Evidence for Alkali Metal Induced Intermolecular Acetylenic Hydrogen Atom Transfer between Hydrogen-Bonded Alkyne Complexes in Solid Argon

Article abstract of DOI:10.1021/j100265a034

Condensation of acetylene, propyne, and 2-butyne/acetylene mixtures with heavy alkali metal atoms (Na, K, Cs) in an argon matrix at 15K has led to the appearance of infrared absorptions due the ethylene, propylene, and trans-2-butene, respectively.These results stand in sharp contrast with the products obtained with lithium.Isotopic studies have shown that ethylene formation involved three different acetylene molecules and evidenced a difference in the product yield with hydrogen vs. deuterium as well as a preference for trans- vs. cis-C2H2D2 formation, which is discussed and rationalized by differences in the zero point energies for the different mixed deuterium isotopes of the intermediate vinyl radical.This trend is amplified by methyl substitution.Spectroscopic evidence was found in these experiments for cesium acetylide (Cs(1+)C2H(1-)) and a cesium-acetylene ? complex, which are involved in the intermolecular acetylenic hydrogen atom transfer process.