Nonacarbonyl, diiron, react with

The strained-ring compound 1,1-dimethyl-l-silacyclobutane (which may be regarded as an olefin of organosilicon chemistry) reacts with diiron nonacarbonyl in benzene at 6°-20°C as shown in Eq. (100) (89). (There is here some analogy with the reactions of transition metal complexes with strained hydrocarbons, which often produce valence tautomerization.) The... 

Various substituted silacyclopentadienes react with iron or cobalt carbonyl compounds to give stable i 4-silacyclopentadiene complexes. Thus, with iron pentacarbonyl, reaction occurs at 150°-200° in an autoclave, with Fe2(CO)9 at 40°-60°, and with Fe3(CO)12 at 80° (20, 21, 49, 132) the same complex can be obtained from a dibromosilacyclopen-tene and diiron nonacarbonyl, under mild conditions (19) ... 

Several transition-metal complexes of cyclobutadiene have been prepared, and this is all the more remarkable because of the instability of the parent hydrocarbon. Reactions that logically should lead to cyclobutadiene give dimeric products instead. Thus, 3,4-dichlorocyclobutene has been de-chlorinated with lithium amalgam in ether, and the hydrocarbon product is a dimer of cyclobutadiene, 5. However, 3,4-dichlorocyclobutene reacts with diiron nonacarbonyl, Fe2(CO)9, to give a stable iron tricarbonyl complex of cyclobutadiene, 6, whose structure has been established by x-ray analysis. The 7r-electron system of cyclobutadiene is considerably stabilized by complex formation with iron, which again attains the electronic configuration of krypton. 

Substituted methylenecyclopropanes react with diiron nonacarbonyl to give trimethylenemethane and 1,3-diene iron tricarbonyl complexes . Theoretical analysis of the former... 

Another synthetically useful carbon bond-forming reaction involves reaction of diiron nonacarbonyl with halo-carbonyl compounds. Noyori found that a,a -dibromoketones (498) react with diiron nonacarbonyl [Fe2(CO)9] to give an iron stabilized alkoxy zwitterion (499). The intermediate Jt-allyl iron species reacts with alkenes in a stepwise manner (initially producing 500) to give cyclic ketones such as 501, 23 and the product is equivalent to the product of a [3-t2]-cycloaddition with an alkene (sec. 11.11). This cyclization method is now known as Noyori annulation. This reaction is related to the Nazarov cyclization previously discussed in Section 12.3.C. Enamines can react with 498, but the initially formed enamino ketone product eliminates the amino group to form cyclopentanone derivatives. Intermediates such as 499 may actually exist as cations hound to a metal rather than as the alkoxide-iron structures shown.323b-d noted that Zn/B(OEt)3 is... 

The same ring-fused selenines also react with diiron nonacarbonyl to afford diiron selenolates 100 (Equation 28) <1999JCD791>. 

The use of sonolytic activation of Fe2(CO)9 in an inert solvent has proved to be a general process in the synthesis of a large number of (Ti-allyl)tricarbonyliron lactone complexes and provides an alternative route to those already established in the literature. Diiron nonacarbonyl failed to react with alkenyl epoxide (over a period of up to two weeks) in the absence of ultrasonication. Sonication may aid the breakdown of the diiron nonacarbonyl allowing generation of the highly reactive, coordinatively unsaturated tetracarbonyl iron species which after initial complexation to the double bond of the alkenyl epoxide can form the lactone complex. other pathways cannot, however, be ruled out. 

Diiron nonacarbonyl reacts with sodium metal in liquid ammonia to give a carbonylate anion. 

In contrast to 8, germole 15 is stable in the monomeric state, thanks to steric shielding by the bulky mesityl groups (see Section IILA.l). It reacts, nevertheless, with maleic anhydride and diiron nonacarbonyl. 

When tellurophene was reacted in benzene with 2,4-dibromo-3-pentanone in the presence of diiron nonacarbonyl in a sealed tube for six days at 40u, three bicyclic addition products and one substitution product were identified by NMR spectroscopy4. 

Troponoids (5, 222-223). The reaction of a,a -dibromo ketones with diiron nonacarbonyl to generate an oxyallyl-Fe(II) species originally suffered one limitation only secondary and tertiary dibromo ketones reacted satisfactorily. For example, reaction of a,a -dibromoacetone, BrCH2COCH2Br, fails. Noyori et al. have presented a solution to this limitation. The reaction is carried out with a polybromo ketone and the bromine atoms in the adduct are removed with Zn-Cu couple. The synthesis of 8-oxabicyclo[3.2.11oct-6-ene-3-one (1) is... 

Diiron nonacarbonyl and the complexes TpM( = CR)(CO)2 react to afford a family of species TpMFe(/i-CR)(CO)5 (M = W, R = Me, C6H4Me-4 > M = Mo, R = C6H4Me-4" ) with an unsaturated 32-valence electron count in which the M = C bond effectively functions as a four-electron donor to iron. 

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