Carbonyl complexes of cobalt

Compounds Derived from Alkynes and Carbonyl Complexes of Cobalt, 12, 323... 

Carbonylation of methanol to form acetic acid has been performed industrially using carbonyl complexes of cobalt ( ) or rhodium (2 ) and iodide promoter in the liquid phase. Recently, it has been claimed that nickel carbonyl or other nickel compounds are effective catalysts for the reaction at pressure as low as 30 atm (2/4), For the rhodium catalyst, the conditions are fairly mild (175 C and 28 atm) and the product selectivity is excellent (99% based on methanol). However, the process has the disadvantages that the proven reserves of rhodium are quite limited in both location and quantity and that the reaction medium is highly corrosive. It is highly desirable, therefore, to develop a vapor phase process, which is free from the corrosion problem, utilizing a base metal catalyst. The authors have already reported that nickel on activated carbon exhibits excellent catalytic activity for the carbonylation of... 

Chiral Metal Atoms in Optically Active Organo-Transition-Metal Compounds, 18, 151 13C NMR Chemical Shifts and Coupling Constants of Organometallic Compounds, 12, 135 Compounds Derived from Alkynes and Carbonyl Complexes of Cobalt, 12, 323 Conjugate Addition of Grignard Reagents to Aromatic Systems, I, 221 Coordination of Unsaturated Molecules to Transition Metals, 14, 33 Cyclobutadiene Metal Complexes, 4, 95 Cyclopentadienyl Metal Compounds, 2, 365... 

Many new carbonylic complexes have been obtained from the interaction of alkyne carbonylic complexes of cobalt and iron. Lactonyl complexes form at 70°C under CO pressure of 200 x 10 Nm" (152 x 10 Torr) from hexacarbonylcobalt complexes with alkynes ... 

Upon heating to — 30 "C, metal insertion occurred yielding metallacyclobutenone 5. Similar reactions had earlier been observed with carbonyl complexes of cobalt, iron, and nickel. 

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. 

Most hydroformylation investigations reported since 1960 have involved trialkyl or triarylphosphine complexes of cobalt and, more recently, of rhodium. Infrared studies of phosphine complex catalysts under reaction conditions as well as simple metal carbonyl systems have provided substantial information about the postulated mechanisms. Spectra of a cobalt 1-octene system at 250 atm pressure and 150°C (21) contained absorptions characteristic for the acyl intermediate C8H17COCo(CO)4 (2103 and 2002 cm-1) and Co2(CO)8. The amount of acyl species present under these steady-state conditions increased with a change in the CO/ H2 ratio in the order 3/1 > 1/1 > 1/3. This suggests that for this system under these conditions, hydrogenolysis of the acyl cobalt species is a rate-determining step. 

The introduction of alkyl phosphine complexes of cobalt carbonyl as hydroformylation catalysts was reported to have a significant effect on product composition (50, 51). Slaugh and Mullineaux (52) reported that hexanol with a 91% linear distribution was formed by the hydroformylation of 1-pentene at 150°C, 500 psi, H2/CO 2.0, catalyst [Co2(CO)8 + 2(n-C4H9)3P]. Under the same conditions except at a temperature of 190°C, the n-hexanol was 84% of the hexyl alcohol produced. 

Kinetic studies of the substitution reaction of (CO)3M[ 3-C3(t-Bu)3] (M = Co, Rh, Ir) with P(OEt)3 provide the first examples of dissociative CO substitution for carbonyl complexes of the cobalt triad (equation 256)323. 

The electron impact-induced decomposition pathways of several structurally related /u.-methylene complexes of cobalt, rhodium, manganese, and iron have been elucidated by high resolution measurements, analysis of metastable transition (DADI linked scan), and 2H labeling (46). Terminal carbonyl ligands are generally lost prior to further fragmentation of the three-membered frameworks. Subsequent rearrangement reactions of the... 

Phosphinecarbonyl complexes of cobalt have long been known to act as hydrogenation catalysts. In a recent study involving cyclohexene the kinetics of its hydrogenation by the complex [CoH(CO)2(PBun3)2] were studied. Unlike the systems described above, the carbonyl complexes generally require elevated temperature and pressure. The proposed mechanism is given in Scheme 6. 

A series of cobalt carbonyl complexes of polyphosphazenes have been prepared via arene coordination sites. Examples are shown as 3.65 and 3.66.112 These are synthesized via the reactions of (NPC12) with the sodium salt of the appropriate metal-arene terminated alcohol. Mixed-substituent polymers with trifluoroethoxy or phenoxy cosubstituents have also been prepared. 

In 1980 we published a survey (1) of our major results in this area as of late 1979. These results include extensive work on binuclear CF N PF complexes of cobalt (2,3,4,5) and nickel (6). This paper summarizes our more recent results in this area with particular emphasis on binuclear complexes of chromium, molybdenum, and tungsten as well as some new results on iron carbonyl derivatives. 

In contrast to the chalcogen-bridged complexes, no similar oxygen-bridged compounds of iron, cobalt, or nickel exist. However, we obtained such oxo or i-ol-carbonyl complexes of chromium and its homologs, as well as of rhenium. The compounds are the products of the reactions of the respective metal carbonyls with bases (VII). 

There are marked differences between the carbonyl cations of cobalt and its congeners, rhodium and iridium. For instance, the heavier elements form square-planar carbonyl cations as well as higher coordinate complexes. This is paralleled by the isocyanide cations thus cobalt forms [Co(CNR)5]+ cations (191), whereas rhodium and iridium form [M(CNR)4]+ cations (191, 192, 194). 

The use of Cp rings with pendant phosphines in CpCoL2 complexes has also been reviewed. Carbonyl complexes of this type (Cp Co(CO)2) lose CO at room temperature to afford pendant phosphane adducts (equation 46). The chelated phosphane can then be uncoordinated with ligands such as cod substitution of cod (Section 5.1.4) with alkynes allows the cobalt complex to participate in cychzation reactions (Scheme 26). 

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. ... 

Diiron enneacarbonyl, synthesis 46 Triiron dodecacarbonyl, synthesis 46 Tricarbonyl(cyclooctatetraene)iron, synthesis 47 Iron carbonyl complexes of triphenylphosphine, triphenyl-arsine, and triphenylstibine, synthesis 48 cis-Dinitrobis(ethylenediamine)cobalt(III) nitrite and nitrate, synthesis 60... 

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