Metal-catalyzed isomerization complex salts

Ring expansion reactions of the type shown in equations (17) and (18), in which a more equitable distribution of carbon atoms between two rings of a polycyclic hydrocarbon is produced, provide the link between the decyclization reactions above and the annulation reactions considered later. It would seem that the greater the strain in the reactant, the larger the number of potential catalysts. The complexes of seven different metals catalyze the reaction shown in equation (17). Of the possible catalysts, only the silver (I) salts bring about any byproduct formation. The isomerization of [l.l.ljpropellane (equation 18) is catalyzed by [RhCl(PPh3)3]. ... 

Ionic liquids can be used as replacements for many volatile conventional solvents in chemical processes see Table A-14 in the Appendix. Because of their extraordinary properties, room temperature ionic liquids have already found application as solvents for many synthetic and catalytic reactions, for example nucleophilic substitution reactions [899], Diels-Alder cycloaddition reactions [900, 901], Friedel-Crafts alkylation and acylation reactions [902, 903], as well as palladium-catalyzed Heck vinylations of haloarenes [904]. They are also solvents of choice for homogeneous transition metal complex catalyzed hydrogenation, isomerization, and hydroformylation [905], as well as dimerization and oligomerization reactions of alkenes [906, 907]. The ions of liquid salts are often poorly coordinating, which prevents deactivation of the catalysts. 

Many of the significant reactions of unsaturated hydrocarbons (hydrogenation, isomerization, carbonylation, oxidation, polymerization) are catalyzed heterogeneously by metals in or near Group VIII or homogeneously by salts and complexes of these elements. Those reactions effected in both systems are discussed in terms of probable common intermediates anomalies, where they occur, are ascribed either to the ability of surfaces to form intermediate species which cannot be stabilized by single metal atoms or to the ability of the latter to coordinate simultaneously more than one hydrocarbon molecule. 

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