Iron complexes, with ethylene

Attachment of dendritic wedges of either the carbosilane or benzylphenyl ether type to the para-hydroxy aryl site in [2,6-(ArN=CMe)2C5H3N (1 R = Me, Ar = 2-Me-4-OHC6H3), has been shown to proceed in good yield [162], Complexation with iron(II) chloride allows access to dendrimer-supported precatalyst 42 (Scheme 13). Using MAO as a co-catalyst, it was shown that 42 are active in the oligomerisation of ethylene the activity of these new catalysts is not, however, related to the type of dendritic wedge employed. 

In contrast, the related diamines 45 and 46 [cf. (3,5-/-Pr2C6H2-4-NH2)2CH2 above] give, on treatment with 2,6-diacetylpyridine, oligomeric polyimines that can be readily complexed with iron dichloride to afford 47 and 48, respectively (Fig. 14). Notably, on activation with MAO, 47 and 48 are active catalysts for ethylene polymerisation and indeed perform more efficiently at elevated temperatures than those of the original bis(imino)pyridine iron precatalyst 5 [166],... 

Detailed mechanistic studies with respect to the application of Speier s catalyst on the hydrosilylation of ethylene showed that the process proceeds according to the Chalk-Harrod mechanism and the rate-determining step is the isomerization of Pt(silyl)(alkyl) complex formed by the ethylene insertion into the Pt—H bond.613 In contrast to the platinum-catalyzed hydrosilylation, the complexes of the iron and cobalt triads (iron, ruthenium, osmium and cobalt, rhodium, iridium, respectively) catalyze dehydrogenative silylation competitively with hydrosilylation. Dehydrogenative silylation occurs via the formation of a complex with cr-alkyl and a-silylalkyl ligands ... 

Vickery and Vickery [9] have investigated the interference by aluminium and iron in the ion-selective electrode method for the determination of fluoride in plant extracts. They demonstrated that plant ashes may contain sufficient of these two elements to seriously interfere in the determination of fluoride when using the fluoride-selective electrode. In the presence of these metals, the known additions method gives erroneous results, as did that involving the attempted formation of complexes with ethylene diamine tetraacetic acid (disodium salt) or 1,2-cyclohexylenedinitrilotetraacetic acid. 

Photolysis of the arene complexes in the presence of monodentate ligands, e.g. carbon monoxide, leads to new complexes of the type CpFe(L) whereas in pure aprotic solvents, ferrocene and iron salts are formed Investigation of the photo-lytic reaction of an iron arene complex with excess ethylene oxide in methylene chloride solution (Meier and Rhis ) showed that a crystalline crown ether complex (structure shown in Fig. 9) was obtained in high yield. Only traces of dioxane could be detected. 

Several aUcene complexes of iron(O) have been reported, of general formula Fe(CO)4(alkene), where the aUcene can be ethylene, acrylonitrile, maleic anhydride, or methyl methacrylate. In these complexes, the original trigonal bipyramidal structure of the pentacarbonyl is retained with one of the equatorial positions now being occupied by the alkene ligand. The tetracarbonyliron(O) complex of fumaric acid has idealized C2 symmetry and has been resolved into its two enantiomers. ... 

Olefin-coupling reactions of Tj -allyliron complexes with a variety of cationic iron-olefin complexes (ethylene, propene, styrene, etc.) were utilized to give cationic bimetallic complexes with cr,7r-hydrocarbon bridges (80,81). The condensation of simple [FpColefin)]" substrates with Fp(allyl) precursors was extended to the reaction with Fp(l,3-butadi-ene)+. Initial attack at C-1 or C-4 leads to the formation of dinuclear complexes with cr-coordinated and 7r-coordinated Fp fragments, which by subsequent intramolecular condensation could give either cyclohexenyl or cyclopentenyl intermediates. Attack at C-2 yields a dinuclear complex incapable of further intramolecular reaction [Eqs. (6-8)]. 

Lehn and coworkers have designed many double-helical compoimds. Copper(I), cobalt(II) and iron(II) were allowed to complex with the ethylene-bridged bis(bipyridine) (10) and bis(phenanthroline) (11) to examine the stereochemical preferences of the metal ions. When ligand (10) was treated with copper(I), a complex of 2 2 stoichiometry (molecular weight confirmed by... 

A correlation of a high thermal stability with a high ionization potential for a olefin has been observed with iron (O)-olefin complexes of the type Fe(CO)4-(olefin) 96> i.e. poor donor but good acceptor properties increase the stability of the complex. The acrylonitrile complex is one of the most stable, the ethylene complex the least stable and the complexes of styrene or vinyl chloride are of intermediate stability. 

Ethylene sulfite reacts with metal carbonyls such as manganese and chromium to form a complex in which the sulfur atom functions as an electron donor and is directly attached to the metal center (83 and 84) (65CB2248). In contrast, 4-vinyl cyclic sulfite reacts with iron nonacarbonyl to form a ir-allyliron complex 85, with the extrusion of SO2 (90SL224, 90SL331). Some of these reactions are summarized in Scheme 20. 

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