Small Molecule Elimination from Group IVB (Ti, Zr, Hf) Amido Complexes

Description:

This article discusses small molecule elimination from group IVB (Ti, Zr, Hf) amido complexes. An ab initio quantum chemical analysis of HX (X = H, CH₃, Cl, NH₂, SiH₃) elimination by group IVB (Ti, Zr, Hf) amidos (H₂(X)M - NH₂ → H₂M = NH + HX), of interest in the context of CVD precursor design, is reported.

Creator(s):
Creation Date: May 1993
Partner(s):
UNT College of Arts and Sciences
Collection(s):
UNT Scholarly Works
Usage:
Total Uses: 75
Past 30 days: 3
Yesterday: 0
Creator (Author):
Cundari, Thomas R., 1964-

University of North Texas; Memphis State University

Creator (Author):
Gordon, Mark S.

Iowa State University

Publisher Info:
Publisher Name: American Chemical Society
Place of Publication: [Washington, D.C.]
Date(s):
  • Creation: May 1993
Description:

This article discusses small molecule elimination from group IVB (Ti, Zr, Hf) amido complexes. An ab initio quantum chemical analysis of HX (X = H, CH₃, Cl, NH₂, SiH₃) elimination by group IVB (Ti, Zr, Hf) amidos (H₂(X)M - NH₂ → H₂M = NH + HX), of interest in the context of CVD precursor design, is reported.

Degree:
Department: Chemistry
Note:

Reprinted with permission from the Journal of the American Chemical Society. Copyright 1993 American Chemical Society.

Note:

Abstract: An ab initio quantum chemical analysis of HX (X = H, CH₃, Cl, NH₂, SiH₃) elimination by group IVB (Ti, Zr, Hf) amidos (H₂(X)M - NH₂ → H₂M = NH + HX), of interest in the context of CVD precursor design, is reported. Several deductions may be drawn from the calculations. First, in the transition state (TS) for HX elimination, electropositive and electroneutral X give rise to metal-transannular hydrogen (Ht) distances only slightly longer than normal metal-terminal hydride bonds lengths, while electronegative X groups yield substantially longer MHt distances. Second, the HX elimination barrier (∆Hǂelim) is lower when HX is polarized Hδ- • Hδ+ (X = SiH₃) or nonpolar (X = H). Third, a plot of calculated ∆Hǂelim versus MHt distances in the TS. Fourth, analysis of the electronic structure along the intrinsic reaction coordinate (IRC) supports the importance of N-H•••M agostic interactions preceding N-H scission. Fifth, the IRC shows the MHt distance decreasing as Ht is transferred from N to X, reaching a minimum when the transfer is roughly half complete, and then increasing once more is HX is eliminated. These results point to the leaving group (X) playing a crucial role in tuning the bonding the energetics of the TS, and thus the rate of HX elimination. The results lead to the conclusion that materials precursors designed to enhance MHt interaction, through the intermediacy of X, in the TS and along the reaction coordinate will lead to lower activation barriers to XH elimination.

Physical Description:

8 p.

Language(s):
Subject(s):
Keyword(s): amido complexes | transition states | molecules
Source: Journal of the American Chemical Society, 1993, Washington DC: American Chemical Society, pp. 4210-4217
Partner:
UNT College of Arts and Sciences
Collection:
UNT Scholarly Works
Identifier:
  • DOI: 10.1021/ja00063a044 |
  • ARK: ark:/67531/metadc107776
Resource Type: Article
Format: Text
Rights:
Access: Public
Citation:
Publication Title: Journal of the American Chemical Society
Volume: 115
Issue: 10
Page Start: 4210
Page End: 4217
Peer Reviewed: Yes