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Title: Intramolecular coupling of eta/sup 2/-iminoacyl groups at group 4 metal centers: a kinetic study of the carbon-carbon double-bond-forming reaction

Abstract

The series of bis(eta/sup 2/-iminoacyl) compounds of general formula M(OAr)/sub 2/(eta/sup 2/-R'NCR)/sub 2/ (M = Ti, Zr, Hf; OAr = 2,6-diisopropyl- and 2,6-di-tert-butylphenoxide; R = CH/sub 3/, CH/sub 2/Ph; R' = various substituted phenyls) undergo intramolecular coupling on thermolysis to produce the corresponding enediamide derivatives M(OAr)/sub 2/(R'NC(R) = C(R)NR'). A kinetic study of the reaction in hydrocarbon solvents has shown it to be first order. The reaction is metal dependent with the rate decreasing in the order Ti > Zr > Hf. The rate of the reaction is also dependent on the steric and electronic nature of the nitrogen substituent (R'). The use of the bulky aryl group 2,6-dimethylphenyl retards the reaction, while the use of various 3- and 4-substituted phenyls (3-F, 3-OMe, 4-OMe, 4-Cl, 4-NMe/sub 2/) shows the reaction to be accelerated by electron-withdrawing substituents. A sigma plot based on kinetic data obtained at 67/sup 0/C and 77/sup 0/C yielded rho values of 0.83 (R = 0.97) and 0.84 (R = 0.95), respectively. Both the steric and electronic dependence of the reactivity on the nitrogen substituents is discussed mechanistically and used to rationalize the much more facile intramolecular coupling observed for the related eta/sup 2/-acyl (eta/sup 2/-OCR) functionalities.

Authors:
; ;
Publication Date:
Research Org.:
Purdue Univ., West Lafayette, IN (USA)
OSTI Identifier:
7247375
DOE Contract Number:  
FG22-85PC80909
Resource Type:
Journal Article
Journal Name:
J. Am. Chem. Soc.; (United States)
Additional Journal Information:
Journal Volume: 110:5
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; HAFNIUM COMPOUNDS; CHEMICAL REACTIONS; ORGANIC NITROGEN COMPOUNDS; ORGANOMETALLIC COMPOUNDS; TITANIUM COMPOUNDS; ZIRCONIUM COMPOUNDS; ADDUCTS; BINDING ENERGY; CHEMICAL REACTION KINETICS; EXPERIMENTAL DATA; MEDIUM TEMPERATURE; DATA; ENERGY; INFORMATION; KINETICS; NUMERICAL DATA; ORGANIC COMPOUNDS; REACTION KINETICS; REFRACTORY METAL COMPOUNDS; TRANSITION ELEMENT COMPOUNDS; 400201* - Chemical & Physicochemical Properties

Citation Formats

Durfee, L D, McMullen, A K, and Rothwell, I P. Intramolecular coupling of eta/sup 2/-iminoacyl groups at group 4 metal centers: a kinetic study of the carbon-carbon double-bond-forming reaction. United States: N. p., 1988. Web. doi:10.1021/ja00213a017.
Durfee, L D, McMullen, A K, & Rothwell, I P. Intramolecular coupling of eta/sup 2/-iminoacyl groups at group 4 metal centers: a kinetic study of the carbon-carbon double-bond-forming reaction. United States. https://doi.org/10.1021/ja00213a017
Durfee, L D, McMullen, A K, and Rothwell, I P. 1988. "Intramolecular coupling of eta/sup 2/-iminoacyl groups at group 4 metal centers: a kinetic study of the carbon-carbon double-bond-forming reaction". United States. https://doi.org/10.1021/ja00213a017.
@article{osti_7247375,
title = {Intramolecular coupling of eta/sup 2/-iminoacyl groups at group 4 metal centers: a kinetic study of the carbon-carbon double-bond-forming reaction},
author = {Durfee, L D and McMullen, A K and Rothwell, I P},
abstractNote = {The series of bis(eta/sup 2/-iminoacyl) compounds of general formula M(OAr)/sub 2/(eta/sup 2/-R'NCR)/sub 2/ (M = Ti, Zr, Hf; OAr = 2,6-diisopropyl- and 2,6-di-tert-butylphenoxide; R = CH/sub 3/, CH/sub 2/Ph; R' = various substituted phenyls) undergo intramolecular coupling on thermolysis to produce the corresponding enediamide derivatives M(OAr)/sub 2/(R'NC(R) = C(R)NR'). A kinetic study of the reaction in hydrocarbon solvents has shown it to be first order. The reaction is metal dependent with the rate decreasing in the order Ti > Zr > Hf. The rate of the reaction is also dependent on the steric and electronic nature of the nitrogen substituent (R'). The use of the bulky aryl group 2,6-dimethylphenyl retards the reaction, while the use of various 3- and 4-substituted phenyls (3-F, 3-OMe, 4-OMe, 4-Cl, 4-NMe/sub 2/) shows the reaction to be accelerated by electron-withdrawing substituents. A sigma plot based on kinetic data obtained at 67/sup 0/C and 77/sup 0/C yielded rho values of 0.83 (R = 0.97) and 0.84 (R = 0.95), respectively. Both the steric and electronic dependence of the reactivity on the nitrogen substituents is discussed mechanistically and used to rationalize the much more facile intramolecular coupling observed for the related eta/sup 2/-acyl (eta/sup 2/-OCR) functionalities.},
doi = {10.1021/ja00213a017},
url = {https://www.osti.gov/biblio/7247375}, journal = {J. Am. Chem. Soc.; (United States)},
number = ,
volume = 110:5,
place = {United States},
year = {Wed Mar 02 00:00:00 EST 1988},
month = {Wed Mar 02 00:00:00 EST 1988}
}