Cyclopentadienylmolybdenum

Most preparations of the intermediate racemic 3-allyl(dicarhonyl)cyclopentadieny molybdenum complexes7 2 start from sodium or potassium tricarbonyl(cyclopentadienyl)molybdate8 9 10 (4) for a simple preparation see ref 11, p 493. The allylation of 4 hy homoallylic halides, such as 4-hromo-l-butene, is accompanied by rearrangement and decarhonylationI2. (Z)-if-2-butenyl(dicarbonyl)cyclopentadienylmolybdenum (5), like other comparable complexes, exists as a mixture of endo/exo- conformers, which interconvert rapidly at room temperature12. 

Tricarbonyl(chloro)cyclopentadienylmolybdenum 6 reacts with 3-bromo-l-propene under phase transfer conditions at 45 °C to give directly the dicarbonyl(j)3-2-propenyl) complex 8 whereas at lower temperature the tricarhonyl(>/I-2-propenyl) complex 7 is obtained14. It was proposed that the carbon monoxide acts as the reducing agent. 

In a more complex type of reaction, propene reacts with methyl trichloro-acetate under the catalytic influence of cyclopentadienylmolybdenum tricarbonyl or cyclopentadienyliron dicarbonyl dimers to give 4-methyl-2,2 -... 

Allylation of aldehydes accompanying alkoxycarbonylation using cyclopentadienylmolybdenum complexes was also applied to butenolactone synthesis.246,247 Intra- and intermolecular cyclization occurred after allylation of the aldehyde to give a-methylene butenolactone derivatives (Scheme 59). 

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... 

The same substituted cations are obtained by the photochemical disproportionation of dimeric 7r-cyclopentadienylmolybdenum tricarbonyl, [CpMo(CO)3]2, with the following ligands PEt3, PPh3, PBu3n, and diphos U5)-... 

Acetylcarbonyl-i/4-l,3-cyclopentadiene- 5-cyclopentadienylmolybdenum (78) is thermo- and photolabile, so one can also expect a high reactivity toward potential ligands. The reactions of carbon monoxide, trimethylphosphite, and several conjugated dienes have been studied in this respect (124). 

Initial experiments by Gibson et al. (77) indicate phase-transfer catalysis to be a promising method for the synthesis of benzyl complexes. Reaction of benzyl bromide with cyclopentadienylmolybdenum tricar-bonyl chloride, under conditions similar to those described for the preparation of o-- and 7r-allyl complexes, afforded the o--benzyl complex (64) in 89% yield. Use of benzyl chloride as substrate results in a considerably... 

C0)3C5H5 "2 or to any of a series of alkyl derivatives, RMo-(CO)3C5H5d The preparation of the methyl compound is described here. iVIany other cyclopentadienylmolybdenum tricarbonyl derivatives are known synthetic methods for some of these are discussed by Pruett. ... 

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. ... 

C. CYCLOPENTADEENYLMOLYBDENUM TRICARBONYL DIMER AND CYCLOPENTADIENYLMOLYBDENUM TRICARBONYL HYDRIDE... 

Cyclopentadienylmolybdenum tricarbonyl dimer has been prepared by oxidation of the hydride C6H6Mo(CO)3H... 

Cyclopentadienylmolybdenum tricarbonyl hydride is a yellow crystalline solid subliming easily at 50° at 0.1 mm. It is quite air-sensitive, darkening noticeably immediately on exposure to air, and therefore it should always be handled and stored under nitrogen. 

Cyclopentadienylmolybdenum tricarbonyl dimer is a red-violet crystalline solid subliming with difliculty at 150° at 0.1 mm. with fairly extensive decomposition. It is spar-... 

C20H1 cFe, 4-endo,6 -endo-Bis(Tr-azulene) iron, 34B, 473 C2oHiBFe2C5, Guaiazulenepentacarbonyldiiron (isomer I), 43B, 1100 C2oHiBFe205f Guaiazulenepentacarbonyldiiron (isomer II), 43B, 1100 C20H20F12MO2OP2 0.5 H2O, M (i rj -Fulvalene)-M hydrido-M hydroxyl-bis(r -cyclopentadienylmolybdenum) hexafluorophosphate hemihydrate, 43B, 1080... 

In the first in a new series of papers the synthesis and characterisation of Cr(II) carbonyl and ferf-butyl isocyanide complexes, such as the structure shown as 24, have been reported. Again the synthesis and characterisation of the di-alkyl(butadiene)cyclopentadienylmolybdenum(III) complexes, such as the complex shown as 25, have been prepared in the reactions of the CpMo(ri -diene)Cl2 (diene = 1,3-butadiene, isoprene, CsHg 2,3-dimethyl-1,3-butadiene, CeHio)... 

Many derivatives of r-cyclopentadienylmolybdenum carbonyls with sulphur ligands are known, e.g. tt-C5H5Mo(CO)2S2CSR [158cz], and the anion [n -C5H5Mo(CO)2S2C2(CN)2]- [158i]. 

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