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

Journal Article · Sat Jan 01 00:00:00 EST 1994 · Organometallics; (United States)

DOI:https://doi.org/10.1021/om00013a019· OSTI ID:5041760

Cao, S; Reddy, K B; Eyring, E M; Eldik, R van ^[1]

---

1. 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), Vol. 13:1; ISSN 0276-7333
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
REACTION KINETICS
PRESSURE DEPENDENCE
TUNGSTEN COMPLEXES
PHOTOLYSIS
STEREOCHEMISTRY
CHEMICAL ACTIVATION
COMPILED DATA
LIGANDS
PYRIDINES
AZINES
CHEMICAL REACTIONS
COMPLEXES
DATA
DECOMPOSITION
HETEROCYCLIC COMPOUNDS
INFORMATION
KINETICS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
TRANSITION ELEMENT COMPLEXES
400201* - Chemical & Physicochemical Properties
400500 - Photochemistry