Iron complexes pyridyl

Iron complexes with the pentadentate ligand 3 derived from pyridyl and prolinol building blocks containing a stereogenic center were reported from the group of Klein Gebbink (Scheme 4) [34]. In alkene oxidations with hydrogen peroxide,... 

The first report of catalyzed chain growth on aluminum was presented by Samsel et al., using metallocenes of actinides [13] or hafnium [14, 15], Gibson et al. described a detailed study of chain growth using the bis(imino)pyridyl iron complex 1 in combination with several metal alkyls [16], Other systems reported to... 

Further variations on the theme have been achieved54 by anchoring species such as [RuivO-(terpy)(py)]2+ or complexes of osmium.55 Iron complexes have also been studied for example, evaporation of a solution containing [Fe(CN)5(H20)]3 and PVP on to an electrode will immobilize the pentacyanoferrate as a pyridyl complex, one in three available pyridyl groups being used to avoid precipitation prior to evaporation of solvent. 

The A(A(Af ,A ,-tetrakis(2-pyridyl-methyl)-2-hydroxy-l,3-diamino-propane was prepared by crushing para-chloropicoline (0.097 mol) and mixing it with 2-hydroxy-1,3-diamino-propane (0.016 mmol) [5-6]. The mixture is heated to 170-180°C for 1 hour, till gas formation stops. After cooling the red glassy structure is diluted with HCl (150 ml, 4M), thus a blue precipitate arises. After filtration the precipitate is washed several times with acetone. The precipitate is then dissolved in water and neutralised with a diluted ammonia solution. The white precipitate is recrystallised in acetone and crushed to a fine powder and then dried under vacumn. To an ethanolic solution with Fe(N03)3.6H20 (0.31 g) the HPTP (0.3 g) is added. The precipitate of binuclear iron complex is collected. 

S.-F. Li, H.A. Mottola, Continuous flow determination of relative diffusion coefficients of iron complexes with ligands of the 1,10-phenanthroline family and with 3-(2-pyridyl)-5,6-diphenyl-l,2,4-triazine in acetonitrile-water solutions, Anal. Chim. Acta 289 (1994) 79. 

Fig. 1 Structure of bis (iminoaryl)pyridyl iron complexes BI P FeCl2, where R refers to the ortho substituents on the imino aryl part...

Although the iron 77 -alkene interaction is the key to many of these catalytic reactions, discrete organometallic complexes have not been isolated in most cases. Thus, for example, the activation of the complexes (2,6-bis(aryl-imino)pyridyl)iron dichloride with MAO (methylaluminoxane) yields an ethylene oligomerization catalyst which is likely to involve an intermediate t7 -C2H4 iron species such as 17 (Scheme 17). The iron catalysts of this type yield a-olefms with a Schulz-Flory distribution as well as linear homopolymers. This is the first time that the simultaneous production of both products has been reported.Iron-alkene intermediates are also important in addition reactions. Thus, the reactions of some aminocarbene iron complexes with electron-deficient alkenes lead to 1,4-dicarbonyl compounds via iron-alkene intermediates as shown in Scheme 18. 

A new family of 2,6-bis(imino)pyridyl iron complexes has been prepared and used as catalyst precursors for ethylene oligomerization to give linear a-olefins, via r/ -alkene intermediates. The use of Fe(CO)s as a catalyst precursor in the hydrogenation of cyclohexene and 1-hexene is believed to go via the intermediates Fe(GO)4(alkene) and HFe(CO)3( -allyl) 18. ... 

Hartl and Reek ° reported the development of iron complexes 65a and 65b, bearing pyridyl and phenyl groups, respectively, at 3,3 -positions of the BINOL moiety. The syntheses of these metal complexes involved the substitution of one carbonyl ligand in [Fe2(p-pdt)(CO)6] by a phos-phoramidite ligand (pdt=S(CH2)sS). The structure was corroborated by P NMR, IR and MS spectra, revealing single CO displacement and phosphoramidite coordination to the Fe centre via the phosphorus atom. 

Compounds 139 are tris(oximehydrazone) derivatives with an iron(ll) ion in the center of the cavity [230]. Compound 140 (Fig. 38) has been known for 30 years [231, 232] and was prepared from a tris(2-aldoximo-6-pyridyl)phos-phine that is capped by a BF unit to encapsulate cobalt(ll), zinc(ll), nickel(ll), and iron(II). All four macrocyclic complexes were characterized later by a comparative X-ray crystallographic study [233-236]. 

The reduction of persulphate by tris-[a-(2-pyridyl)-benzylideneaniline] iron(II) is, by contrast, independent of persulphate ion concentration , and the rates of reaction of several ring-substituted complexes of this type correspond exactly to the rates of acid-catalysed separation of one ligand. Clearly oxidation of the ligand... 

There have been no reports of complexes of " JV-substituted thiosemicarbazones derived from 2-formylpyridine, but 2-acetylpyridine JV-methyl-thiosemicarbazone, 3a, formed [Fe(3a-H)2]C104 and [Fe(3a-H)2]FeCl4 [117]. The nature of these two species was established by partial elemental analyses, molar conductivities, magnetic moments, electronic, infrared, mass and electron spin resonance spectra. A crystal structure of a related selenosemicarbazone complex confirmed the presence of a distorted octahedral iron(III) cation coordinated by two deprotonated anions so that each ligand is essentially planar and the azomethine nitrogens are trans to each other the pyridyl nitrogen and selenium donors are both cis. 

The S-methyldithiocarbazates of both 2-picolylphenylketone, 16, and 2,6-luti-dylphenylketone, 17, yielded high spin iron(Ill) complexes, [Fe(15-H)Cl2(H20)] and [Fe(16-H)Cl2(H20)] [144]. Both complexes involve a tridentate ligand bonding via the pyridyl nitrogen, azomethine nitrogen and thiol sulfur. 

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