Cobalt carbonyl-containing

Iron Carbonyl- and Cobalt Carbonyl-Containing Dendrimers... 

A similar rate expression was first obtained by Natta et al. [19]. The problem with this system, however, is that the yield after 4 h reaction time is only 14 % at 110 °C with Ph, = Pco = 40 MPa and tetrahydrofuran as the solvent[20j. In order to obtain a higher yield, Hidai et al. [20] added a certain amount of Ru3(CO) 2 to the cobalt carbonyl-containing reaction system. Although the hydro-formylation activity of this carbonyl compound is relatively low (cf. Section 2.1.1.2.1), about one-third of that with the cobalt complex, the authors observed a marked increase of the initial reaction rate with increasing ruthenium content. They suggested that the ruthenium species opens an additional route for forming the final C-H bond. Thus, it is to be expected that there is a second reaction rate, 1-2, which can be given by eq. (5) ... 

In a second example, 25.0 mg of a cobalt carbonyl containing 34.4b weight percent cobalt (0.146 mmol Co) was combined with 420 mg lFe(bipy)2J(PF )j. Acetonitrile (5 mL) was added by vacuum transfer. Separation and quantitation as above gave 0.60 mmol of CO evolved, for a CO/Co ratio of 4.10. The empirical formula of the compound is thus determined to be Co(CO) the compound employed was C02 (CO) g. 

EG may also be pioduced via glycolic acid using catalysts containing strong acids (66), cobalt carbonyl (67—69), rhodium oxide (68), or HE solvent (70,71) (see Glycols, ETHYLENE glycol). 

Dendrimers containing metal complexes in the branches. In these compounds (Fig. lc), metal complexes may play the role of connectors along the branches of a dendritic structure as in the case of (tpy)Ru(tpy)2+ (tpy=2,2 6, 2"-ter-pyridine) [6], or may be attached to specific sites as in the case of cobalt carbonyls [7]. 

On irradiation it is converted to the cobalt carbonyl hydride 8, as discussed above. The hydride then reacts with the olefin in a reaction sequence containing only thermal steps /10/. 

The generation of the initial metal-carbon bond in the catalytic cycle by reaction of methyl iodide with a metal carbonyl-containing species has been proposed as a key step in both the cobalt (2) and rhodium (4) catalyzed systems. 

The reaction conditions were mild (room temperature, 1 atm CO) and a two-fold excess of base was used along with a catalytic amount of cobalt carbonyl. The product distribution was quantified by VPC. The mixtures contained starting material, ester product, and various amounts of methyl benzyl ether. No detectable amounts of benzyl alcohol, ketones, or hydrocarbons were seen. Potassium methoxide alone afforded mostly the ether. A mixture of potassium methoxide and alumina gave a slight improvement in ester yield but the predominant product was again the ether. In contrast, when potassium methoxide on alumina was used, the carboxyalkylated product, methyl phenylacetate, was prepared in 70 yield with little ether detected. Benzyl chloride reacted in a similar fashion under these mild reaction conditions. Other alkoxide and carbonate bases could be used as... 

B. Chromium-, Cobalt-, and Iron Carbonyl-Containing Dendrimers.173... 

Methyl benzoate gives88 no carbonyl-containing products over potassium tetrafluoro-cobaltate(III) at 300 °C very low yields of perfluorocyclohexane and perfluorocyclohexene are obtained. 

In the classical oxo process the catalyst cohalt carbonyl is formed in situ by introducing divalent cobalt into the reactor. High temperature is required for this catalyst formation that gives a mixture of aldehydes and alcohols containing only 60-70% of linear product. A new BASF process using cobalt carbonyl hydride shows improved selectivity and efficient catalyst recovery. The catalyst is prepared by passing an aqueous solution of cobalt salt over a promoter and extracting the catalyst from the water phase with olefin. 

Step 4 Decobaltation of the Reaction Product. The product of the hydroformylation reactor containing the catalyst as a mixture of cobalt carbonyl hydride and dicobalt octacarbonyl is fed to the decobaiting section. Mixing the product at 120 °C and 10 atm with a dilute formic acid/ cobalt formate solution in the presence of air decomposes the catalyst (Reaction 9) (12). 

Compared with the analogous hydrogenation of aldehydes, the reaction requires somewhat more drastic conditions (about 200°C and 6 hrs), but the temperature is still within the stability range of the cobalt carbonyl phosphine complexes containing tertiary alkyl phosphines as ligands. If aryl phosphines are used, a more or less pronounced decomposition of the carbonyl complexes can be observed (as indicated by the IR... 

The ammonia or amine photothermally liberated from a cobalt(III) complex can be used to crosslink a carbonyl-containing polymer. One such complex is (120), which can be used in a photoresist composition where the non-crosslinked polymer is dissolved away, leaving a negative image in hardened polymer.246... 

Completely different behavior toward liquid NH3 is shown by the three iron carbonyls Fe(CO)s, Fe3(CO)9, and Fes(CO),2 (98, 99) and the two cobalt carbonyls Co2(CO)8 and Co4(CO)i3 (100). Between -21 and 0°C, Fe(CO)5 and liquid NH3 give a homogeneous, pale-yellow solution from which Fe(CO)5 may be recovered on evaporating off the NH3. The solution contains the carbamoyl complex NHJfOC Fe—CONHJ which cannot be isolated and which is formed by nucleophilic attack of an NH3 molecule on a CO ligand, followed by proton release (101). At 20°C after 14 days of reaction, (NHJ FefCOlJ and CO(NH2)2 are obtained (99) ... 

Pour into an Erlenmeyer containing hexanes (200 mL) and stir for 2 h to decompose the intermediate cobalt-carbonyl complexes. 

Acetylenic molecules are versatile ligands in organometallic chemistry [152— 154]. Examples of acetylene-metal reactions include facile complexations of one triple bond with Co2(CO)s [155-157] and two triple bonds with CpCo(CO)2 (Scheme 31) [158,159]. The hb-PYs contain numerous triple bonds and should be readily metallized through their complexations with the cobalt carbonyls. Upon admixing hb-P20 and the cobalt carbonyls in THF at room temperature, the solution color changed from yellow to brown, accompanied by CO gas evolution. The mixtures remained homogenous towards... 

It has become clear that the carbon-rich hb-PYs are readily curable (from ca. 150 °C), thermally stable (up to ca. 550 °C), and pyrolytically carboniz-able (yield up to 80% at 900 °C). Furthermore, their triple bonds are easily metallizable by the complexations with cobalt carbonyls. Since the polymer complexes contain a large number of metal atoms, we tried to utilize them as precursors for fabrication of metalloceramics. The pyrolyses of the polyyne-cobalt complexes at 1000 °C for 1 h under nitrogen furnished ceramic products 83 and 84 in 50%-65% yields (cf., Scheme 31). All the ceramics were magnetizable and could be readily attracted to a bar magnet. 

Again the ease of reaction depends very much on Q (P, As) and the substituents R1 and R63, 64l The preparation of a compound containing an optically active silicon center, trans-(+)-Pt(Pme2ph)2Cl[Si meph(l-naphthyl)], showed that these complexes are formed with retention of configuration at the silicon96. The stereochemical characteristics are also retained in the syntheses of cobalt carbonyls according to Eq. (9)210 ... 

Paolo Chini began his work in the late 1950s with the characterization of cobalt carbonyl species involved in the hydroformylation of olefins with cobalt catalysts, and in the course of these studies developed improved synthetic methods for the known cobalt carbonyls Co2(CO)8 and Co4(CO)12 [132]. His next steps were the preparation of the heterometallic hydrido complex HFe-Co3(CO)i2 (isoelectronic to Co4(CO)12) and the corresponding anion [FeCo3(CO)12], both a novelty at that time, and of the new hexanuclear cobalt clusters [Co6(CO)15]2, [Co6(CO)14]4, and Co6(CO)16 [133-139]. This work was followed by the synthesis of carbido carbonyl cluster anions [Co6(CO)i4C], [Co6(CO)15C]2 and [Co8(CO)i8C]2, containing an interstitial... 

Recent interest in cobalt films has been driven by the importance of cobalt oxides as cathode materials in hthium batteries. Many different precursors have been employed for the MOCVD growth of cobalt-containing thin films. Diketonate-based precursors include Co(acac)2, Co(tmhd)2, Co(tmhd)3, Co(hfac)2, Co(tmhd)2(tmeda), Co(hfac)2(H20)2, and Co(hfac)2(H20)2 tetraglyme. Carbonyl-based precnrsors (see Carbonyl Complexes of the Transition Metals) inclnde Co2(CO)g, Co(C5H5)(CO)2, various cobalt carbonyl clnsters, Co(CO)3(NO), and Co(CO)2(NO)L (L = PEts, TeMc2, TeEt2). Other cobalt precursors include CoH(P(OnPr)(OMe)2)4, Co(N03)3, and Co(rBu NC(CH3)NtBu)2. ... 

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