Ferrole complexes

Scheme 3. Formation and structure of iron ferrole complexes under neutral or basic conditions. ...

Reactions of alkynes with iron carbonyl species afford a variety of products (usually with a low selectivity) depending on the structure of the alkyne and the reaction conditions as already described in COMC(1982). Major products are the trinuclear /X3-alkyne clusters with the - 1 and -coordinated alkyne ligands 2, the trinuclear di(/X3-alkyne) complexes 3, the di- 4 and trinuclear ferrole complexes 5, and the diiron flyover complexes 6 (Scheme 1). 

Reactions with hetero-substituted alkynes are also examined. The dipropargylamine, MeN(GH2C=GH)2, reacts with Fe3(CO)i2 to provide a mixture of the bicyclic 4- and 5-type ferrole complexes, 9 and 10, as the major products," " while propargyl alcohols give allenylidene complexes, Fe3(GO)io(/x-C=C=CR2) (R2 = Me2, (GH2)s, Me/Ph) (see Section 6.08.2.3) via dehydration together with the 2- and 4-type complexes. " For a thiopropargyl system, see Chapter 6.07.7.2.2.1. 

The ort o-metalated iron hydride complexes [HFe(CO)2 P(OPh)3 (PhO)2POC6H4 ] with R C=CR (R =Ph, R2 = Mc R = R2 = Mc R =Me, R2 = CH(OEt)2 R =Me, R = CH20H R = R = CH20H) in the presence of hydrated zinc chloride give a series of ferracyclopentendione complexes 203 <2000JOM(612)61>. With phenylace-tylene under similar conditions, the ferrole-type species 204 is formed with structural parameters similar to those... 

In an unusual approach, Rauchfuss and coworkers were able to show tliat Fc3(CO),2 reacts not only with free thiophenes -as described in the preceding section- but also with the n activated thiophene in the rhodium complex Cp Rh(r -T), to yield predominantly a bimetallic product containing a ferrole unit K-bonded to Rh. The reaction was shown to proceed via a stable intermediate containing the T ligand simultaneously bonded t) to Cp Rh and t) to a Fe(CO)4 fragment both complexes... 

By analogy with the behaviour of the iron tricarbonyl complex of benzocyclo-butadiene, formation of ferrole (158) from cyclododeca-l,7-diyne and iron penta-... 

The reactions of iron carbonyls with alkynes however can often lead to a range of products that are difficult to separate. Manning and co-workers have found that photolysis of Fe(GO)3 P(OPh)3l2 with alkynes gives products Fe(GO)2 P(OPh)3 2( 7 -alkyne) 5 via the orthometallated iron-hydride intermediate HFe(GO)2 P(OPh)3 - (PhO)2POG6H4 4. Maleoyl complexes 6 are also formed with internal alkynes. However, the ferrole derivative 7 is obtained by reaction with the terminal alkyne HG=GPh (see Scheme 8). Grystal structures of the complexes 5a and 6c have been determined and confirm their formulations. The alkyne carbon-carbon distance in 5a is 1.274(4) A which lies toward the shorter end of the range of reported carbon-carbon distances of coordinated diphenylacetylene (1.24-1.35 A). 

Formal insertion of CO2 into Fe-C bonds is formed in the reaction of Fe3(CO)i2 with hex-l-en-3-yne. The reaction consists in the splitting of water into its three components, favored by the tic silica used for purification. The final product is, however, a binuclear complex.Related to this behavior is the reaction of Fe3(CO)i2 with l-phenyl-2-propyn-l-ol where the allenylidene complex Fe3(GO)9(/x-GO) C=C=C(H)Ph 4 is obtained first. It reacts with methanol to form a ferrole-like methoxycarbonyl (or acetate) derivative. It has been also observed that similar binuclear complexes can be obtained by reacting Fe3(CO)i2 with propargyl alcohol or propargyl chloride in KOH/CH3OH solutions followed by acidification with HCl GO and methanol activation occurs in this instance to form binuclear methoxycarbonyl derivatives and the open cluster Fe3(GO)io H2GGG(H)G(=0)G[GH2(0)GH3GGH2] 5. ... 

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