Iron diimine

In recent studies on hydrogenation catalyzed by soluble iron-diimine complexes, Chirik and coworkers noted that the major deactivation pathway of these complexes occurs via formation of tj6-arene complexes [54]. 

Cyanide-bridged complexes involving iron-diimine-cyanide complexes are discussed in Section 5.4.3.5.8. 

There is a brief but eomprehensively referenced section on iron in a review of homoleptie 2,2-bipyridyl eomplexes " iron-terpy (3 pages) and iron-quaterpy (1/2 page) complexes have also been briefly reviewed." Absorption spectra and photochemistry of apprcmriate iron diimine complexes are ineluded in a text on polypyridyl and porphyrin complexes." A review of the applieation of ehiral 2,2 -bipyridines, 1,10-phenanthrolines, and 2,2 6, 2"-terpyridines in homogeneous eatalysis eontains a little material on iron complexes of such ligands." ... 

Activation volumes for aquation of Schiff base complexes [Fe(C5H4NCH=NHR)3] + (R = Me, Et, Pr , Bu ) in 0.1 M aqueous HCl are between - -11 cm mol and - -14cm mol v and thus within the range established earlier " for (substituted) tris-l,10-phenanthroline-iron(II) complexes. These positive values are consistent with dissociative activation, as are those for dissociation of [Fe(5Brphen)3] + and of [Fe(5N02phen)3] " " in the presence of edta. AF and values for aquation of [Fe(5Brphen)3] have the subject of isochoric analysis. " Medium effects on activation volumes have been reviewed for iron-diimine complexes in binary aqueous solvent mixtures. 

Okamoto and coworkers recently described the iron-catalyzed cyclotrimerization of alkynes utilizing a low-valent iron-diimine complex that was generated in situ upon reduction with zinc dust (Scheme 9.34) [92]. 

I 3 Highly Active Ethene Polymerization Catalysts u/ith Unusual Imine Ligands Tab. 3.7 Ethene polymerization with iron diimine pyridine/MAO 66-69... 

The synthesis of metal-eoordinated 1-azirines and the reaetions of azirines indueed by metals have opened a new area in the ehemistry of this small ring heteroeyele. Many of the reaetions eneountered bear resemblanee to previously diseussed thermally and photo-ehemieally indueed reaetions of 1-azirines. The reaetion of a series of diiron enneaearbonyls in benzene results in eoupling and insertion to give diimine eomplexes and ureadiiron eomplexes as well as pyrroles and ketones (76CC191). A meehanism for the formation of these produets whieh involves initial 1,3-bond eleavage and generation of a nitrene-iron earbonyl eomplex as an intermediate was proposed. 

Iron(II) diimine and related complexes. P. Krumholz, Struct. Bonding (Berlin), 1971, 9, 139-174 (233). 

Oxidation of Coordinated Diimine Ligands in Basic Solutions of Tris( diimine )iron(III),-ruthenium(III), and -osmium(III)... 

Goodwin HA (2004) Spin Crossover in Iron(II) Tris(diimine) and Bis(terimine) Systems. 233 59-90... 

Aminoantipyrine forms with aniline, for instance, a colored diimine derivative under the oxidative influence of iron(III) ions. 

There are very few examples of asymmetric synthesis using optically pure ions as chiral-inducing agents for the control of the configuration at the metal center. Chiral anions for such an apphcation have recently been reviewed by Lacour [19]. For example, the chiral enantiomerically pure Trisphat anion was successfully used for the stereoselective synthesis of tris-diimine-Fe(ll) complex, made configurationally stable because of the presence of a tetradentate bis(l,10-phenanthroline) ligand (Fig. 9) [29]. Excellent diastereoselectivity (>20 1) was demonstrated as a consequence of the preferred homochiral association of the anion and the iron(ll) complex and evidence for a thermodynamic control of the selectivity was obtained. The two diastereoisomers can be efficiently separated by ion-pair chromatography on silica gel plates with excellent yields. 

Krumholz, P. Iron(II) Diimine and Related Complexes. Vol. 9, pp. 139—174. Lehn, J.-M. Design of Organic Complexing Agents. Strategies towards Properties. Vol. 16, pp. 1-69. 

Keywords Diimines Terimines Iron(II) Spin crossover Spin transition... 

Most helicates have linear axes, though a few helicates with circular axes are known - indeed the chiral (D4) molecular squares formed from Zn2+ and 2,5 -bis(2,2 -bipyridin- 6 -yl)pyrazine, 22, may be regarded as circular helicates (450). The formation of circular or linear forms seems to depend on balances between kinetic and thermodynamic control iron(II)-poly-2,2/-diimine systems with their substitutionally-inert metal centers provide useful systems for disentangling thermodynamic and kinetic contributions. The mechanism of formation of circular helicates of this type is believed to entail a kinetically favored triple helicate intermediate (484). Self-assembly of chiral-twisted iron(III)-porphyrin dimers into extended polynuclear species takes place through the intermediacy... 

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