Kinetics and mechanism of arene displacement in (eta-arene)dicarbonyl(chalcocarbonyl)chromium(0) complexes, (eta-arene)Cr(CO)/sub 2/(CX) (X = S, Se), by tertiary phosphites
The kinetics and mechanism of the arene substitution reactions of the chalcocarbonyl complexes (eta-arene)Cr(CO)/sub 2/(CX) (X = S, arene = C/sub 6/H/sub 6/, PhMe, PhNMe/sub 2/, PhCO/sub 2/Me, o-C/sub 6/H/sub 4/Me/sub 2/, m-C/sub 6/H/sub 4/(CO/sub 2/Me)Me, p-C/sub 6/H/sub 4/(CO/sub 2/Me)/sub 2/, p-C/sub 6/H/sub 4/(OMe)/sub 2/, 1,3,5-C/sub 6/H/sub 3/Me/sub 3/; X = Se, arene = C/sub 6/H/sub 6/) by tertiary phosphites (L = (MeO)/sub 3/P, (PhO)/sub 3/P, (C/sub 6/H/sub 11/O)/sub 3/P) in methylcyclohexane to form mer-Cr(CO)/sub 2/(CX)L/sub 3/ have been investigated. The reactions are significantly faster than those for the corresponding tricarbonyl complexes and are first-order in both substrate and entering ligand L. Activation parameters for arene = C/sub 6/H/sub 6/ and L = (MeO)/sub 3/P: X = S, ..delta..H/sup double dagger/ = 74.1 kJ mol/sup -1/, ..delta..S/sup double dagger/ = -117 J mol/sup -1/ deg/sup -1/; X = Se, ..delta..H/sup double dagger/ = 74.9 kJ mol/sup -1/, ..delta..S/sup double dagger/ = -100 J mol/sup -1/ deg/sup -1/. A mechanism involving the slight slippage of the arene ring from eta/sup 6/- to eta/sup x/-coordination (6 > x > 4) prior to entry of the first L ligand in the rate-determining step is proposed. The greater reactivity of the thio- and selenocarbonyl derivatives compared to that of the tricarbonyl analogues is attributed to the better ..pi..-acceptor capacities of CS and CSe compared to that of CO, resulting in weaker bonding between the Cr metal and the arene. Also, on the basis of this kinetic study, it appears likely that the thio- and selenocarbonyl complexes will not be as good catalysts as the (eta-arene)chromium tricarbonyl complexes for the hydrogenation of dienes.
- Research Organization:
- McGill Univ., Montreal, Quebec
- OSTI ID:
- 6996753
- Journal Information:
- Inorg. Chem.; (United States), Journal Name: Inorg. Chem.; (United States) Vol. 25:22; ISSN INOCA
- Country of Publication:
- United States
- Language:
- English
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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
AROMATICS
CARBONYLS
CATALYSIS
CATALYSTS
CATALYTIC EFFECTS
CHEMICAL BONDS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHROMIUM COMPLEXES
COMPLEXES
DATA
DIENES
EXPERIMENTAL DATA
HYDROCARBONS
HYDROGEN COMPOUNDS
HYDROGENATION
INFORMATION
INORGANIC ACIDS
KINETICS
LIGANDS
NUMERICAL DATA
ORGANIC COMPOUNDS
PHOSPHOROUS ACID
PHYSICAL PROPERTIES
POLYENES
REACTION KINETICS
SELENIUM COMPLEXES
SULFUR COMPLEXES
THERMODYNAMIC PROPERTIES
THERMODYNAMICS
TRANSITION ELEMENT COMPLEXES