Diiron bridging complexes

In a second approach to preparing clusters with multiple diiron centres. Song et al. have utilized the diiron-bridged complexes 145, prepared from the reactions of Fe3(GO)i2 with the appropriate dithiol in the presence of Et3N, as a building block to synthesize a range of chains and macrocycles containing up to four diiron centers. 

Scheme 23 Formation of the catalytic active )i-oxo-bridged diiron(IV) complex...

Fig. 9. Composition (5a, X12 = H 5d, X12 = OCH3) and ORTEP (5a) structures of the black p-oxo-bridged diiron(IV) complex rapidly formed in a high yield from la,d and 02 in CH2C12 or other weakly coordinating solvents. The ellipsoids are drawn at the 50% probability level. From Ref. (38).

The mechanism for the formation of singly germylene-bridged complexes is considered to be identical with that for the formation of analogous silylene-bridged complexes shown in Scheme 3. On the other hand, the doubly germylene-bridged diiron complexes in Eqs. (42) and (43) are likely to form via the intermediate formation of K-type complexes. 

Tolman, W. B., Liu, S., Bentsen, J. G., and Lippard, S. J., 1991, Models of the reduced forms of polyiron-oxo proteins An asymmetric, triply carboxylate bridged diiron(ll) complex and its reactions with dioxygen, J. Am. Chem. Soc. 113 1529164. 

Deprotonated bridging dithiolate ligands in diiron carbonyl complexes of type 101 (R = H, Ph) rearrange intramolecularly by nucleophilic attack on an iron atom while an electron pair is displaced onto a sulfur atom with formation of an Fe—C bond in 102 (76). Neutral derivatives can be formed upon further alkylation, leading to type Ij complexes (Table 1). The bridg-... 

The chemistry of the highly electrophilic cationic diiron bridging methylidyne complex [ Fe(CO)Cp 2(/x-CH)(/x-CO)] (75) has been probed extensively with an emphasis on C-C bond forming capabilities. For instance, alkenes react to give one of two possible products (i) alkyli-... 

S. Taktak, S. V. Kryatov, T. E. Haas, E. V. Rybak-Akimova, Diiron(lll) oxo-bridged complexes with bpmen and additional monodentate or bidentate ligands Synthesis and reactivity in olefin epoxidation with H2O2, / Mol. Catal. A Chem. 259 (2006) 24. 

Mixed-valent FenFenl intermediates were observed in several cases during the oxygenation of diiron(II) complexes, most probably due to a one-electron outer-sphere oxidation. Oxo- or hydroxo-bridged diiron(III) complexes were the final products of these oxygenation reactions. The overall mechanism of these transformations is apparently complex and not well understood yet.77... 

FIGURE 4.22 Dinucleating aminopyridine ligands supporting alkoxy-bridged diiron-oxygen complexes. 

FIGURE 4.23 Oxygenation of alkoxo-, carboxylato-bridged diiron(II) complexes with dinucleating aminopyridine ligands.17... 

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