Synthesis of CH3K in the gas phase: Structural and mechanistic trends for monomeric, unsolvated CH3M and HCCM (M = Li, Na, K)

Douglas B. Grotjahn, T. C. Pesch, M. A. Brewster, L. M. Ziurys

Research output: Contribution to journalArticle

31 Scopus citations

Abstract

Monomeric, solvent-free CH3K has been made in the gas phase and its precise structure determined by millimeter/submillimeter spectroscopy, from which the following parameters were deduced: C-K and C-H bond lengths are 2.633 and 1 135 Å, respectively, and the H-C-H angle is 107.0°. The structure completes a series with those reported for CH3Na and CH3Li, showing the expected decrease in metal-carbon bond length (2.633 to 2.299 to 1.961 Å) ascending the periodic table, but little change in the H-C-H bond angles, which are all near 107°. The latter observation on these simple monomeric species clearly differs from the range of 104.8-108.2°reported for oligomeric CH3M samples in the solid phase, which feature several metal- carbon contacts, showing the importance of measurements on monomeric species. Synthetic details for the methyl compounds and HCCM (M = Li, Na, K) are also discussed. Preparation of HCCLi from HCCBr and Li vapor produced LiBr but possible intermediate radical HCC· was not detected, suggesting synchronous reduction of the C-Br bond. The linear structure of HCCM is contrasted with nonlinear structures of LiCCLi (predicted theoretically), NaCN, and KCN, using Coulombic arguments to explain the different molecular geometries.

Original languageEnglish (US)
Pages (from-to)4735-4741
Number of pages7
JournalJournal of the American Chemical Society
Volume122
Issue number19
DOIs
StatePublished - May 17 2000

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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