Cyclopentadienylmetal carbonyls

Because it is so difficult to substitute CpMn(CO)3 thermally, a photochemical method is usually used. 

The cobalt complex CpCo(C0)2 is a dark red liquid, b.p. 139 C/710mm which is rather sensitive to light, heat and oxygen and which is much more reactive 

The iron dimer [CpFe(C0)2]2 is easily prepared by heating pentacarbonyliron in dicyclopentadiene at 140°C. It forms maroon-purple crystals which are only 

Silver tetrafluoroborate in the presence of ligands oxidizes it to cationic species (p. 240). 

The iron—iron distance in the cis and also in the trans isomer is quite long, about 2.53 A, compared with 2.48 A in metallic iron. X-ray diffraction reveals 

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A. Metal carbonyl anions/cyclopentadienylmetal carbonyl anions... 

The reactivity of these metal hydride-metal carbonyl reactions can be correlated with the nature of the reactants in a manner consistent with the proposed mechanism nucleophilic attack by hydride on coordinated CO. Thus reactions involving the highly nucleophilic group IV hydride, Cp gZrHg, are much faster than those of group V metal hydrides. On the other hand, the relatively electrophilic neutral binary metal carbonyls all react with Cp2NbH under mild conditions (20-50° C), whereas more electron-rich complexes such as cyclopentadienylmetal carbonyls (Cp2NbH(C0), CpV(CO) ) or anionic carbonyls (V(CO)g ) show no reaction under these conditions. 

The mass spectra of binuclear cyclopentadienylmetal carbonyl derivatives of chromium and molybdenum provide useful indications of the relative strengths of the metal-metal bonds in various compound types. The mass spectrum of [C5H5Cr(CO)3]2 (S. M = Cr) exhibits no bimetallic ions but only monometallic ions such as CsHsC CO) (n = 3,... 

A more sophisticated approach has been used by Winters and Kiser (199) to calculate the heats of formation of the cyclopentadienylmetal carbonyls C5H5V(CO)4, C5H5Mn(CO)3, and C5H5Co(CO)2 as well as the heats of formation of some of the fragment ions. The heats of formation were calculated for the process... 

New group 4 cyclopentadienylmetal carbonylate derivatives were also reported (equation 62) . 

The possibility of performing metal-catalyzed desulfurization under PTC conditions was first demonstrated for thiobenzophenones. These compounds were reacted with cyclopentadienylmetal carbonyls in a benzene/aq. NaOH system containing a PT agent [189]. Fulvenes and disulfides are formed in the presence of iron complexes (cf. Section 3.2.13). 

Cyclopentadienylmetal carbonyls, -C5H5M(CO)2 and -C5Me5M(CO)2 (M = Rh, Ir) have also been incorporated into zeolites and their interaction with the cage has been investigated. Decarbonylation occurs on heating [284, 285]. 

Tetrametallic cyclopentadienylmetal carbonyls of both iron and ruthenium are known. Prolonged boiling... 

Molecular rotation in the cavity has been discussed for many compounds using nmr(8,9), esr(lO) and Mossbauer spectroscopy(4,5). A complete description of the Mossbauer spectrum for such a case has been given by Gibb(4) for that of the 3 1 clathrate of thiocarbonyl diamide and bis( -cyclopentadienyl)iron(II). Evidence for conformational isomerism has been presented recently based on the ir spectra of y-cyclopentadienylmetal carbonyl complexes such as CpFe(CO) SiCl Me(ll), ip -MeC H Mn(CO) (P(OMe) )(12) and others(13), and on the Mossbauer... 

IR-Active Cs,. Normal Vibrations of the tt-Bonded Cyclopentadienyl Ligands IN Cyclopentadienylmetal Carbonyls ... 

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