Cyclopentadienide, sodium

AIL Schlenk fiask, which is attached to a pressure-release valve, is flushed with nitrogen and charged with dicyclopentadiene (400 mL). Freshly cut sodium metal (10.00 g, 0.435 mol) is added. The mixture is heated for 6 h at 160°C. The solution initially turns blue (around 35°C), but then slowly discolors. At 150°C, a white solid begins to precipitate. When the alkali metal is quantitatively consumed, the dihydrogen evolution stops. To ensure a quantitative conversion, the heating is continued for another 30 min after the dihydrogen evolution ends. The reaction mixture is cooled, and the white residue is collected by filtration, washed with n-pentane (3x50mL), and dried in vacuum. The urueacted dicyclopentadiene (260 mL) can be reused later for the same reaction. Yield 38 g (99%).  

Sodimn cyclopentadienide is white when rigorously pure, but often darkens with use as it is exposed to increasing amounts of oxygen. As long as the color is not too 

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A standard method for prepanng sodium cyclopentadienide (CsHsNa) is by the reaction of cyclopentadiene with a solution of NaNH2 in liquid ammonia Write a net ionic equation for this reaction identify the acid and the base and use curved arrows to track the flow of electrons... 

Nickel plays a role in the Reppe polymeriza tion of acetylene where nickel salts act as catalysts to form cyclooctatetraene (62) the reduction of nickel haUdes by sodium cyclopentadienide to form nickelocene [1271 -28-9] (63) the synthesis of cyclododecatrienenickel [39330-67-1] (64) and formation from elemental nickel powder and other reagents of nickel(0) complexes that serve as catalysts for oligomerization and hydrocyanation reactions (65). 

TC-Cyclopentadienyl Nickel Complexes. Nickel bromide dimethoxyethane [29823-39-9] forms bis(cydopentadienyl)nickel [1271 -28-9] upon reaction with sodium cyclopentadienide (63). This complex, known as nickelocene, 7T-(C3H3)2Ni, is an emerald-green crystalline sandwich compound, mp 173°C, density 1.47 g/cm. It is paramagnetic and slowly oxidi2es in air. A number of derivatives of nickelocene are known, eg, methylnickelocene [1292-95-4], which is green and has mp 37°C, and bis( 7t-indenyl)nickel [52409-46-8], which is red, mp 150°C (87,88). 

Dicyclopentadienedicarboxylic Acid. Sodium cyclopentadienide (10) can be carboxylated to give dicyclopentadienedicarboxyHc acid (11)... 

The cooled contents of the 2S0-ml. flask containing ferrous chloride (Note 6) are added to the cold sodium cyclopentadienide solution while passing a stream of nitrogen through both flasks. The combined mixture is stirred for 1.25 hours at a temperature just below reflux. Solvent is removed by distillation, and the ferrocene is extracted from the residue with several portions of refluxing petroleum ether (b.p. 40-60°). The product is obtained by evaporation of the petroleum ether solution. Ferrocene may be purified by recrystallization from pentane or cyclohexane (hexane, benzene, and methanol have also been used) or by sublimation. The 3ueld is 31-34 g. (67-73%) (Note 7), m.p. 173-174°. 

Under the best conditions, sodium cyclopentadienide gives pale yellow or orange solutions. Traces of air lead to red or purple solutions, as does insufficiently purified solvent, without, however, lowering the reaction yield appreciably. If 1,2-di-methoxyethane is used, in which sodium cyclopentadienide is less soluble than in tetrahydrofuran, white crystals may be obtained at this point. 

Ferrous chloride may be substituted by ferric chloride directly, with a corresponding reduction in yield, since the sodium cyclopentadienide solution will reduce ferric chloride. 

Another type of diazafulvalenes was obtained by the condensation of sodium cyclopentadienide with l,2-dimethyl-3,5-dimethoxy- and -3,5-bis(methylsulfanyl)pyrazolium salts (94AP385). Under mild conditions displacement of MeZ groups in each case led to the diazafulvalenes 58. A... 

Sodium cyclopentadienide, 41, 96 Sodium dichromate for oxidation of alkylarcncs to aromatic carboxylic acids, 43, 80 Sodium iodide, in conversion of 2,4-di-nitrochlorobenzene to 2,4-dinitro-iodobenzene, 40, 34 reduction of peroxide with, 41,... 

Verdet and Stille1 employed brominated poly(phenylene oxide) intermediates in an effort to synthesize more stable catalyst supports containing (cyclopentadienyl)metal complexes. Treatment of poly(oxy-2,6-dimethyl-l,4-phenylene) with N-bromosuccinimide under photolytic conditions produced only the bromomethyl derivative if the D.F. did not exceed 0.35. Subsequent treatment of the bromomethylated polymer with sodium cyclopentadienide afforded the cyclopentadienyl functionalized polymer, 5, but the reaction was accompanied by crosslinking and it was not possible to remove the bromomethyl substituents quantitatively. 

Accompanies the Formation of Thiele s Ester via Reaction of Sodium Cyclopentadienide with Ethyl Chloroformate... 

At the beginning of the 19th century, Thiele [23, 24] reported that carbonation of sodium cyclopentadienide (37) affords a cyclopentadienecarboxylic acid dimer whose structure subsequently was firmly established as 38 ( Thiele s Acid, Scheme 12) via chemical [25] and spectroscopic [26] methods. 

The first weU-characterized organometallic compounds of the lanthanides or actinides were the tricyclopentadienides of various lanthanide ions S3mthesized by Birmingham and Wilkinson in 1954 (97—98). Anhydrous metal chlorides were reacted with sodium cyclopentadienide in tetrahydrofuran as follows ... 

By controlling the stoichiometry of the reaction between lanthanide trichlorides and sodium cyclopentadienide it is possible to replace the chloride ions stepwise. Equihbria are rapidly established, so the addition of Ln(C5H5)3 to one or two equivalents of LnCls will produce M(C5H5)2C1 and M(C5H5)Cl2, respectively. The dichlorides are known only for the lanthanides from samarium to lutetium and are obtained from THF solutions as tris-THF adducts. 

The present procedure Is a modification of the method previously reported. While the overall yield is similar, the method described here is simpler in that it avoids a cumbersome transfer of the sodium cyclopentadienide solution. 

Ruthenocene has been prepared in 20% yields by reaction of cyclopentadienylmagnesium bromide with ruthenium(III) acetyl-acetonate.8 More recently,4 the compound has been made in 43-52% yield by treatment of sodium cyclopentadienide with ruthenium trichloride in tetrahydrofuran or 1,2-dimethoxyethane. 

Allylic alkylationThis Pd(0) complex, in combination with a small quantity of bis(diphenylphosphino)ethane, is more effective than PdIPfQ.HOjL for alkylation of allylic acetates with the anion of dimethyl malonate. It also permits use of sodium cyclopentadienide as a nucleophile. 

With a Grignard reagent, 1-methylquinolinium ions give products of type (284). A notable reaction of this class is that between the pyridine-sulfur trioxide complex and sodium cyclopentadienide (286)... 

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