo) (43). Upon photoexcitation of the ZnP moiety, ET from ZnP to Ceo occurs within 230 ps, followed by hole transfer to Ec after 500 ps to produce the long-lived CS state (Scheme 4). The CS lifetime (630 ps) of Ec + —ZnP—Cgo is much longer than the lifetime (8 ps) of a similar triad linked by longer amide linkage (34). 

Hetnarski [110] in a number of papers has described a new donor - ferrocene. It gives EDA complexes with sym-trinitrobenzene, picric acid, picryl chloride while using Job method [109] to establish the ratio between the acceptor and donor. 

Ferrocene and a number of other non-electron donor ferrocenes have been intercalated into M0S2 by treating a saturated CCI4 solution of the guest with a suspension of exfoliated M0S2. The interlayer spacings for the substituted... 

Guldi D M, Maggini M, Scorrano G and Prato M 1997 Intramolecular electron transfer in fullerene/ferrocene based donor-bridge-acceptor dyads J. Am. Chem. See. 119 974-80... 

Phospholes and analogs offer a wide variety of coordination modes and reactivity patterns, from the ti E) (E = P, As, Sb, Bi) through ri -dienic to ri -donor function, including numerous and different mixed coordination modes. Electrophilic substitution at the carbon atoms and nucleophilic properties of the phosphorus atom are well documented. In the ri -coordinated species, group V heteroles nearly acquire planarity and features of the ir-delocalized moieties (heterocymantrenes and -ferrocenes). 

In many respects, the successes of this model are remarkable. Iron(O) possesses a total of eight electrons in its valence shell. To satisfy the eighteen-electron rule, five two-electron donors are needed, and compounds such as [Fe(CO)5] are formed. These molecules also obey simple VSEPR precepts, and [Fe(CO)s] adopts a trigonal bipyramidal geometry. Conversely, the use of two five-electron donor ligands such as the strong r-acceptor cyclopentadienyl, Cp, gives the well-known compound ferrocene (9.3). 

Palladacycles are defined as compounds with a Pd-C CT-bond with the Pd being stabilized by one or two neutral donor atoms, typically forming 5- or 6-membered rings [51]. Ferrocenyl palladacycles constitute a particularly attractive catalyst class partly due to the element of planar chirality. The first diastereoselective cyclopallada-tion of a chiral ferrocene derivative was reported in 1979 by Sokolov [52, 53]. 

Ferrocen-l,l -diylbismetallacycles are conceptually attractive for the development of bimetal-catalyzed processes for one particular reason the distance between the reactive centers in a coordinated electrophile and a coordinated nucleophile is self-adjustable for specific tasks, because the activation energy for Cp ligand rotation is very low. In 2008, Peters and Jautze reported the application of the bis-palladacycle complex 56a to the enantioselective conjugate addition of a-cyanoacetates to enones (Fig. 31) [74—76] based on the idea that a soft bimetallic complex capable of simultaneously activating both Michael donor and acceptor would not only lead to superior catalytic activity, but also to an enhanced level of stereocontrol due to a highly organized transition state [77]. An a-cyanoacetate should be activated by enolization promoted by coordination of the nitrile moiety to one Pd(II)-center, while the enone should be activated as an electrophile by coordination of the olefinic double bond to the carbophilic Lewis acid [78],... 

The [Fe-Cp]-fragment does not only play the role of an additional steric element introducing planar chirality into the otherwise flat pyridine system. Substitution at the pyridine 2-position usually cuts the nucleophilicity of the nitrogen atom thus limiting the possibilities to achieve efficient chirality transfer using nucleophilic pyridine catalysts [84]. Ferrocene, however, functions as a strong electron donor (see Sect. 1) and thus restores the nucleophilicity impaired by substitution. 

Coordination of pentafluorophenyl gold(III) to the two free N-donor atoms in 1,1 -bis(2-pyridylthio)ferrocene leads to the dinuclear complex [ Au(C6F5)3 2 Fc(Spy)2 ] structurally characterized [149]. 

Azo-bridged ferrocene oligomers also show a marked dependence on the redox potentials and IT-band characteristics of the solvent, as is usual for class II mixed valence complexes 21,22). As for the conjugated ferrocene dimers, 2 and 241 the effects of solvents on the electron-exchange rates were analyzed on the basis of the Marcus-Hush theory, in which the t/max of the IT band depends on (l/Dop — 1 /Ds), where Dop and Ds are the solvent s optical and static dielectric constants, respectively (155-157). However, a detailed analysis of the solvent effect on z/max of the IT band of the azo-bridged ferrocene oligomers, 252,64+, and 642+, indicates that the i/max shift is dependent not only on the parameters in the Marcus-Hush theory but also on the nature of the solvent as donor or acceptor (92). 

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... 

Shumate WJ, Mattem DL, Jaiswal A, Burgess J, Dixon DA, White TR, Honciuc A, Metzger RM (2006) Spectroscopic and rectification studies of three donor-sigma-acceptor compounds, consisting of a one-electron donor (pyrene or ferrocene), a one-electron acceptor (perylenebisimide), and a C19 swallowtail. J Phys Chem B110 11146-11159... 

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