Platinum complexes carbonyl halides

Carbonyl halide complexes of platinum(IV) are less common. The reaction of [Pt(CO)2]s with chloride ion in an aqueous solution of iron(HI) ions gives Pt(CO)H2Cl2, which adds chloride to give Pt(CO)H2ClJ.313,314 Addition of chlorine to a thionyl chloride solution of Pt(CO)2Cl2 at room temperature results in the rapid formation of Pt(CO)Cl (equation 106), which shows a carbonyl stretch at 2191 cm-1. The yellow-orange compound is stable toward Cl- but reacts with water to form C02.315... 

These early successes with carbonyl complexes of rhenium encouraged me to undertake systematic research on the carbon monoxide chemistry of the heavy transition metals at our Munich Institute during the period 1939-45, oriented towards purely scientific objectives. The ideas of W. Manchot, whereby in general only dicarbonyl halides of divalent platinum metals should exist, were soon proved inadequate. In addition to the compounds [Ru(CO)2X2] (70), we were able to prepare, especially from osmium, numerous di- and monohalide complexes with two to four molecules of CO per metal atom (29). From rhodium and iridium (28) we obtained the very stable rhodium(I) complexes [Rh(CO)2X]2, as well as the series Ir(CO)2X2, Ir(CO)3X, [Ir(CO)3]j (see Section VII,A). With this work the characterization of carbonyl halides of most of the transition metals, including those of the copper group, was completed. 

Carbonyl halides of the platinum group metals, however, are often prepared by reacting the metal halide with carbon monoxide. [Ru(CO)3Cl,], and [Rh(CO),Cl], are mentioned above (p. 167). Platinum forms Pt(CO),X, and [Pt(CO)X,],. The latter were the first carbonyl complexes of any element to be described. They were reported by the French chemist, P. Schutzenberger, in 1870. 

The oxidative addition of bromine to a platinum(ii) salt, followed by halide extraction in the presence of CO, leads to the isolation of the platinum(iv) carbonyl complex 19. The authors claim this to be the first example of a structurally... 

An ambiguity in the assignment of mechanism of oxidation of tri-phenylphosphine, catalysed by Pt(PPh8)s, has been resolved, though there remain some details to be settled. The rate of oxidation of carbon monoxide by iron(ni) in the presence of hydrido-carbonyl-halide complexes of platinum(n) is proportional to the concentration of carbon monoxide and proportional to the concentration of platinum(ii) added chloride inhibits the reaction. ... 

Although thesimplecarbonyls of palladium and platinum, e.g., [Pd(CO)4], are not known, the carbonyl halides and some base-substituted compounds have been obtained. The reaction of carbon monoxide with the complexes [PdCl2(o-phen)2] or [PdCl2(dipy)2] in water yields very insoluble products apparently having bridging carbonyl groups 352). While carbonylation of... 

More recently, methods based on the use of mild reductants, able to transfer a single electron to the polyhaloalkyl halide, have been described. Various metals or their derivatives have been employed ruthenium, platinum and their complexes in low oxidation state, iron" and its carbonyl complexes, or tetrakis(triphenylphosphane)palladium. Sodium arcncsul-finate, sodium dithionite" and various oxidants have also been used. Other examples of polyhaloalkyl halide additions to simple alkenes are summarized in Table 1. Typical examples are the formation of diiodide 6, chloro iodide 7, and iodo steroid 8. ... 

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. 

Recent literature describes the synthesis of vinyl esters in the presence of platinum metal complexes. Complexes which have proven particularly suitable in this context are those of ruthenium (eq. (15)), such as, for example, cyclooc-tadienylruthenium halides [36], ruthenium carbonyl complexes, and ruthenium acetate complexes [37]. A characteristic feature of these is their high selectivity with regard to acetylene, so that the production of acetylene polymers is reduced. 

Consistent with low stability for compounds of this type, loss of carbon monoxide has been observed when metal complexes containing two adjacent carbonyl functions have been prepared by an indirect route. For example, a-ketohydrocarbyl complexes of palladium(II) or platinum(II) have been prepared by oxidative addition of the appropriate organic halide to palladium(O) or platinum(O) triphenylphosphine complexes ... 

The syntheses of RhHCPfCsH,),] and RhH(CO)[P(C H5)3]3 described herein are members of a group of preparations each involving addition of a platinum metal halide or halo complex and sources of hydride, carbonyl, and/or nitrosyl ligands to a briskly boiling solution of triphenylphosphine in an alcoholic solvent. ... 

The thermal stability of these compounds increases from iodo carbonyls to chloro compounds, and the resistance to hydrolysis increases in the opposite direction. Reactions of these compounds with HX acids or MX halides give anions of the type [PtX3(CO)] . Such anions are also readily formed by reactions of formic acid with platinum halides or platinum halide complexes. For palladium and platinum, A-frame carbonyls are characteristic (Figure 2.25). ... 

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