Organotransition metal chemistry. Alkyl and alkylidene derivatives. Complexes of alkenes and alkynes

Abstract

At the time when the alkyl and aryl derivatives of the Main Group elements were being discovered and their chemistry developed, little progress was made in the search for corresponding compounds of the transition elements. In general, reactions of Grignard reagents with anhydrous transition metal halides yielded mixtures of hydrocarbons and metal-containing residues from which no organometallic compounds could be isolated. The few exceptions were thought to be anomalies, rather than indications of a whole new area of knowledge yet to be explored. In 1907 Pope and Peachey in Cambridge, for example, isolated trimethylplatinum halides, [Me₃PtX]₄, from the reaction of methyl Grignard reagents with platinum(IV) halides. These air-stable, thermally robust materials have since been shown to have the cubane structure in which the platinum atoms attain an 18-electron configuration through triply bridging halogen atoms.