Cyclopentadienyls alkyls

Several cyclopentadienyl(alkyl)metal carbonyl derivatives have reacted with acetylenes. In some examples, insertion reactions may also be involved, although the mechanisms have not been investigated. Cyclopentadienyl(methyl)iron dicarbonyl with diphenylacetylene gave a 10% yield of cyclopen tadienyltetra-phenylcyclopentadienyliron 71). 

Cyclopentadienones, in molybdenum carbonyls, 5, 451 Cyclopentadienyl alkenes, with niobium, 5, 76 Cyclopentadienyl-alkoxo complexes, with Ti(IV), 4, 495 Cyclopentadienyl alkyl complexes, with niobium, 5, 66 Cyclopentadienyl-amido complexes, with Ti(IV), via dehalosilylation, 4, 448... 

C-H bond dissociation energies, 1, 298 C-N triple bond additions, 10, 427 C02, ketene, ketenimine complexes, 5, 84 CO and CNR reductive coupling, 5, 66 cyclopentadienyl alkyl and aryls, 5, 66 cyclopentadienyl carbonyl complexes, 5, 64 cyclopentadienyl hydrides, 5, 69 cyclopentadienyl isocyanide complexes, 5, 65 rf-acyl and rj2-iminoacyl complexes, 5, 82 fj3-complexes, 5, 87... 

Two other interesting cyclopentadienyl alkyls are (jj -C5Me5)Cr(CH2SiMe3)2 and [(7/ -C5Me5)2Cr2(7/ -CH2Ph)(/r-... 

While inorganic complexes of osmium in oxidation states +4 through +8 have been known for many years, the study of high-valent alkyl and aryl complexes of osmium is much more recent. The organometallic complexes include homoleptic see Homoleptic Compound) alkyls and aryls, oxo alkyls and aryls, nitrido/imido alkyls and aryls, and cyclopentadienyl see Cyclopentadienyl) alkyls and aryls. The majority of these are complexes of osmium(VI). 

With the exception of the metallation reaction in Eq. (4), little chemistry has been reported for homoleptic lanthanide complexes. With four to six reactive alkyl sites per metal center, these compounds are potentially much more reactive than the bis(cyclopentadienyl)alkyl compounds described in Section IV,B. This is an area of future growth in the organolanthanide held. 

Polypyridine ligands form a wide variety of organometallic species with representatives of cobalt and nickel group. They include carbonyl, alkene, alkyne, diene, cyclopentadienyl, alkyl, aryl. 

For the purpose of assigning oxidation states, organometallic ligands such as cyclopentadienyl, alkyl, and allyl are often considered to be anionic. Thus, the formal oxidation states of the metals in Ti(Cp), RjTa (R = Bu CH ), and [Ni(allyl)J are Ti, Ta, and Ni + provided the ligands are treated as Cp, R, and. With alkylidene, alkylidyne, and NHC carbenes, the assignment of the oxidation state is a little more complicated. As discussed later, it is best understood in conjunction with the electron counting scheme. 

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