Fundamental metal carbonyl equilibria, V 1Reference [29][b] should be considered as Part IV; for Part III see reference [1]. 1 :

Tannenbaum, Rina; Dietler, Urs K.; Bor, G.; Ungváry, Ferenc

doi:10.1016/s0022-328x(98)00798-0

Cited by 29 publications

(16 citation statements)

References 41 publications

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“…Previously we have noted that our K p ‘ values that were measured for the hydrogenation of Co 2 (CO) 8 in supercritical carbon dioxide 5 were very close to those previously measured in solution phase by Ungvary . Recently, a new set of solution-phase data has become available, and it was noted in that study that the K p ‘ data from all of the sources were sufficiently consistent that all of it could be combined and fit with a single linear regression . The small solvent effect for Co 2 (CO) 6 ( n -Bu 3 P) 2 in Table suggests that this will likely be a good approximation for the Co 2 (CO) 6 L 2 complexes as well.…”

Section: Discussionsupporting

confidence: 82%

“…The Co−Co bond energy is linked to the Co−H bond energy by the enthalpy change for the hydrogenation of the dimer. This latter quantity has been investigated independently by three groups with excellent agreement. ,, (See ref for a discussion of a fourth observation that is inconsistent with the other three.) Accordingly, if the Co−H bond energy is 8 kcal/mol higher, then the Co−Co bond energy must be 16 kcal/mol higher, placing it at 35 kcal/mol.…”

Section: Referencesmentioning

confidence: 95%

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Effect of Phosphines on the Thermodynamics of the Cobalt-Catalyzed Hydroformylation System

et al. 2006

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Thermodynamic parameters relevant to the phosphine-modified cobalt hydroformylation reaction are reported. Equilibrium constants for the hydrogenation of Co 2 (CO) 6 L 2 to yield HCo(CO) 3 L were determined using in situ 1 H and 31 P NMR spectroscopy between 75 and 175 °C for various solvents and phosphine ligands. Special emphasis was placed on n-Bu 3 P, as this ligand is prototypical of the Shell hydroformylation process. The resultant van't Hoff plots yield the enthalpy and entropy change (∆H ) 7.0 ( 0.4 kcal/mol and ∆S ) 2 ( 1 cal/mol•K) for the case of L ) n-Bu 3 P in benzene solvent. These parameters were found to be relatively insensitive to changes in the solvent, suggesting that the hydride product is not very polar. Even for isobutyl alcohol solvent, the resultant enthalpy and entropy changes (∆H ) 5.8 ( 0.4 kcal/mol and ∆S ) -2 ( 1 cal/mol•K) were found to be similar to those obtained in benzene and dioxane. Analysis of the 31 P NMR line widths allows rigorous lower limits to be established for the catalytically relevant Co-Co and Co-H bond energies in the case of L ) n-Bu 3 P (Co-Co g 23 kcal/mol and Co-H g 60 kcal/mol) relative to the previously reported values for the case of L ) CO (Co-Co ) 19 ( 2 kcal/mol and Co-H ) 59 ( 1 kcal/mol).

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Section: Discussionsupporting

confidence: 82%

Section: Referencesmentioning

confidence: 95%

Effect of Phosphines on the Thermodynamics of the Cobalt-Catalyzed Hydroformylation System

et al. 2006

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“…The carbon monoxide partial pressure was 0.59 atm. The reaction was carried out at 43 • C. A sampling tube reaching the bottom of the reaction autoclave was connected directly to a flow-through high pressure-high temperature infrared cell [15,16]. Before each spectrum was scanned, the cell was flushed with 10-15 ml of fresh solution from the autoclave by opening a discharge valve placed after the cell.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…This breakdown of the equilibrium can be achieved only if the olefin reacts directly with one of the cobalt carbonyl species involved in one of the above equilibrium reactions. We must rule out the hypothesis that a shift in the equilibrium occurs due to a change in the nature of the solvent caused by the addition of the olefin, since the olefin represents only 4% of the solvent, and studies of the reaction between Co 2 (CO) 8 and hydrogen in benzene [22,23] gave similar results to studies of the same reaction carried out in saturated hydrocarbons [15,22]. We propose, therefore, that the following reaction occurs upon introduction of the olefin:…”

Section: Proposed New Alternative Mechanismmentioning

confidence: 97%

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Re-evaluation of the mechanism of the stoichiometric hydroformylation of olefins with cobalt carbonyls as catalysts

Tannenbaum¹,

Bor²

2004

Journal of Molecular Catalysis A: Chemical

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Carbonyl Complexes of the Transition Metals

Calderazzo¹

2005

Encyclopedia of Inorganic Chemistry

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Carbon monoxide is a versatile ligand as it forms compounds with both transition metals and main group elements. Transition d metals of electronic configuration d n (0 < n < 10) form the most numerous class of these compounds, although recent progress has been made in expanding the area of existence toward main group, lanthanide (4f) and actinide (5f) metals. The most extensively studied series of carbonyl derivatives have the general formula [M(CO) n ] m , with n representing the coordination number of the central metal atom M, and m being the nuclearity of the system. In these compounds, the central metal atom is in the zero oxidation state. Starting from readily available inorganic derivatives in a positive oxidation state, the synthesis of these compounds normally requires a reducing agent capable of acting in the presence of carbon monoxide: in fact, only nickel metal, as a finely divided activated powder, is reactive toward CO leading to the corresponding derivative Ni(CO) 4 . The selection of the reducing agent varies as a function of the position of the metal M within the periodic table. There is a general trend of an increase in the nuclearity m toward the end of the transition d series, the nuclearity being related to the bonding arrangements of the CO ligand, which may act as terminal, doubly bridging or triply bridging. Metal carbonyls are characterized by IR‐active vibrations around 2000 cm −1 associated with the carbonyl groups. Vibrational spectra in solution give important information about: (a) the electronic distribution within the M–CO bond in terminally bonded carbonyl groups; (b) the molecular structure associated with the number of bands observed; (c) the type of bonding in dinuclear or polynuclear compounds. X‐ray diffraction data have been extensively used in order to define the molecular structure in the solid state. The metal–CO combinations span a wide range of oxidation states, derivatives being known for oxidation states from +III to −IV. Metal carbonyls undergo three types of reaction: (a) substitution of the carbonyl groups, whereby the oxidation state of the central metal atom remains unchanged, (b) oxidation, and (c) reduction. Carbonyl derivatives of early‐ and late transition metals present specific bonding and spectroscopic properties. Concerning the transition elements of groups 6–9, the M–CO bond dissociation enthalpy increases down the group, and is normally greater than the metal–metal bond enthalpy, the latter being estimated from the heat of atomization. From a mechanistic viewpoint, substitution and redox reactions have been studied extensively. A special case of substitution is the migratory carbonyl insertion, by which an M–R bond to a carbyl group R is converted by CO into the M–(CO)R sequence.

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Fundamental metal carbonyl equilibria, V 1Reference [29][b] should be considered as Part IV; for Part III see reference [1]. 1 :

Cited by 29 publications

References 41 publications

Effect of Phosphines on the Thermodynamics of the Cobalt-Catalyzed Hydroformylation System

Effect of Phosphines on the Thermodynamics of the Cobalt-Catalyzed Hydroformylation System

Re-evaluation of the mechanism of the stoichiometric hydroformylation of olefins with cobalt carbonyls as catalysts

Carbonyl Complexes of the Transition Metals

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