An improved synthesis of 1,2,3,4,5-pentamethylcyclopentadiene

Crystal‐Packing‐Induced Antiferromagnetic Interactions of Metallocenes: Cyanonickelocenes, ‐cobaltocenes, and ‐ferrocenes

“…The extended Hückel calculations were carried out with the program package CACAO, version 4.0. [47] Materials: All reagents were commercially obtained except for the following, which were synthesized according to literature procedures: Li(C 5 Me 5 ), [48] K(C 5 H 4 CN), [18] Tl(C 5 H 4 CN), [17d] FeCl 2 ·1.5 THF, [49] NiBr 2 ·1.5 THF, [50] [FeCl(C 5 Me 5 )(tmeda)] (tmeda = N,N-tetramethylethylenediamine), [51] [Co(C 5 Me 5 )(acac)] (acac = acetylacetonate), [52] and [Ni(C 5 Me 5 )(acac)]. [53] The solvents were dried by standard methods and freed from dioxygen by distilling under a stream of dinitrogen.…”

Bis(pentamethylcyclopentadienyl)-Substituted Phosphanes: Synthesis and Structure

“…Treatment of PCl 3 /PBr 3 with 2. 5 Starting from these halogenophosphanes 2a and 2b a variety of previously unknown bis(Cp*)phosphanes could be equivalents of Cp*Li [10] [14] at 0°C in pentane and after stirring for 10 h affords the desired halogenobis(Cp*)phos-obtained by a nucleophilic displacement reaction. There- responding (methylthio)phosphane 6 could be obtained at bility of the nucleophile.…”

Alkali and Alkaline Earth Metal Complexes Ligated by an Ethynyl Substituted Cyclopentadienyl Ligand

“…Compared to the sodium compound 1 and potassium compound 2, the C≡C bond stretching frequency in the IR spectrum is shifted to a slightly lower wavenumber (2108 cm −1 ). In the 1 H and 13 C NMR spectra of 3 in THF-d 8 , two sets of signals were identified, although single crystals of 3 were used for these studies. In the 1 The calcium complex 3 crystallizes from toluene in the monoclinic space group P21/n with half of a molecule in the asymmetric unit.…”

“…The alkali metal cyclopentadienyls are generally available either by deprotonation of cyclopentadiene with an alkali metal base such as M{N(SiMe 3 ) 2 }, MH, MOtBu, MOH or the alkali metal itself [5,6]. Some years ago, we showed that sodium and potassium cyclopentadienyl is most conveniently prepared in a one-pot synthesis directly from alkali metals with neat dicyclopentadiene at elevated temperature [7,8]. Especially in the chemistry of electron poor metals, cyclopentadienyl is often used in the form of its permethylated derivative pentamethylcyclopentadienyl η 5 -CpMe 5 (Cp*) [8,9], because of the higher solubility of the corresponding metal complexes and the enlarged steric demand of the ligand, which prevents polymerization.…”

“…Some years ago, we showed that sodium and potassium cyclopentadienyl is most conveniently prepared in a one-pot synthesis directly from alkali metals with neat dicyclopentadiene at elevated temperature [7,8]. Especially in the chemistry of electron poor metals, cyclopentadienyl is often used in the form of its permethylated derivative pentamethylcyclopentadienyl η 5 -CpMe 5 (Cp*) [8,9], because of the higher solubility of the corresponding metal complexes and the enlarged steric demand of the ligand, which prevents polymerization. Furthermore, other derivatives of cyclopentadienyl are easily accessible and increase the versatility of the cyclopentadienyl ligand [10][11][12].…”