C5H5, cyclopentadienyl

This all explains the nature of failures of the DFT based methods in those cases, when correlations substantially come into play as in e.g. d -iron (II) ferrocene molecule. Here the errors even of advanced DFT methods become catastrophic. For example, in Ref. [86] the calculated enthalpies of dissociation of ferrocene to the free Fe + ion and two Cp anions (Cp = C5H5 - cyclopentadienyl) depending on the functional used appear to be by 3-4 eV smaller than the experimental value. The reason is transparent... 

II,A,4) has shown that infrared spectra are not necessarily indicative of the presence of only (tj-C5H5), cyclopentadienyl ligands. We believe that... 

R = alkyl, (acac) = acetylacetonate, X = halogen, HPT = hexamethyl phosphoric triamide, C5H5 = cyclopentadienyl. Source Data from Ref. 3. 

Structures 23.1a and 23.1b show two representations of an [t -C5H5] (cyclopentadienyl, Cp ) ligand. For clarity in the diagrams in this chapter, we adopt 23.1b and similar representations for 7r-ligands such as r -C3H5 and... 

M(ti -C5H5)(CO)2(ii2-B2H5) (C5H5 = cyclopentadienyl), a class of species related to the preceding, has been discovered for M = Fe and Ru. They are prepared by treatment of K[M(t 5-C5H5)(CO)2] in dimethyl ether with a more than twofold molar excess of B2H6 at 196 C. The mixture Is warmed and stirred at -78 C for 20 hours (M = Fe) and at -38"C for four hours (M = Ru). Solvent is removed under vacuum at -78 C. Subsequently, BH3 0(CH3)2 is removed at 0 C (for Fe), and the product sublimes as orange-yellow crystals in 14% yield... 

C5H5 = cyclopentadienyl Ht = terminal hydrogen, H = bridging hydrogen. 

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