Metal tricarbonyl-cyclopentadienyl

Fig. 14 Metal carbonyl anticancer and diagnosis compounds a a dicobalthexacarbonyl-alkyne agent b a metal tricarbonyl-cyclopentadienyl species...

We studied allyliron tricarbonyl halides obtained earlier by Plowman and Stone (427) and by others (428, 429). The compounds were taken because (1) they are complexes of iron, the metal whose cyclopentadienyl derivatives were under thorough study in our laboratories, and (2) octahedral 77-allyl complexes were scarcely known at that time, so it was challenging to compare them with the square-planar 77-allyl complexes which were extensively studied in the USSR as well as elsewhere. 

Transition metal organometallic complexes like dicarbonyl cyclopentadienyl iron [128], tricarbonyl cyclopentadienyl manganese [129] and iron-arene complexes [130,131] have also been reported as photoinitiators for photochemical crosslinking of cyanate esters. Photosubstitution of carbonyl groups by -OCN during irradiation initiates the reaction in the former case whereas photochemical dissociation of arene triggers it in the latter system. 

Me3SiPPh2 assists in the insertion of CO into the Mn-R bond or RMn(CO)5 (R = alkyl or aryl) followed by silyl migration to oxygen. With Mn(CO)5H, however, only cis-substitution by the phosphine occurs, while with the cyclopentadienyl metal tricarbonyl hydrides, silylation occurs at the metal (Scheme 23)92. 

Methylcyclopentadiene readily undergoes reaction with metal carbonyls 47) and even 1,3-diphenylcyclopentadiene reacts with iron carbonyl 4S). A novel method for obtaining a ferrocene with one substituted ring, is the reaction of 1,3-diphenylcyclopentadiene with the dimer of cyclopentadienyl-iron dicarbonyl at 170° C to produce 1,3-diphenylferrocene in 15% yield. Other substituted cyclopentadienes which have been used are tetraphenyl-cyclopentadienone in the preparation of tetraphenyl(hydroxy)cyclopenta-dienylmanganese tricarbonyl 49) and indene in the preparation of the dimer of indenylmolybdenum tricarbonyl (50). A variety of substituted fulvenes have been used in the preparation of substituted cyclopentadienyl metal tricarbonyl compounds of Cr, Mo, and W (57, 52). This latter reaction proceeds best in the presence of a solvent, such as 1,2-dimethoxyethane, to permit easy abstraction of hydrogen. 

The salt which is formed may then be treated with acetic acid to yield cyclopentadienyl metal tricarbonyl hydride or with alkyl halides to form alkyl derivatives. 

Despite a common perception that organometallic chemistry essentially belongs in the province of catalysis rather than in vivo applications because of high reactivity of metal carbon bonds, certain organometallic species have very high kinetic stability. Indeed, this point is highlighted by the present wide application of the isonitrile complex Tc(ses-tamibi), [Tc(2-methoxyisobutylisonitrile)6]+, in myocardial imaging. Rhenium tricarbonyl and cyclopentadienyl complexes offer further ex-... 

Reactions of cyclopentadienyl- and (pentmethylcyclopentadienyl)iron dicarbonyl 2-alkynyl complexes as well as cyclopentadienylmolybdenum tricarbonyl 2-alkynyl complexes with 4,5-diphenyl-3,6-dihydro-l,2-dithiin 1-oxide 111 were shown to yield transition metal-substituted five-membered ring thiosulfinate esters 112 in moderate to excellent yields (Scheme 27) <19910M2936, 1989JA8268>. These reactions are formal [3-1-2] cycloadditions. When... 

Still other 7r-cyclopentadienyl-metal compounds have been shown to undergo acylation. The successful acylation of cyclopentadienylmanganese tricarbonyl has opened up yet another interesting aromatic-type system for exploration (9, 10, 11, 13, 20, 45, 99). An example of this type concerns the benzoylation of methyl-cyclopen tadienylmanganese tricarbonyl (XII) (10, 45). Both l-methyl-2-ben-zoylcyclopentadienylmanganese tricarbonyl (XIII) and the corresponding 1,3-isomer (XIV) are readily obtained. 

A number of readily reversible cr-7r rearrangements have been observed wherein a labile ligand such as carbon monoxide is lost by pyrolysis or photolysis, producing a coordinatively unsaturated metal center, which then regains coordinative saturation by means of a tr-n rearrangement. For example, irradiation of o--alkyl-7r-cyclopentadienyl-molybdenum tricarbonyl (15) produces the rr-allene complex (16) (25). These... 

Several monosubstituted derivatives have been made in a similar manner, except that a unidentate ligand is used in place of the carbon monoxide, namely NH3, N2H4 (88) C2H4 (75) PPh3, AsPh3, CH3CN (231). Alternatively, substituted monooleiin derivatives have been synthesized by protonation of the metal a-allyl 7r-cyclopentadienyl tricarbonyl (55, 112). 

The methylcyclopentadienylmolybdenum tricarbonyl synthesis illustrates how a cyclopentadienylpotassium solution can be prepared and then used to prepare a typical transition metal-cyclopentadienyl complex. By analogous procedures, one can prepare a wide variety of metal complexes of the anions of cyclopentadiene, indene, etc. The ferrocene and nickelocene syntheses illustrate how the procedure can be adapted to the... 

In (r-methyl-ir-cyclopentadienylmolybdenum tricarbonyl, the methyl group is attached to the molybdenum by a metal-to-carbon tr-bond, and the cyclopentadienyl group is attached by TT-type bonding, as in sandwich compounds. The material forms yellow crystals, m.p. 124° (decomp.), that are soluble in organic solvents and slowly oxidized by air. Purification is readily effected by vacuum sublimation. The infrared and n.m.r. spectra have been described. ... 

In solution, the cyclopentadienyl tricarbonyl dimers [CpMo(CO)3]2 and [CpW(CO)3]2 react to form the heterobimetallic complex Cp(CO)3Mo-W(CO)3Cp. However, the reaction does not go to completion a mixture results in which the [CpMo(CO)3]2 and [CpW(CO)3]2 are in equilibrium with the mixed metal compound. The abundance of the three organometallic complexes is governed statistically by the number of CpMo(CO)3 and CpW(CO)3 fragments present. If 0.00100 mmol of [CpMo(CO)3]2 and 0.00200 mmol of [CpW(CO)3]2 are dissolved in toluene until equilibrium is achieved, calculate the amounts of the three organometallic complexes in the equilibrium solution. (Reference T. Madach and H. Vahrenkamp, Z. Naturforsch., 1979, 34b, 573.)... 

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