Electron transfer series

The electron transfer series W(R2fi ic)4° W(R2tfic)4 -> W(R2rfic)4 was detected by voltametric measurements (37), the half wave potentials are 0.24 and 0.36 V lower than the corresponding values of the molybdenum compounds. Both transfers obey the Taft relation with a low value of p, which points to a rather small contribution of the ligand orbitals into the redox orbitals. 

The Mn-S distances vary from 2.32 (1) to 2.35 (1) A, whereas in Mn(Et2rftc)3 the manganese atom is surrounded by three opposing pairs of sulfur atoms at distances of 2.38 (1), 2.43 (1) and 2.55 (1) A (47). Electrochemical studies (43) in acetone and dichloromethane showed one-electron transfer series ... 

The most characteristic feature of nickel dithiolene complexes is the existence of an electron transfer series whose members are interrelated by reversible one-electron steps. Three members I-III of the series, I and III being diamagnetic and II having an S= 1/2 ground state, are preparatively accessible [Ni(S2C2R2)2]2 (I) <- [Ni(S2C2R2)2]1 - (II) <- [Ni(S2C2R2)2] (HI). 

MS6C6R.6], much interest has been generated in these complexes, particularly with respect to attempts to elucidate their electronic structures.4,5 The most noteworthy feature of the chemistry of these complexes is that many with the same M and R may be interrelated by relatively facile one-electron-transfer reactions which may be effected chemically or electrochemically. Complexes with varying over-all charges z may then be formed which constitute members of electron-transfer series.5,8,9,16 Such series with two or three members have been obtained. Tables I and II list representative complexes or series of complexes which either have been isolated or whose existence has been demonstrated by electrochemical measurements. 

Fe—2S] clusters cysteines, 38 294 P-band spectrum, 38 191-192 X-band spectrum, 38 189 [2Fe—2S] clusters EPR spectroscopy, 38 187 excess electron localization, 38 179-180 [3Fe-4S] clusters, 38 16-24, 119-120 conversion reactions, 38 17-18 D. africanus Fd III, 38 138-144 electronic structure, 38 19 electron transfer series, 38 18-19 formation, oxidation and spin states, 38 17-22... 

The electron transfer series of [Fe(NO)(cyclam-ac)F (x = +2, +1, and 0) (102) (Fig. 14) that composes the FeNO " (re = 6, 7, and 8) complex series in the convenient notation suggested by Enemark and Feltham (103) is a good example that clearly shows the value of DFT calculations applied together with experimental Moss-bauer and IR spectroscopy to gain insight into the electronic structure of metal—radical complexes. 

SINGLE ELECTRON-TRANSFER REACTIONS, ELECTRON-TRANSFER SERIES AND LINKED 493 REDOX CENTRES... 

Several classes of coordination compound undergo several successive, reversible one-electron-transfer reactions. These comprise a so-called electron-transfer chain or series .8 Cyclic voltammetry is particularly useful for recognizing such behaviour and an example is illustrated by Figure 2. This shows the four members of the electron-transfer chain [Fe4S4(SPh)4]"-, n = 1-4.5 An electron-transfer series provides the coordination chemist with a means of examining the consequence of systematic addition (or removal) of electrons from a nominally fixed geometry thermodynamic, kinetic and spectroscopic relationships between members of a series can be explored.9... 

Figure 2 Electron-transfer series [Fe4S4(SPh)4]4-/3-/2-h- (3.8 mmol dm-3) in 3 1 to)uene [NBu4][BF4] at 23 °C, using platinum electrode and scan rate of 0.1 V s-1...

McCleverty and Ratcliff148 investigated the redox chemistry of the complexes and found a three-or even four-step electron transfer series to exist in these compounds as well. 

The fourth volume of the PET (Photoinduced Electron Transfer) series is again devoted to some fundamental topics. All the chapters present comprehensive reviews. I am very grateful to the authors whose efforts have made this venture possible, especially, since two of them have already contributed to previous issues. 

Figure 28. Noninnocence of the dithiolene ligand in the [M(dithiolene)2]01 2 electron-transfer series. [Adapted from (328).]...

The Holm and co-workers (328) study provided a very nice correlation between the electronic and geometric structures of the entire. i(S2C2Me2)2, u 2 electron-transfer series (Fig. 31), providing key electronic structure contributions to the redox behavior of these molecules. The Ni—S bond... 

The complex is readily soluble in strongly polar solvents giving a green-brown or green solution. Yoltammetric examination2 of dichloromethane solutions containing this anion reveals that it is a member of the electron-transfer series ... 

These results show that clusters 4 and 5 are related by one electron as the first two members of an at least four-membered electron transfer series ... 

Table 8 The electron-transfer series of [FedSd] protein sites and analogs showing core oxidation states and iron valences...

Figure 2 Electron transfer series in native and synthetic model clusters of the Fe4S4 center in the Fe-protein. Redox potential versus NHE, Fe Mossbauer isomer shift (S at 4.2 K vs. iron), mean iron oxidation state, and spin state are indicated for each redox state. Syntheses and ligand-substitution reactions are indicated for synthetic clusters...

The tetracobalt cubanes [ Co(/Li3-S)Cp 4] (67) (M = Co, E = S) have not been studied as extensively as the iron analogues (Section IV,B), but it is to be expected that electrochemical studies will reveal an extensive electron-transfer series. A comparison of the structures of [ Co(/i3-S)Cp 4] (2 = 0 and 1) showed that the nonbonded tetrahedron of metal atoms in the neutral molecule (Co—Coave = 329.5 pm) undergoes a tetragonal distortion. The shortening of four of the cobalt-cobalt distances (317.2 pm) is due to the removal of an electron from an orbital antibonding with respect to the four metal atoms 190). 

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