Nucleophilic activation of coordinated carbon monoxide. Part 3. Hydroxide and methoxide reactions with the trinuclear clusters M/sub 3/(CO)/sub 12/ (M = Fe, Ru, or Os): implications with regard to catalysis of the water gas shift reaction

Journal Article · Wed Feb 06 00:00:00 EST 1985 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00289a010· OSTI ID:5677059

Gross, D C; Ford, P C

Reported are quantitative investigations of the reactions of the triangular clusters M/sub 3/(CO)/sub 12/ (M = Fe, Ru, or Os) with methoxide ion in solution. In methanol under a CO atmosphere, both the osmium and ruthenium species form stable 1:1 methoxycarbonyl adducts (M/sub 3/(CO)/sub 12/ + NaOCH/sub 3/ in equilibrium (M/sub 3/(CO)/sub 11/(CO/sub 2/CH/sub 3/))Na); however, for the triiron analogue this adduct undergoes fragmentation to give Fe(CO)/sub 4/(CO/sub 2/CH/sub 3/)/sup -/. Initial adduct formation in each case occurs with an equilibrium constant of about 10/sup 3/ M/sup -1/. In mixed tetrahydrofuran/methanol solutions, K/sub eq/ for Ru/sub 3/(CO)/sub 11/(CO/sub 2/CH/sub 3/)/sup -/ is much larger, an indication of the greater activity of NaOCH/sub 3/ in the less protic solvent. Notably, in such solvent mixtures, the presence of excess methoxide also led to the formation of 2:1 adducts. Rates of adduct formation were examined by using stopped-flow kinetics techniques, and it was shown that in methanol the second-order rate constants (25/sup 0/C) are 11.3 x 10/sup 3/, 2.1 x 10/sup 3/, and 0.6 x 10/sup 3/ M/sup -1/ s/sup -1/ for Fe/sub 3/(CO)/sub 12/, Ru/sub 3/(CO)/sub 12/, and Os/sub 3/(CO)/sub 12/, respectively. Rates were much higher in the mixed THF(tetrahydro-furan)/CH/sub 3/OH solutions; for example, k/sub 1/ (25/sup 0/C) for Ru/sub 3/(CO)/sub 12/ is 2.0 x 10/sup 5/ M/sup -1/ s/sup -1/ in 90/10 THF/CH/sub 3/OH (v/v). Monosubstitution of the ruthenium cluster with (CH/sub 3/O)/sub 3/P markedly reduced the reactivity toward the anionic nucleophile. The reaction of the triruthenium species with hydroxide (Ru/sub 3/(CO)/sub 12/ + OH/sup -/ in equilibrium Ru/sub 3/(CO)/sub 11/(CO/sub 2/H)/sup -/ ..-->.. HRu/sub 3/(CO)/sub 11//sup -/ + CO/sub 2/) was also investigated. Analysis of the reaction kinetics leads to the conclusion that formation of the initial hydroxycarbonyl adduct is somewhat less favorable and is slower than the analogous reaction of methoxide.

• Research Organization: Univ. of California, Santa Barbara
• OSTI ID: 5677059
• Journal Information: J. Am. Chem. Soc.; (United States), Vol. 107:3
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ADDUCTS
DECARBOXYLATION
HYDROGEN PRODUCTION
CATALYSTS
HYDROXIDES
CHEMICAL REACTION KINETICS
IRON COMPOUNDS
METHOXY RADICALS
OSMIUM COMPOUNDS
RUTHENIUM COMPOUNDS
ABSORPTION SPECTROSCOPY
ANIONS
CARBON MONOXIDE
CARBONYLS
CATALYSIS
CHEMICAL ACTIVATION
CHEMICAL REACTION YIELD
COMPARATIVE EVALUATIONS
CORRELATIONS
DATA ANALYSIS
EXPERIMENTAL DATA
INFRARED SPECTRA
LEAST SQUARE FIT
MATHEMATICAL MODELS
METHANOL
MIXED SOLVENTS
REACTION INTERMEDIATES
SODIUM COMPOUNDS
TETRAHYDROFURAN
WATER GAS PROCESSES
ALCOHOLS
ALKALI METAL COMPOUNDS
ALKOXY RADICALS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHARGED PARTICLES
CHEMICAL REACTIONS
DATA
DISPERSIONS
FURANS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
INFORMATION
IONS
KINETICS
MAXIMUM-LIKELIHOOD FIT
MIXTURES
NUMERICAL DATA
NUMERICAL SOLUTION
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
RADICALS
REACTION KINETICS
REFRACTORY METAL COMPOUNDS
SOLVENTS
SPECTRA
SPECTROSCOPY
TRANSITION ELEMENT COMPOUNDS
YIELDS
080104* - Hydrogen- Production- Water Gas Processes
400201 - Chemical & Physicochemical Properties