Pyrophoric block metals

Compounds of these metals involving either a- or tt-bonds to carbon are generally much more reactive to both air and water than those of the d-block metals. Thus there is no lanthanide equivalent of ferrocene, an unreactive air- and heat-stable compound. They are often thermally stable to 100 °C or more, but are usually decomposed immediately by air (and are not infrequently pyrophoric). Within these limitations, lanthanide organometallic compounds have their own special features, often linked with the large size of these metals. 

Despite the extreme air and moisture sensitivity of organo-lanthanoid compounds, this is a rapidly expanding research area. An exciting aspect of organolanthanoid chemistry is the number of efficient catalysts for organic transformations that have been discovered (see Box 25.5). In contrast to the extensive carbonyl chemistry of the J-block metals (see Sections 24.4 and 24.9), lanthanoid metals do not form complexes with CO under normal conditions. Unstable carbonyls such as Nd(CO)g have been prepared by matrix isolation. Since organolanthanoids are usually air- and moisture-sensitive and may be pyrophoric, handling the compounds under inert atmospheres is essential. ... 

Although lacking 7T-bonded compounds in low oxidation states that characterize the d-block elements, the actinides have a rich organometallic chemistry. Their compounds frequently exhibit considerable thermal stability, but like the lanthanide compounds are usually intensely air- and moisture-sensitive. They are often soluble in aromatic hydrocarbons such as toluene and in ethers (e.g., THF) but are generally destroyed by water. Sometimes they are pyrophoric on exposure to air. Most of the synthetic work has been carried out with Th and U this is partly due to the ready availability of MCI4 (M = Th, U) and also because of the precautions that have to be taken in handling compounds of other metals, especially Pu and Np. 

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