Methane Activation by Group IVB Imido Complexes

Description:

Article discussing an ab initio study of methane activation by group IVB imido complexes.

Creator(s): Cundari, Thomas R., 1964-
Creation Date: 1992  
Partner(s):
UNT College of Arts and Sciences
Collection(s):
UNT Scholarly Works
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Creator (Author):
Cundari, Thomas R., 1964-

University of North Texas; Memphis State University

Publisher Info:
Publisher Name: American Chemical Society
Place of Publication: [Washington, DC]
Date(s):
  • Creation: 1992
Description:

Article discussing an ab initio study of methane activation by group IVB imido complexes.

Degree:
Department: Chemistry
Note:

Reprinted with permission from the Journal of the American Chemical Society. Copyright 1992 American Chemical Society.

Note:

Abstract: An ab initio study of methane activation by group IVB imido complexes, when coupled with available experimental data, reveals an interesting picture of this important reaction. Initial interaction of methane and (H)₂M=NH leads to the formation of alkane complexes bound by ≈9 kcal mol⁻¹. Experiment indicates that the polarity of the metal-ligand bond upon which the C-H is activated plays an important role in facilitating subsequent scission. Calculations support this hypothesis and suggest that formation of the alkane complex acts to increase Cδ-Hδ polarization, setting the stage for C-H cleavage. Calculated methane elimination barriers for (H)₂M(CH₃)(NH₂) (M=Ti, Zr, Hf) are in good agreement with experimental models in terms of absolute numbers and trends as a function of metal. Calculated methane activation barriers follow the order Ti > Zr > Hf, in line with calculated exothermicities. Calculated geometries indicate a late transition state for methane elimination, in agreement with experimentally determined activation parameters. The TSs have a kite-shaped geometry with an obtuse angle about the H of the C-H bond being activated (Ht) and a short MHt distance, 1-2% greater than normal. The short MHt distance suggests a stabilizing interaction, supported by a positive bond overlap population. Calculation of the intrinsic reaction coordinate demonstrates the importance of agostic interactions between N-H and M along the reaction coordinate.

Physical Description:

7 p.

Language(s):
Subject(s):
Keyword(s): methane | alkane complexes
Source: Journal of the American Chemical Society, 1992, Washington DC: American Chemical Society, pp. 10557-10563
Partner:
UNT College of Arts and Sciences
Collection:
UNT Scholarly Works
Identifier:
  • DOI: 10.1021/ja00052a060
  • ARK: ark:/67531/metadc107807
Resource Type: Article
Format: Text
Rights:
Access: Public
Citation:
Publication Title: Journal of the American Chemical Society
Volume: 114
Issue: 26
Page Start: 10557
Page End: 10563
Peer Reviewed: Yes