Cyclopentadienyl-cobalt dicarbonyl

In a similar manner, silacyclopentadienes react with cyclopentadienyl-cobalt dicarbonyl to give an - -complex (49, 138) ... 

Reaction of thietes with iron carbonyls or cyclopentadienyl cobalt dicarbonyl affords thioacrolein complexes 57 and 58. On gentle heating or... 

Toluene and THF were distilled from sodium benzophenone ketyl before use. Tantaliun bromide, niobiiun bromide, niobium chloride, cyclopentadienyl cobalt dicarbonyl, bis(l,5-cyclo-octadiene)diiridium(I) dichloride, tetraphenyltin, and tri-phenylphosphine were Aldrich products of the highest purities. All other reagents and solvents were purchased from Aldrich and used as received. 

Intramolecular [2 + 2 + 2] cycloadditions belong to the same type of valence isomerization as those of 1,5-unsaturated compounds to cyclobutanes.70 The cobalt-mediated cyclization of l-en-5-ynes stereoselectively converts enediynes directly to bicyclo[4.2.0]hexa-l,3-dienes, as single diastereomers, when a stoichiometric amount of dicarbonyl(cyclopentadienyl)cobalt is used. This cyclization90 has a high efficiency (92%). An example is the synthesis of the protoilludane framework 23 from the enediyne precursor 22.71... 

Dicarbonyl( 75-cyclopentadienyl)cobalt may be synthesized from Co2(CO)8 (Ref. 5) or purchased from Strem or Pressure Chemicals. Diphenyl-acetylene (Farchan, commercial grade) can be used without purification. 

Dicarbomethoxynorbomene, 578 Dicarbonyl(cyclopentadienyl)cobalt, 161-162 Di-[x-carbonylhexacarbonyldicobalt, 162-163 Dichloroacetylene, 552 Dichlorobis(cyclopentadienyl)titanium, 163—... 

Rosenblum et al. 386> reported a very elegant synthesis of cyclobutadiene iron tricarbonyl starting from oc-pyrone. The corresponding reaction with cyclopentadienylcobalt dicarbonyl produces cyclobutadiene-(cyclopentadienyl)cobalt 88S>. 

A synthetically important breakthrough in the application of transition metal catalyzed alkyne trimerization was made in the selective cocyclotrimerization of diynes with silylated alkynes using dicarbonyl(t/5-cyclopentadienyl)cobalt as precatalvst. The silylated alkynes do not show any tendency to undergo self-trimerization thus, depending on the nature of the chain between the two alkyne units, benzo-fuscd carboeyclic or heterocyclic rings are formed3,31 34... 

Two general methods have been used for the preparation of cyclopentadienylcobalt dicarbonyl the reaction between dicobalt octacarbonyl and cyclopentadiene and the reaction of bis (cyclopentadienyl) cobalt with carbon monoxide at elevated temperatures and pressures. The method given here is a modification of the second method, and as in the preparation of cyclopentadienylvanadium tetracarbonyl described above, avoids isolation of the intermediate pyrophoric bis(cyclopentadienyl)metal derivative. 

C7H5Cl2CoHg02 Dicarbonyl(TT-cyclopentadienyl)cobalt - mercury(II) chloride, 38B, 775... 

C2 6H2 2C02Mn04P, Dicarbonyl-cyclopentadienyl-manganese-M3 (benzyl-phosphido)-bis(carbonyl-cyclopentadienyl-cobalt), 45B, 980 C26H25F12N3P2V2, Bis(fulvalene)bis(acetonitrile)divanadiumUII)(V-V) bis(hexafluorophosphate) acetonitrile, 45B, 980 C2 6H2 sN2Ti, 4-Methylene-3,7,8-trimethyl-1,10-phenanthrolinebis( t -cyclopentadienyl)titanium, 46B, 902 C2 6H2 sNijTi 2, M-Pyrazole-bis(Ty -cyclopentadienyl)titanium(III), 44B, 770... 

Herrmann, W.A., Steffi, 1., Ziegler, M.L. and Weidenhammer, K. (1979) Funfgliedrige Cobaltacyden durch Carben-Addition an Dicarbonyl-(r -cyclopentadienyl)cobalt Chemische Berichte, 112, 1731-1742. 

The fused system 3,4-bis(trimethylsilyl)benzocyclobutene (7) has been obtained by cyclotrimerization of the alkyne l-trimethylsilylhexa-l,5-diyne in the presence of dicarbonyl(cyclopentadienyl)cobalt and converted (by Bu"Li) into l,2-dihydrocyclobuta[c]benzyne, which was trapped as the adduct (8). 

Related Reagents. Dicarbonyl(cyclopentadienyl)cobalt(I) Octacarbonyldicobalt-Diethyl(methyl)silane-Carbon Monoxide Sodium Tetracarbonylcobaltate. 

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... 

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