Thermodynamic studies of competitive adduct formation: single- and double-insertion reactions of carbon monoxide with rhodium octaethylporphyrin dimer
Reactions of carbon monoxide with (octaethylporphyrin)rhodium dimer, ((OEP)Rh)/sub 2/, in toluene produce and equilibrium system involving four species: ((OEP)Rh)/sub 2/ (1), ((OEP)Rh)/sub 2/(CO) (2), (OEP)RhC(O)Rh(OEP) (3), and (OEP)RhC(O)C(C)Rh(OEP) (4). No evidence is found for the formation of a diacarbonyl adduct of 1, which is accounted for on the basis of required structural features of metal-metal-bonded porphyrin dimers. /sup 1/H and /sup 13/C NMR evidence is presented for double insertion of CO into the Rh-Rh bond. NMR methods are used to determine enthalpy and entropy changes for the reaction of 1 with CO to form the following: 2, /Delta/H/sub 2//degree/ = /minus/10/plus minus/ 1 kcal/mol (/minus/41 /plus minus/ 4 kJ/mol), /Delta/S/sub 2//degree/ = /minus/26 /plus minus/ 4 cal/K/center dot/mol/minus/109 /plus minus/ 17 J/K/center dot/mol; 3, /Delta/H/sub 3//degree/ = /minus/12 /plus minus/ 2 kcal/mol (/minus/50 /plus minus/ 8 kJ/mol), /Delta/S/sub 3//degree/ = /minus/31 /plus minus/5 cal/K/center dot/mol (/minus/130 /plus minus/21 J/K/center dot/mol); 4, /Delta/H/sub 8//degree/ = /minus/21 /plus minus/2 kcal/mol (/minus/88 /plus minus/ kJ/mol), /Delta/S/sub 8//degree/ = /minus/62 /plus minus/ 5 cal/K/center dot/mol (/minus/259 /plus minus/ 30 J/K/center dot/mol). Thermodynamic criteria for the double insertion of CO into metal-metal bonds are presented and applied to the (OEP)Rh system.
- Research Organization:
- Univ. of Pennsylvania, Philadelphia (USA)
- OSTI ID:
- 5914172
- Journal Information:
- J. Am. Chem. Soc.; (United States), Vol. 110:18
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CARBON MONOXIDE
CHEMICAL REACTIONS
THERMODYNAMICS
PORPHYRINS
RHODIUM COMPLEXES
ADDUCTS
CARBON 13
CARBONYLS
CATALYSIS
CHEMICAL BONDS
DIMERS
EXPERIMENTAL DATA
HYDROGEN 1
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
THERMODYNAMIC PROPERTIES
TOLUENE
ALKYLATED AROMATICS
AROMATICS
CARBON COMPOUNDS
CARBON ISOTOPES
CARBON OXIDES
CARBOXYLIC ACIDS
CHALCOGENIDES
COMPLEXES
DATA
EVEN-ODD NUCLEI
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
HYDROGEN ISOTOPES
INFORMATION
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RESONANCE
SPECTRA
STABLE ISOTOPES
TRANSITION ELEMENT COMPLEXES
400201* - Chemical & Physicochemical Properties