Metal carbonyl anions halides

It has been noted (Section II,B,1) that reactions between transition metal carbonyl anions and silicon halides often fail to produce species containing silicon-transition metal bonds, and that such failure has been ascribed to nucleophilic attack by carbonyl oxygen. It is therefore interesting that compounds containing Si—O—C—transition metal linkages have recently been isolated from such reactions [Eqs. (105) (R = Me, Ph) 183) and (106)... 

Thallium(i) salts have long been used in reactions with organic and organometallic halide complexes as a means of activating the halide by removal as insoluble T1X. However, the thallium ions proved not to be innocent bystanders, and numerous examples were reported in COMC (1995) where the metal-bound thallium complexes were formed. Deliberate reactions of thallium(i) and thallium(m) salts with metal carbonyl anions have yielded a variety of complexes of the form T1 MLJ3. In the past decade, new examples of metal carbonyl derivatives of thallium have been prepared (see Table 2). In addition, the propensity for Tl+ to form adducts with 16-electron noble metal complexes has been exploited. 

A recent report( ) on the use of iron carbonyl and potassium carbonate in a similar carboxyalkylation scheme to prepare methyl phenylacetate prompted us to examine the use of carbonate on alumina in a similar manner. It was suggested that if the amount of free base was less than the amount of iron carbonyl than ether formation would not occur being that iron carbonyl was a better electrophile than benzyl halide. Under our conditions, the metal carbonyl anion... 

Metal carbonyl anions react with main group halides and oxides to yield a number of main-group transition-metal carbonyl complexes in good yields. These complexes serve as starting materials for a number of higher nuclearity cluster complexes. 

In the organometallic field the reaction of R3Sn ions (R = CH3, Ph) with aromatic and aliphatic substrates has been reported. Another example is the substitution of aryl or vinyl halides by iron(I) porphyrins under electrochemical induction43, and the electrochemical arylation of metal carbonyl anions to form C5H5(CO)3M—cr—Ar (M = W, Mo Ar = Ph, C6H4N02)4b. 

Bismuth readily forms bonds to many metals. The most direct route to transition metal - bismuth complexes is the reaction of metal-carbonyl anions with bismuth halides. The complexes Bi Mn(CO)5 3, Bi CpMo(CO)3 3, Bi Fe(CO)2Cp 3, Bi Co(CO)4 3, Bi Ru(CO)2Cp 3, and Bi Ni(CO)C5Mes 3 (Scheme 2, (24)) are obtained by this method. 

In addition to displacement of halides, ligands can also be displaced by metal carbonyl anions, as shown in equation (45). These reactions need not be restricted to formation of dimers. Incorporation of the anions into existing polymetahic complexes has proven to be a general means of expanding the cluster size. 

The primary method of synthesis of heterobimetallic complexes may involve electron transfer between metal halides and metal-carbonyl anions " ... 

The electron-transfer reactions of metal-carbonyl anions have been reviewed. Metal-carbonyl anions exhibit one-and two-electron reactions. The two-electron processes involving transfer of groups such as hydrogen, alkyl, and halogen between metal centers are related to the nucleophilicity of the anion involved. The one-electron processes are primarily outer-sphere electron transfers. However, in contrast to organic reactions, the metal-carbonyl anions can also undergo inner-sphere electron transfers. This is usually the case when an anion of low nucleophilicity transfers an electron to a metal-carbonyl cation or halide. 

Although a variety of new preparative routes has been developed in recent years (for reviews see refs 1 -10), the transformation of the metal-carbonyl carbon bond of a metal-carbonyl complex into a metal-carbene carbon bond is still the most useful and versatile method for preparing transition-metal carbene complexes. The addition of a carbanion to the carbon atom of a carbonyl ligand yields an anionic acyl complex that subsequently can be reacted with an electrophile to give a neutral carbene complex. Thus, the syntheses of anionic acyl and neutral carbene complexes are closely related, for almost all the carbene complexes considered in this section acyl complexes are precursors, although most have not been isolated and characterized. The syntheses of acyl complexes via CO insertion (for reviews see refs. 11, 12) or by reaction of metal carbonyl anions with acyl halides is outside the scope of this section. 

Reactions of metal carbonyl anions with 1,1- or 1,2-dihaloalkanes also do not yield an alkyl metal product, owing to rapid 1,1- or 1,2-M—X elimination e.g., the reaction of Na[Mn(CO)5] and 1,2-dibromoethane produces MnBrfCO), and C2H4, rather than Mn(CH2CHjBr)(CO)5 or (OC)5MnCH2CH2Mn(CO)s. Reactions of metal carbonyl anions with perfluoroalkyl halides produce metal carbonyl halides, rather than perfluoro-alkyl-metal species. This is because of the reverse polarity of the C—X bond . 

The intermediate metal hydride has been isolated on occasion for Co and Mn , and Eq. (b) has actually been used to prepare silicon-metal bonds (see 5.2.3.2.2.). Inspection of Table 1 reveals the ease of reaction of Co2(CO)g compared with the other carbonyls. Normally this reaction is performed simply by condensing volatile silane onto the carbonyl in the absence of solvent and then allowing rapid reaction in the liquid phase at room temperature, but for the remaining carbonyls it is necessary to use elevated temperatures and sealed, evacuated tubes. The products are volatile and readily purified by vacuum fractionation or sublimation, but are often oxygen and moisture sensitive. The route is most efficient for RjSi derivatives of Co, Mn and Re, which are not generally obtainable by the reactions of silicon halides with metal carbonyl anions (see S.8.3.3.I.). In this way lCo(SiR,)(CO -] = Et, Phj, Clj -, (OEt)j, F/, ... 

Reaction of a metal carbonyl anion with alkyl halide. 

Oxidative Addition. C and Q are both greater in the product than in the starting material. Reactions of metal carbonyl anions with organic halides to form cr-bonded alkyl derivatives fall into this category. Thus, the Mn(CO)5 anion (C = 5, Q = —1) reacts with methyl iodide to form CH3Mn(CO)5 (C = 6, Q = 0) according to the following equation ... 

In 1960 several groups of workers developed a route to the parent complex, TT-allylcobalt tricarbonyl (VII) 122, 123, 170) and also to tt-allylmanganese tetracarbonyl (VIII) 14S, 170). These syntheses were based on reactions of appropriate metal carbonyl anions with allyl halides as shown below. 

The most direct and successful synthesis of metal propargyl complexes involves nucleophilic attack of a metal carbonylate anion at a propargyl halide (9a-c,IO) [Eqs. (1) and (2)]. The propargylic products isolated... 

A related biphasic synthesis uses [Co(CO)4] as the catalyst, but in this case the reaction is limited to substrates such as benzyl and naphthylmethyl halides which are susceptible to attack by the metal carbonyl anion. ... 

Between Different Metals in Carbonyls and Their Derivatives 9.2.5.4. By Reactions of a Metal Halide with a Metal Carbonyl Anion... 

Displacement of a metal-coordinated halide by a metal carbonyl anion is a good method for forming a bond between the two metals. This method is related to redox condensation, differing only in having the halide as leaving group, instead of carbon monoxide. 

Metal elusters are synthesized by this method. Either mononuclear metal carbonyl anions or polynuclear metal carbonyl anions with metal halides may be used ... 

Reaction of metal carbonyl anion with acyl halide. 

Other alkenyl complexes have been formed by displacement of fluoride or chloride ion from fluoro-olefins by metal carbonyl anions, by reactions of the perfluoroalkenylsilver derivative with metal halide compounds, and by insertion of an alkyne into a metal-X bond, and parameters are given with structures [168] to [187]. (8, 86-91) As... 

The carbonylation of a benzyl halide in the presence of iron pentacarbonyl to give a phenylacetic acid may serve to exemplify the interaction of a metal carbonyl, carbon monoxide, PT catalyst, aqueous sodium hydroxide, and the substrate [79]. Fe(CO)5 is attacked by QOH at the interphase, and the species formed is extracted into the depths of the oganic phase, where it reacts with CO and benzyl halide (Eqs. 13 and 14). This new anion 3 is the actual catalyst. It reacts with a second benzyl halide to give a non-ionic intermediate 4 (Eq. 15). By insertion of CO and attack of QOH, 4 is decomposed to the reaction product under regeneration of 3 (Eq. 16). Thus, the action of the PT catalyst is twofold. Firstly it transports the metal carbonyl anion. More important seems to be its involvement in the (rate-determining) decomposition step. A basically similar mechanism was proposed for cobalt carbonyl reactions [80], which have been modified somewhat quite recently (see below). 

Chemiluminescence and photoluminescence in diatomic iron oxide, Rb2, and alkali-metal dimers with halogen atoms and metal vapour-oxidant flames,202 203 lifetime measurements of selectively excited states of diatomic hydrides,204 photodissociation of alkali-metal halide vapours,206 spin-orbit relaxation of the HTe ( 2IIi) radical,20 the photodecomposition of metal carbonyl anions such as [Mn(C04)] in the vapour phase,207 and the fluorescence of Rhodamine 6G in the vapour phase 208 have been studied in recent reports. In the last study it was concluded that an insufficient concentration of the fluorescing dye could be maintained in the vapour phase to permit laser action to occur. 

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