Pentamethylcyclopentadienyl group

Jutzi et al. have studied reactions of bis(pentamethylcyclopentadienyl)tin with very strong acids such as HBF4, HA1C14 or the methyl esters of CF3COOH and CCljCOOH 173,174). In these reactions only one pentamethylcyclopentadienyl group is surprinsingly replaced and a very stable cationic species (Me5C5)Sn+ is formed ... 

After a decade of research the basic principles in the chemistry of decamethylsilicocene (1) seem to be understood. This compound shows the reactivity of a nucleophilic silylene due to the fact that the Tt-bonded pentamethylcyclopentadienyl ligands are easily transferred to a-bonded substituents during the reaction. The steric requirements of these substituents permit reactions with bulky substrates. The migratory aptitude and the leaving-group character of the pentamethylcyclopentadienyl groups... 

Pentamethylcyclopentadienyl group, 17, 20 leaving-group character, 13, 17, 31-32 ligands, 1, 9, 10... 

Since the heavier group 4A elements can engage in pentahapto bonding with cyclopentadienyl and pentamethylcyclopentadienyl groups, we were prompted to investigate the bonding in isoelec-tronic compounds featuring P+ and As+. 

Successful attempts have been made to classify the nature of some of the above species by the use of the pentamethylcyclopentadienyl group, CsMes(Cp ), which it was supposed avoided the possibility of hydrogen transfer from the Cp ring to the metal. Using this modification it has been possible to obtain pure monomeric Cpf Ti as described below this is now best prepared from its dinitrogen complex, through a series of equilibria (39, 44) ... 

Bispentamethylcyclopentadienyltin(II) undergoes protolytic cleavage of one pentamethylcyclopentadienyl group to yield the salt Me5C5-Sn+BF4 as shown in Eq. (31) (23). 

Simple cyclopentadienyls [MCp2] (M = Eu, Yb) can be made by reaction of cyclopen-tadiene with solutions of the metal in liquid ammonia. The initial products are ammines [MCp2(NH3) c], which can be desolvated by heating in vacuo. [SmCp2] is also known. These compounds have been little studied on account of their low solubilities using instead the pentamethylcyclopentadienyl group confers greater solubility in aromatic hydrocarbons like toluene. 

Question 6.13 Why does using the pentamethylcyclopentadienyl group make these compounds more soluble ... 

Transfer of the pentamethylcyclopentadienyl group from phosphorus to nickel and loss of one of the tertiary phosphine ligands, yielding [Ni(P=NBuO(PBu3)Cp ], occurs when the temperature is increased to -5 C.60... 

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