Sodium cyclopentadienyl, reaction with

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). 

Triethyl phosphonoacetate, reaction of sodium derivative with cyclohexanone to yield ethyl cvclo hexy lideneacetate, 46, 45 1 nfluoroacetic anhydride, 46, 98 p,0 0 Trifluorostyrene, 47, 52 Trusopropvl phosphite as reagent in dechlorination of decachlorobi 2,4 cyclopentadienyl, 46, 93 1,3,5-Tnketones, from aroylationof 1,3-diketones, 46, 59 from 4-pyrones, 46, 59 Tnmethylamine oxide, reaction with x-octyl iodide to yield octanal, 47, 96... 

Another example of a complex that obeys the 18-electron rule is ferrocene or bis(cyclopentadienyl) iron. The cyclopentadienyl anion is generated by the reaction of cydopentadiene with sodium, and ferrocene is obtained by the subsequent reaction with ferrous chloride,... 

Trimethylpyrylium perchlorate is a very versatile and useful starting material. Thus its reaction with cyclopentadienyl-sodium has made 4,6,8-trimethylazulene 12 easily available for general studies of the properties of azulenes 18 and for the synthesis of related compounds.14 In addition, pyrylium salts are readily converted to a variety of pyridine derivatives 9 15 as well as to derivatives of nitrobenzene16 and phenol.9 17,18 It is clear that its value as a starting material is such that it is receiving wide use. 

Reaction with cyclopentadienyl sodium yields bis(cyclopentadienyl) tantalum... 

Benzene cyclopentadienyl ruthenium(II) complex 125 undergoes nucleophilic addition at the arene ligand via the addition of sodium borohy-dride or phenyllithium. Reaction with phenyllithium gives the exo-phenyl cyclohexadienyl derivative 249 in 89% yield (154) [Eq. (32)]. 

The earliest work with cyclopentadienyl was reported independently by Kaesz and by Fischer. They carried out reactions using TcCU and sodium cyclopentadienyl in the presence of BELi as a reducing agent. The species Tc(Cp)2H and [Tc(Cp)2H2]+ have been prepared. These compounds are believed to have bent metallocene (see Bent Metallocenes) stractures. The reaction of TcCLi and potassium cyclopentadienyl in THF gives the diamagnetic air-stable Tc(Cp)2Cl, whose stracture is shown in Figure 4. 

Sodium (cyclopentadienyl)dicarbonylferrate, dicobaltoctacarbonyl, and iron pentacarbonyl have been reported to deoxygenate epoxides efficiently to the corresponding alkenes. The reaction with (cyclopentadienyl)dicarbonylfeirate proceeds with inversion of stereochemistry, whereas Fe(CO)5 shows low stereoselectivity. Both Co2(CO)8 and Fe(CO)s are applicable to epoxides having carbonyl groups (equations 45 and 46). 

The reaction with (cyclopentadienyl)dicarbonylferrate can be directed to give either trans- or m-al-kenes simply by changing the reaction conditions. Thus, reaction with ci.r-stilbene oxide followed by treatment with sodium iodide in acetone gives m-stilbene, whereas only rranf-stilbene is obtained when the reaction is prepared at room temperature and is heated under reflux in THF (equation 47). Although deoxygenation of terminal epoxides proceeds very rapidly, internal epoxides require longer times. Consequently, as in equation (48), selective reduction of diepoxides can be carried out. 

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-... 

The THF in UCI2H2BPZ2THF could easily be replaced by pyridine, giving a dark blue compound. Treatment of a solution of the THF complex in toluene with sodium cyclopentadienyl gave a red-brown solution whose UV/vis spectrum was different from that of the U(III)cyclopentadienyl THF adduct though Still characteristic of a U(III) compound. The same reaction in THF solution, however, did yield a U/f sHslsTHF solution 290). 

The reaction of iodomethylcyclopropane with sodium (cyclopentadienyl)(dicarbonyl)iron in tetrahydrofuran produced a 70 30 mixture of cyclopropylmethyl- and but-3-enyl(cyclopen-tadienyl)(dicarbonyl)iron 1/2. When bromomethylcyclopropane was used the relative amount of cyclopropane product increased to > 97 3. ... 

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