Iron amido complexes

Ligand deprotonation may result in some interesting ambiguities in oxidation state, which ultimately allow us to consider new patterns of reactivity. We begin by considering the iron(m) complex of a macrocyclic amine 5.18. Deprotonation of the amino group in the complex gives an iron(m)-amido complex 5.19 (Fig. 5-34). 

Figure 5-34. The deprotonation of an iron(m) complex of a macrocyclic amine to give an iron(m)-amido complex. The presence of the lone pair of electrons (negative charge) on the deprotonated nitrogen atom is emphasised ( ).

Figure 5-35. Tautomeric forms of the iron(in)-amido complex generated in Figure 5-34. The iron(n) complex 5.20 is simply a tautomeric form of 5.19, in which an electron has been transferred from nitrogen to the iron(m) centre.

However, the iron(m)-amido complex could also be written as an iron(n) amido radical complex 5.20. These two representations are, of course, simply limiting valence bond descriptions of the complex (Fig. 5-35). The difference simply involves the transfer of one electron from the lone pair on the nitrogen in 5.19 to the iron(ni) centre. 

Chatancin, via ring-closing metathesis, 11, 252 Chelate coordination, monoenes, in Pd(II) complexes, 8, 331 Chelated alkenes, with iron, 6, 133 Chelated allyl complexes, with iron, 6, 140 Chelating aryloxides, with Zr(IV), 4, 784 Chelating bis(amido) complexes, with Zr(IV), 4, 767 Chelating bis(amido) phosphine-donor complexes, with Zr(IV), 4, 816... 

This compound is a precursor to a wide variety of three- and four-coordinate iron(II) complexes, including alkyl, aryl, hydride, sulfido, amido, and fluoride... 

A detailed mechanistic study of the chemical and electrochemical oxidative dehydrogenation of the iron(II) complex 14 has been reported. The key intermediate is an iron(II) amido complex which is tautomeric with an iron(II) amido radical species it is this species which undergoes electron loss to give the iron(II) complex of a C-protonated imine (Scheme 6). The reaction of dicyclohexylcar-bodiimide, RN=C=NR, with ReClg results in nucleophilic attack of halide upon the diimide to yield complexes of RNHCC1=NR. The complex... 

Tris(amido)phosphines 40-43 react with Fc2(CO)9 to give mononuclear iron carbonyl complexes Fe(CO)4(PR3). IR data collected from these complexes, combined with data from similar complexes, revealed the TT-acidity of the phosphines to be 41 w 40 > 43 > P(OPh>3 >42 > PPh3 > P(NMe2)3- Variable-temperature NMR on the Fe(GO)4 complexes of 41-43 showed rapid exchange of axial and equatorial carbonyls from —80 to 20 °C, while complex 40 showed slow axial-equatorial carbonyl exchange even at room temperature, attributed to the steric bulk and rigidity of the ligand. 

A series of 4-alkylamido-2-hydroxybenzoic acids containing a different number of carbon atoms in the alkyl-amido group has been studied as model ligands for metal ion extraction in aqueous micellar solutions of nonionic surfactants. Their acid-base properties and reactivity towards metal ions in the presence of micelles were investigated. By operating at a proper temperature, the separation of the iron (III) chelate complexes into a micellar rich phase was achieved and the extraction efficiency was correlated with the ligand hydrophobicity. 

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