Hydrocarbon activation via reversible 1,2-RH-elimination from (tBu3SiNH)3ZrR: Synthetic, structural, and mechanistic investigations

Journal of the American Chemical Society

Volumn 118, Issue 3, 1996, Pages 591-611

  Schaller, Christopher P ^a   Cummins, Christopher C ^a   Wolczanski, Peter T ^a  

^a Department of Population Medicine and Diagnostic Sciences   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0000692882     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja950745i     Document Type: Article

References (155)

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108. cymet > 2.7 kcal/mol at 370 K.
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119. The parabolic representations of the free energy surface arise from the usual ill-defined reaction coordinate that comprises Zr-R and N-H bond-breaking along with C-H and ZrN(π) bond-making and the geometric changes that accompany these events. In this model, the curvature of all 1-R(R′) are considered equivalent (i.e., same dependence on x). While this is not rigorously true, only very minor deviations are expected in this energy region (i.e., the lower portion of each parabola is not consequential). The model also assumes that the reactant to product transition occurs adiabatically, with a facility that is independent of R. For the origin of such models, see: Thornton, E. R. J. Am. Chem. Soc. 1967, 89, 2915-2927. See, also: Hammond, G. S. J. Am. Chem. Soc. 1955, 77, 334-338.
120. The parabolic representations of the free energy surface arise from the usual ill-defined reaction coordinate that comprises Zr-R and N-H bond-breaking along with C-H and ZrN(π) bond-making and the geometric changes that accompany these events. In this model, the curvature of all 1-R(R′) are considered equivalent (i.e., same dependence on x). While this is not rigorously true, only very minor deviations are expected in this energy region (i.e., the lower portion of each parabola is not consequential). The model also assumes that the reactant to product transition occurs adiabatically, with a facility that is independent of R. For the origin of such models, see: Thornton, E. R. J. Am. Chem. Soc. 1967, 89, 2915-2927. See, also: Hammond, G. S. J. Am. Chem. Soc. 1955, 77, 334-338.
121. Cundari, T. R.; Matsunaga, N., submitted for publication.
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124. 1,2-XH-elimination activation entropies are -10(3) eu in three distinct systems: see refs 23, 25 and this work.
125. R′ is a ligand repulsive energy, a correlation coefficient of 0.838 was found for α = 0.036, β = 0.18. and γ = -27.50. The results were consistent with a late transition state that manifests some steric acceleration of 1,2-RH-elimination. Mechanics calculations were performed using BIOGRAF, through an academic collaborators arrangement with Molecular Simulations, Inc. For a related study, see: Brown, T. L. Inorg. Chem. 1992, 31, 1286-1294.
126. R′ is a ligand repulsive energy, a correlation coefficient of 0.838 was found for α = 0.036, β = 0.18. and γ = -27.50. The results were consistent with a late transition state that manifests some steric acceleration of 1,2-RH-elimination. Mechanics calculations were performed using BIOGRAF, through an academic collaborators arrangement with Molecular Simulations, Inc. For a related study, see: Brown, T. L. Inorg. Chem. 1992, 31, 1286-1294.
127. clim (1-R) vlaues, possibly because the steric factors are of minor consequence in these reactions. (a) More O'Ferrall, R. A. J. Chem. Soc. B. 1970, 274-277. (b) Jencks, W. P. Chem. Rev. 1972, 72, 705-718.
128. clim (1-R) vlaues, possibly because the steric factors are of minor consequence in these reactions. (a) More O'Ferrall, R. A. J. Chem. Soc. B. 1970, 274-277. (b) Jencks, W. P. Chem. Rev. 1972, 72, 705-718.
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130. Current values have been compiled by John E. Bartmess, Department of Chemistry, University of Tennessee, Knoxville, TN 37996.
131. Current values were obtained from Andrew Streitweiser, Jr., Department of Chemistry, University of California, Berkeley, Berkeley, California, 94720. See, also: Streitweiser, A., Jr.; Juaristi, E.; Nebenzahl, L. L. In Comprehensive Carbanion Chemistry, Part A; Buncel, E., Durst, T., Eds.; Elsevier: Amsterdam, 1980.
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144. c < -8.6 kcal/mol.
145. For related ab initio calculations probing methane activations of a different type, see: (a) Schreiner, P. R.; von Ragué Schleyer, Schaefer III, H. F. J. Am. Chem. Soc. 1993, 115, 9659-9666. (b) Olah, G A.; Hartz, N.; Rasul, G.; Surya Prakash, G. K. J. Am. Chem. Soc. 1995, 117, 1336-1343.
146. For related ab initio calculations probing methane activations of a different type, see: (a) Schreiner, P. R.; von Ragué Schleyer, Schaefer III, H. F. J. Am. Chem. Soc. 1993, 115, 9659-9666. (b) Olah, G A.; Hartz, N.; Rasul, G.; Surya Prakash, G. K. J. Am. Chem. Soc. 1995, 117, 1336-1343.
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152. 1H} NMR spectra of selected derivatives are included in the supporting information for ref 21.
153. Solubility Data Series: Kertes, A. S., Ed.; Pergamon Press, London; Vol. 27/28 (Methane).
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155. o).