Carbonyl complexes of platinum

J. R. Fisher, A. J. Mills, S. Sumner, M. P. Brown, M. A. Thomson, R. J. Ihiddephatt, A. A. Frew, L. Manojovic-Muir, K. W. Muir, Reversible displacement of dihydrogen by carbon monoxide in binuclear platinum complexes. Characterization of binuclear carbonyl complexes of platinum(I), Organometalhcs 1 (1982) 1421-1429. 

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... 

In the early work on the thermolysis of metal complexes for the synthesis of metal nanoparticles, the precursor carbonyl complex of transition metals, e.g., Co2(CO)8, in organic solvent functions as a metal source of nanoparticles and thermally decomposes in the presence of various polymers to afford polymer-protected metal nanoparticles under relatively mild conditions [1-3]. Particle sizes depend on the kind of polymers, ranging from 5 to >100 nm. The particle size distribution sometimes became wide. Other cobalt, iron [4], nickel [5], rhodium, iridium, rutheniuim, osmium, palladium, and platinum nanoparticles stabilized by polymers have been prepared by similar thermolysis procedures. Besides carbonyl complexes, palladium acetate, palladium acetylacetonate, and platinum acetylac-etonate were also used as a precursor complex in organic solvents like methyl-wo-butylketone [6-9]. These results proposed facile preparative method of metal nanoparticles. However, it may be considered that the size-regulated preparation of metal nanoparticles by thermolysis procedure should be conducted under the limited condition. 

My last comment concerns the reaction of palladium olefin complexes with carbon monoxide discovered by Tsuji. I agree that this is most likely to proceed by an insertion rather than an ionic mechanism. Chloride attack on coordinated olefin is rare however. Chloride ion is an inhibitor, for example in the palladous chloride catalyzed hydration of ethylene (0). I, therefore, wondered whether carbon monoxide was affecting the ease with which chloride attacks olefin. One can postulate that carbon monoxide participates in this insertion either as a gas phase reactant or by first forming a carbonyl olefin complex. Such complexes of the noble metals were unknown, but examining the reaction between carbon monoxide and the halogen bridged olefin complexes of platinum revealed that they are formed very readily... 

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... 

It has been suggested (162) that there exists only negligible 7r-backbonding in [AuCl(CO>], and a number of displacement reactions have been described (162, 163). Vibrational and NMR spectroscopic studies have been made of this complex (164), and the results have been compared with those for carbonyl complexes of palladium, platinum, rhodium, and iridium. 

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. 

Carbonatobis(triphenylphosphine)platinum(II) is useful for the preparation of dianionobis(triphenylphosphine)platinum(II) complexes as well as olefin, acetylene and carbonyl derivatives of platinum(0). The method can be used to prepare Pt[P(C6Hs)2CH3] jCCOa) and Pt[As(C6Hs)3] 2(C03). A procedure is available for the preparation of ds-[diacetatobis(diphenylphosphino)pla-tinum] (ds-[Pt(CH3C02)2[P(C6Hs)2l 2]). 

Carbonylation of the isomeric cationic solvated complexes of platinum(II) C and D [the corresponding palladium(II) species react at a much faster rate] proceeds via an alkyl migration mechanism in a study based on NMR detection of the intermediates. This conclusion is in agreement with the available data in the literature kinetic data should, however, complement the information concerning the palladium(II) and plati-num(II) systems. 

Carbonyl complexes of rhodium, ruthenium, osmium, iridium, and platinum, in the presence of H2O and a weak base (e.g., trimethylamine), act as catalysts for the conversion of propene to a mixture of butanol and methylpropanal with the exception of the platinum system, these catalysts are considerably more active than Fe(CO)s as reported by Reppe. Under the same conditions, but in the absence of olefin, the carbonyls act as catalysts for the conversion of CO and H2O to CO2 and H2. The metal carbonyls, together with Fe(CO)s, in the presence of H2O, CO, and a weak base such as McsN, serve as catalysts for the conversion of nitrobenzene, dinitrobenzene, and 2,4- and 2,6-di-nitrotoluene to the corresponding aminobenzene derivatives. 

No reactions of complexes 62 and 63 have been reported. Palladium and platinum form no well-defined dinitrogen complexes. However, until relatively recently there were few carbonyl complexes of palladium and platinum. This has changed rapidly with the preparation of a wide variety of compounds such as dinuclear complexes, e.g., [M2Cl2(ju,-CO)-(ju. -dppm)2] where M = Pd, Pt, and neutral and anionic polynuclear complexes such as [Os2(CO)6 /t-Pt-(CO)(PPh3) 2] and [Pt9(CO)i8]. The absence of simple, mononuclear palladium and platinum dinitrogen complexes should not be construed as evidence that this is a barren area for research. 

There are many carbonyl complexes of nickel, palladium, and platinum containing phosphines (L). Nickel compounds of the type [Ni(CO)4 j,Lj,] are readily formed in substitution reactions of [Ni(CO)4]. Palladium and platinum phosphine carbonyls are prepared by reactions of compounds of these metals with carbon monoxide in the presence of phosphines. The following complexes are known [M(CO)L3], [M3(C0)3L3], [M3(C0)3L4], [Pt(CO)2L2] and [M4(CO)5L4] (M = Pd, Pt). Trinuclear platinum compounds resist oxidation. 

Column structures have also been determined for carbonyl complexes of rhodium, iridium, and platinum. For platinum complexes of the formula [Pt3(CO)6] , the maximum value of n probably does not reach more than 20 (Figure 3.26) and therefore these carbonyls do not show anisotropy of conductivity. Various Ir(I) and Rh(I) complexes possessing column structures are known [IrX(CO)3] (X = C1, Br, I), [IrCl,o7(CO)2.93], [Ir(acac(CO)2], Ho.38lrCl2(CO)2(H20)2.9, Ko.58[IrCl2(CO)2], and... 

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. 

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