Manganocene

The actual nature of the ground state for manganocene has been a matter of some debate for a considerable time, with early esr (66) and magnetic moment (67) measurements being interpreted in terms of a high-spin, 6 +(ct n2 52) ground level, although the... 

In a similar manner to manganocene, cobaltocene is easily oxidized to the corresponding cobaltocenium ion [Co(f/5-C5H5)2]+, which, as illustrated in Figure 48, exhibits two distinct chemically reversible reductions corresponding to Coni/Con and Con/CoI.88... 

Manganese forms a large number of mononuclear complexes in oxidation states II, III, and IV with acyclic and other common ligands. The complexes primarily are six-coordinate species with octahedral or pseudo-octahedral geometries. Some exceptions to this categorization are the tetraoxo anions in oxidation states V, VI, and VII and the manganocenes. Table 1 contains electrochemical data for representative redox couples in which the Mn coordination environment remains invariant with oxidation state. Many entries are for homoleptic complexes, but some species with mixed... 

In the cases of chromocene and manganocene, alternate sets of ionic states are presented because of the ambiguities regarding the molecular ground state. 

Fig. 21. Hc(l) UPS of manganocene, 1, l -dimcthylmanganoccne, cobaltocene, and nickel-ocene. (From Ref. 122.)...

The traditional names ferrocene, manganocene, ruthenocene, nickelocene, etc. are given to the respective bis(ri5-cyclopentadienyl)metal complexes. Ocene names should not be coined for isoelectronic species such as chromocene for bis(ri6-benzene)chromium, for structurally analogous... 

Fig. 20. Changes in orbital occupancy accompanying spin-state crossovers in manganocene.

Fic. 22. Spin crossover temperatures for manganocenes as a function of alkyl groups. Data for [MnCp,], [Mn(C5MeH4)2]. and IMniCyi-PrljH,) .], from Refs. 203, 169, and 179, respectively. 

In addition to the extensive chemistry of ferrocene, other metallocenes undergo some of the same types of reactions. Manganocene, Mn(C5H5)2, is prepared by the following reaction that is carried out in tetrahydrofuran (THF) as a solvent ... 

Manganocene (d5 Mn") is also anomalous in that it exists in a thermal equilibrium between spin states with 1 and 5 unpaired electrons. MnCp 2, however, has one unpaired electron whilst [MnCp 2p is diamagnetic. 

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