Substitution reactions of metal carbonyls

Reagent and catalyst induced substitution reactions of metal carbonyl complexes. M. O. Albers and N. J. Coville, Coord. Chem. Rev., 1984, 53, 227-259 (153). 

Substitution reactions of metal carbonyl compounds. D. A. Brown, Inorg. Chim. Acta, Rev., 1967, 1,35-47 (76). 

Solvent effects on the rate of the decarbonylation of MeCOMn(CO)5 were examined by Calderazzo and Cotton (50) and are presented in part in Table IV. In general they are very small, and no regular trends can be discerned. This virtual lack of dependence of the rate on the nature of the solvent and very little correlation between the rate and the dielectric constant of the solvent are typical of substitution reactions of metal carbonyls (J). In the light of the foregoing, a qualitative observation that CpFe(CO)2-COMe decarbonylates much more readily on treatment at reflux in nonpolar heptane or cyclohexane than in polar dioxane is somewhat intriguing 219). 

Substitution reactions of metal carbonyls frequently indicate differences in bonding characteristics of... 

The work cited in sections 2.4 and 2.5 is representative of the SN1 substitution reactions of metal carbonyls. However, a much more extensive and detailed account has recently been published covering similar reactions of vanadium, chromium, molybdenum, tungsten, rhenium, iron and nickel carbonyls in addition to those of manganese and cobalt2 9a. 

F. Basolo, Mechanisms of Substitution Reactions of Metal Carbonyls , Chem. Br., 1969, 5, 505 and refs, therein. 

With respect to the derivatives of metal carbonyls, the substituted metal carbonyls of the VIB Group (e.g., Mo(CO)apya), the halogenocar-bonyls of iron, ruthenium, iridium, and platinum, the hydridocarbonyls H2Fe(CO)4 and HCo(CO)4 discovered in 1931 and 1934, and the nitrosyl carbonyls FelCOj NOjg and Co(CO)3NO were the most important (/). The known anionic CO complexes were limited to [HFe(CO)J and [Co(CO)J-. For studies of substitution reactions of metal carbonyls at this time, work was almost totally limited to reactions involving the classical N ligands such as NH3, en, py, bipy, and phen. 

Fig. 2.14 Fred Basolo (1920-2007) was the Charles E. and Emma H. Morrison Professor of Chemistry at Northwestern University in Evanston in the US. He worked for his Ph.D. with one of the founders of coordination chemistry in the US, John C. Bailar, and received a doctorate from the University of Illinois in 1943. After working on then-classified projects for the war effort, he joined the chemistry department at Northwestern in 1946, where he was a force to be reckoned with for more than 60 years. Together with Ralph Pearson, he was one of the pioneers in the field of inorganic reaction mechanisms and one of the first studying the kinetics of substitution reactions of metal carbonyls. He coauthored two text books Mechanisms of Inorganic Reactions (with R. G. Pearson) and Coordination Chemistry (with R. C. Johnson). Fred was elected to the National Academy of Science in 1979, was the President of the American Chemical Society in 1983, and received the Priestley Medal, the highest award of the ACS, in 2001 (photo by courtesy from Professor Jim Ibers, Northwestern University)...

The catalytic substitution reactions of metal carbonyl clusters, including [M3(CO)i2] (M = Fe, Ru, or Os), [Ru4H4(CO)i2], [Rh6(CO)i6], and [Co3(CO)9(/it-CCl)], with isocyanides or Group V-donor ligands may be induced by either electrochemical or chemical (benzophenone ketyl) reduction. The most favorable conditions for efficient substitution include (1) the formation of a radical anion with a significant lifetime and (2) the use of a ligand which is not reduced by [Ph2CO], and which is less of a tt acid than CO (166). 

There has been recent interest in the substitution reactions of metal carbonyls. For a generalized reaction involving the replacement of Y in a complex CY by another ligand Z, the overall rate constant is frequently found to be described by... 

There are several recent reviews of the photochemistry of transition metal complexes 3,4,5,29,30,45,466,514,518,580)> the most comprehensive being 4>. However, these papers deal mainly with ionic coordination compounds containing inorganic ligands only one 466> is devoted to photochemical substitution reactions of metal carbonyls and their derivatives, while in another 4> this subject is discussed in a short paragraph. 

Table 5 Photochemical substitution reactions of metal carbonyl compounds Substrate... 

Phosphine and phosphite substitution reactions of metal carbonyls. M = Mn, Fe, Ru... 

Some small changes in rate with changes in the dielectric constant of the solvent have been used to infer the changes in polarity of the reactant complex upon activation. The substitution reactions of metal carbonyl halides show a decrease in rate with increasing dielectric constant, which correlates with an expected decrease in polarity on going to the transition state. On the other hand, the insertion reactions of carbon monoxide into methyl manganese pentacarbonyl show an increase in rate, which suggests a transition state more polar than the reactant. 

In nucleophilic substitution reactions of metal carbonyls it is often difficult to decide whether the nucleophile attacks at the central metal or at a relatively positive site on one of the ligands. Such an example is afforded by reaction of hexamethylborazolechromium tricarbonyl (4)... 

Basolo, F. (1985) Associative substitution reactions of metal carbonyls. Inorg. Chim. Acta, 100, 33. 

A review of substitution reactions of metal carbonyls which are known to be either reagent-prcMuoted or catalyst-induced is particularly timely. The specific use of trimethylamine N-oxlde... 

Turning to carbonyls containing more than one metal atom, Johnson has proposed a new mechanism for the substitution reactions of metal-carbonyl dimers Corraine and Atwood have produced a number of papers dealing with carbonyl anions in reaction with carbonyl dimers. The thermodynamic and kinetic factors that control the reactions are also discussed 2. Heaton et al have discussed the electron-microscopy of transition-metal carbonyl clusters 25,26 Butler et al have published a comparison of photoacousdc, attenuated total reflection, and transmission infrared-spectra of crystalline organoiron(ll) carbonyl-complexes 27. 

The associative substitution reactions of metal carbonyls, and the preparations, bonding and reactivity of thiocarbonyl complexes were also reviewed in 1985. 

A special issue of Inorganics Chimlca Acta commemorating the 100th volume contains reviews on substitution reactions of metal carbonyls known to proceed by associative mechanisms, and on metal carbonyl complexes containing RN=C(R )(R")C=NR or 2-RN=C(R )C H.N ligands. The first review since 1977 of transition metal thiocarbonyls has been published. 

The ability of [Fe2(CO)g(y-SMe)2I to act as a catalyst in substitution reactions of metal carbonyls has been noted. 

In recent years interest has developed in the mechanisms of electrochemically-induced catalytic substitution reactions of metal carbonyls. Darchen, Mahe, and Patin i have shown a general mechanism for redox substitution, depicted as a so-called "square-scheme". Scheme 7.6 ... 

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