Can steric hindrance cause a gradual change in the ring-closure mechanism of complexes of the type W(CO)[sub 5]N-N, where N-N represents a series of substituted bipyridine ligands
- Univ. of Utah, Salt Lake City, UT (United States)
The kinetics of the thermal ring-closure reactions of W(CO)[sub 5]L, produced during the photolysis of W(CO)[sub 6]L, where L = 2,2'-bipyridine, 4,4'-dimethyl-2,2'-bipyridine, 4,4'-diphenyl-2,2'-bipyridine and 4,4'-di-tert-butyl-2,2'-bipyridine, were studied as a function of pressure. The values of the activation parameter [Delta]V* are small and negative for these ligands, supporting an associative interchange mechanism (I[sub a]) for CO extrusion. The [Delta]V* values exhibits a specific trend toward more positive values on increasing the steric hindrance on the ligand. This trend is interpreted as evidence for a gradual change in mechanism from a more associative to a more dissociative ring-closure process. 31 refs., 1 fig., 3 tabs.
- OSTI ID:
- 5041760
- Journal Information:
- Organometallics; (United States), Journal Name: Organometallics; (United States) Vol. 13:1; ISSN 0276-7333; ISSN ORGND7
- Country of Publication:
- United States
- Language:
- English
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400201* -- Chemical & Physicochemical Properties
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AZINES
CHEMICAL ACTIVATION
CHEMICAL REACTIONS
COMPILED DATA
COMPLEXES
DATA
DECOMPOSITION
HETEROCYCLIC COMPOUNDS
INFORMATION
KINETICS
LIGANDS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PRESSURE DEPENDENCE
PYRIDINES
REACTION KINETICS
STEREOCHEMISTRY
TRANSITION ELEMENT COMPLEXES
TUNGSTEN COMPLEXES