Cyclopentadienyl iron dicarbonyl derivatives

CONH2 and COOMe, is discussed on p. 214. Isocyanatomethyl, Fe—CH2NCO and alkoxycarbonyl, Fe—COOR derivatives have also been prepared [55 ]. The tricyanomethyl complex, r-C5H5Fe(CO)2C(CN)3 has been prepared from 7r-C5H5Fe(CO)2Cl using Ag+[C(CN)3] [50]. 

The structure of the molybdenum ethyl complex, 7.15, has been determined by X-ray diffraction [56]. The Mo-C(ethyl) bond length (2-38 A) is found to be the sum of the covalent radius of sp carbon plus half the Mo-Mo distance in the binuclear complex [3r-C5HsMo(CO)3]2. This rather long distance suggests there is considerable /-electron character in the bond. The thermal decomposition of the complexes jr-C5HsMo(CO)3R,  

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Fe(CO)4H2 Iron tetracarbonyl dihydride, 2 243 potassium salt, 2 244 sodium salts, 7 194, 197 [Fe(C204)3]K3-3H20 Potassium trioxalatoferrate(III), 1 36 FeC6Hs(CO)2l Cyclopentadienyl-iron dicarbonyl iodide, 7 110 FeC6H5(CO)2Na Cyclopentadi-enyliron dicarbonyl, sodium derivative, 7 112 [FeC6H5(CO)2]2 Cyclopentadi-enyliron dicarbonyl, dimer, 7 110... 

Several cyclopentadienyl(alkyl)metal carbonyl derivatives have reacted with acetylenes. In some examples, insertion reactions may also be involved, although the mechanisms have not been investigated. Cyclopentadienyl(methyl)iron dicarbonyl with diphenylacetylene gave a 10% yield of cyclopen tadienyltetra-phenylcyclopentadienyliron 71). 

Dicarbonyl(ri5-cyclopentadienyl)iron-alky] complexes represent useful precursors for iron-carbene complexes [47]. For example, iron-carbene complexes are intermediates in the acid-promoted reaction of Fp-alkyl ether derivatives with alkenes to provide cyclopropanes via a [2 + l]-cycloaddition (Scheme 1.16). 

For the preparation of unsymmetrical ferrocenes, two ways by which only mono-substituted derivatives are produced have been suggested. One route starts from iron tetracarbonyl and a substituted cyclopenta-diene the other from monocyclopentadienyl iron dicarbonyl bromide, which on treatment with a substituted cyclopentadienyl lithium is finally converted into the corresponding mono-substituted ferrocene. Experience shows the first method to be more suitable for the preparation of aryl, and the latter method for the preparation of alkyl, derivatives (57). Corresponding work already carried out on substitution in Ru(C5H6)2 and Os CsH5)2 has also been fruitful. It is found that in the Friedel-Crafts reaction with acetyl or benzoyl chloride there is a distinct predominance of mono- over disubstitution as the atomic weight of the central atom increases (47, 72). 

Monolithiated carboiane 12 has been added to protected aldono-1,4- and l -lacttmes such as 13 and 14, and the products deprotected to afiftMd carbohydrate carboranes 15 and 16, reflectively. Some 2 bromo (fx iodo)-2-deoxy sugar derivatives have been treated with a dicarbonyl-(cyclopentadienyl)iron(II) nucleophile affording C-bonded derivatives such as 17-19, and the carbohydrate cobaloximes 20-22 have been prepared from iodides 23-25. ... 

A rather early example for a formal iron-catalyzed [2+2] cycloaddition was reported by Rosenblum et al. in 1982. The reaction of propiolic ester with olefins is catalyzed by the (dicarbonyl)(T -cyclopentadienyl)iron(II) cation (Fp ) (Scheme 4-300). The corresponding cyclobutene derivatives are obtained in moderate yields and excellent stereoselectivity. ... 

In a similar manner, Jt-allyl complexes of manganese, iron, and molybdenum carbonyls have been obtained from the corresponding metal carbonyl halides [5], In the case of the reaction of dicarbonyl(r 5-cyclopentadienyl)molybdenum bromide with allyl bromide, the c-allyl derivative is obtained in 75% yield in dichloromethane, but the Jt-allyl complex is the sole product (95%), when the reaction is conducted in a watenbenzene two-phase system. Similar solvent effects are observed in the corresponding reaction of the iron compound. As with the cobalt tetracarbonyl anion, it is... 

Many other iron complexes (j -alkyls, -acyls, rj -alkynyls, cationic -alkenes, and carbenes) are ultimately derived from either sodium dicarbonyl (cyclopentadienyl)... 

A related reaction was published by Akita et al azide reacts with the cationic cyclo-pentadienyliron complex [(77 -Cp)Fe(CO)2(r/ -Ph-C=C-Ph)] by attacking the central C=C triple bond to form the organoazide derivative dicarbonyl(77 -cyclopentadienyl)(/ ran -l,2-diphenyl-2-azidoethenyl)iron(II) (Figure 12.7). The ran -configuration of the C=C double bond seems to enhance the stability of the vinyl azide as shown by Fowler et al for azido-l,2-diphenylethene. ... 

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