Cyclopentadiene molybdenum

Perhaps chemists will be able to mimic nature without duplicating the iron-sulfur-molybdenum structure. For example, a zirconium complex with tetramethyl cyclopentadiene can bind dinitrogen in a manner that breaks the NON bond, as shown below. Treatment with hydrogen gas results in formation of small amounts of ammonia. Although the yields are too low to make this a viable commercial process, researchers hope to make the process more efficient through chemical modifications and changes in conditions. 

C4H 2OSi, Silane, methoxytrimethyl-, 26 44 CH4N, Propane, 2-isocyant-2-methyl-ruthenium complex, 26 275 C][l,4]-dithiin-2-thione, 26 389 CHfc, 1,3-Cyclopentadiene cobalt complex, 26 191-197, 309 chromium, molybdenum, and tungsten complexes, 26 343 iron complex, 26 232-241 mercury-molybdenum-ruthenium complex, 26 333... 

Upon UV irradiation in hydrocarbon solution, the hexacarbonyls of chromium, molybdenum, and tungsten react differently with conjugated dienes like 1,3-butadiene (la), ( )-l,3-pentadiene (lb), 2-methyl-1,3-butadiene (lc), ( , )-2,4-hexadiene (Id), ( )-2-methyl-l,3-pentadiene (le), 2-ethyl-1,3-butadiene (If), or 1,3-cyclohexadiene (Ig). Chromium hexacarbonyl (2) yields, with the acyclic dienes la-lf, tetracarbonyl-r/2-dienechromium(0) complexes (3a-3f) in a smooth reaction (8-10). With 1,3-cyclohexadiene, in addition to 3g, dicarbonylbis(>/4-l,3-cyclohexadiene)chromium(0) (4g) is obtained [Eqs. (7) and (8)j. During chromatography on silica gel, the 1,3-cyclohexadiene complex 3g dismutates readily to [Cr(CO)6] and 4g [Eq. (9)]. Under the same conditions with 2 1,3-cyclopentadiene (lh) yields, in a hydrogen-transfer reaction, the stable dicarbonyl- / 5-cyclopentadienyl-r/ 3-cyclopent-enylchromium (5) (11-13) [Eq. (10)]. 

With CO, a fast addition reaction and transfer of the acetyl group from the molybdenum to the rj4-1,3-cyclopentadiene ligand is observed, and the red endo isomer of 94, [(>75-C5H5)Mo(CO)2to4-end0-C5H6COCH3)] (96), is formed in high yields [Eq. (52)]. Trimethylphosphite releases the y4-i,3-... 

Bis[cyclopentadienyl]bis[arenetellurolato]molybdenum compounds were obtained as quite air-stable, brown solids from bromomagnesium arenetellurolates and bis[cyclopentadien-yl]molybdenum dichloride2. 

The anion Mo(CO)3C5H5 has been prepared by the reaction of the cyclopentadienyl anion with molybdenum hexacarbonyF- and by the reaction of dicyclopentadiene mth molybdenum hexacarbonyl to form [CoH5Mo(CO)3]2, followed by reduction of the latter compound with sodium amalgam. In view of the simplicity of preparing cyclopentadienylpotassium (by deprotonation of cyclopentadiene with potassium hydroxide), the former method is preferable, and is described below. The Mo(CO)3C6H5 anion may be converted to the hydride HMo-... 

Chromium forms a cyclopentadienyl compound similar to ferrocene (p. 499). Cyclopentadienyl sodium reacts with anhydrous chromium (I I) chloride in tetrahydrofuran to give red (C5H5)2Cr. By oxidising this, compounds containing the (C5H5)2Cr+ ion are easily obtained (Cotton and Wilkinson, 1954). When cyclopentadiene mixed with molybdenum or tungsten carbonyl is passed through a tube heated to 300 the dicyclopentadienyl hexacarbonyl is formed (Wilkinson, 1954) ... 

An alternative method of preparation of Mo(ri -C5H5)2H2 employs metal vapor synthesis, in which molybdenum atom vapor and cyclopentadiene react directly under a high vacuum. Yield ca 50%. [44]. 

C,2H, )N2, Azobenzene, cobalt and palladium complexes, 26 175,176 manganese complex, 26 173 C,2H N, Pyridine, 2-(phenylmethyl)-, palladium complex, 26 208-210 C,2H, P, Phosphine, diphenyl-, manganese complex, 26 158,226-230 ruthenium complex, 26 264 C 2H,2, Toluene, a-2,4-cyclopentadiene-l-yl-, chromium, molybdenum and tungsten hexacaibonyl complexes, 28 148... 

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