Cerium acetylides

Benzyl bromide, Molecular sieve, 2735 Benzyl chloride, Catalytic impurities, 2738 1,2-Bis(chloromethyl)benzene, 2946 Bis(2-cyanoethyl)amine, 2397 Bis(trimethylsilyl) peroxomonosulfate, 2602 Borane -tetrahydrofuran, 0138 Butylmagnesium chloride, 1641 Calcium acetylide, Methanol, 0585 Calcium chloride, 3923 Cerium, Water, 3961... 

Formation of complex 26 by oxidation of the allenylidene-acetylide derivative 25 with cerium(IV) ammonium nitrate merits to be highlighted since 26 represents a unique example in which two allenylidene ligands are bonded to a metal (Scheme 10) [181]. 

McColm et al. (1977) considered that the eomposition ranges seem to be related to the amounts of R(IV) found in the respective nitrides and carbides (Lorrenzelli et al. 1970, Atoji 1962). In the cerium systems, Ce(IV) is present up to 70%, while in the praseodymium case the amount is less and in the lanthanum system the higher oxidation state is absent. This suggests that Ce(IV) and Pr(IV) do assist in preventing the catenation that leads to acetylide ion formation. However, the reviewers suggest that this factor is probably minor while the size factor of the rare earth atom is essential. 

In this article the term organometallic compound includes alkyl and aryl derivatives of the rare earths—the transition metals of group III, scandium, yttrium, lanthanum and the lanthanides cerium to liitetium with covalent metal-to-carbon a-bonds, as well as the so-called 77-complexes with more than monohapto metal-to-carbon bonds, for example cyclopentadienyl and olefin complexes, metal acetylides, but not carbonyls, cyanides and isocyanide complexes. Derivatives of scandium, yttrium and lanthanum are included and discussed together with the compounds of the lanthanides, because of many similarities in the synthesis and the chemistry of these organometallic derivatives of the rare earths. 

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