Platinum rhodium carbonyl anions

Fig. 12. Infrared spectra of rhodium and platinum polynuclear carbonyl anions in the carbonyl stretching region (tetrasubstituted ammonium or phosphonium salts in THF). MA/NC, ratio of number of metal atoms to the number of negative charges.

Vanhoye and coworkers [402] synthesized aldehydes by using the electrogenerated radical anion of iron pentacarbonyl to reduce iodoethane and benzyl bromide in the presence of carbon monoxide. Esters can be prepared catalytically from alkyl halides and alcohols in the presence of iron pentacarbonyl [403]. Yoshida and coworkers reduced mixtures of organic halides and iron pentacarbonyl and then introduced an electrophile to obtain carbonyl compounds [404] and converted alkyl halides into aldehydes by using iron pentacarbonyl as a catalyst [405,406]. Finally, a review by Torii [407] provides references to additional papers that deal with catalytic processes involving complexes of nickel, cobalt, iron, palladium, rhodium, platinum, chromium, molybdenum, tungsten, manganese, rhenium, tin, lead, zinc, mercury, and titanium. 

Polynuclear anionic metal carbonyl compounds are usually prepared by reduction reactions of metal carbonyls M(CO) with such reducing agents as the alkali metals, NaBH4 in ethers, hydrocarbons, liquid ammonia, and similar solvents [see, for example, reactions (2.54), (2.55), (2.84), (2.89), (2.95>-(2.102), and (2.108)-(2.113)]. In alkali medium the metal carbonyls may be reduced by certain solvents (e.g., alcohols) or by the CO ligand itself, and in the presence of Lewis bases the carbonyls disproportionate to give anionic clusters. The mixed metal clusters containing platinum and rhodium are formed by reduction reactions of chloro complexes... 

The same cluster, [PtRh5(CO)i5], may also be obtained from anionic metal carbonyls of platinum and rhodium ... 

Monomethoxycarbonyl ruthenium complexes have been obtained by reaction of mthenium(O) clusters with methoxide anion in methanol [67]. Hydroxyl-carbonyl complexes of platinum were prepared by nucleophilic attack of OH on a carbonyl ligand [68] or by insertion of CO into a hydroxy platinum complex [69]. Hydroxycarbonyl-bpy complexes of ruthenium [21], iridium and rhodium [21] have been proposed as... 

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