title: Molecular salt effects in the gas phase: tuning the kinetic basicity of [HCCLiCl]⁻ and [HCCMgCl₂]⁻ by LiCl and MgCl₂.
abstract: A combination of gas-phase ion-molecule reaction experiments and theoretical kinetic modeling is used to examine how a salt can influence the kinetic basicity of organometallates reacting with water. [HC≡CLiCl](-) reacts with water more rapidly than [HC≡CMgCl2](-), consistent with the higher reactivity of organolithium versus organomagnesium reagents. Addition of LiCl to [HC≡CLiCl](-) or [HC≡CMgCl2](-) enhances their reactivity towards water by a factor of about 2, while addition of MgCl2 to [HC≡CMgCl2](-) enhances its reactivity by a factor of about 4. Ab initio calculations coupled with master equation/RRKM theory kinetic modeling show that these reactions proceed via a mechanism involving formation of a water adduct followed by rearrangement, proton transfer, and acetylene elimination as either discrete or concerted steps. Both the energy and entropy requirements for these elementary steps need to be considered in order to explain the observed kinetics.
authors: School of Chemistry and Bio21 Institute, University of Melbourne, Melbourne, Victoria 3010 (Australia); ARC Centre of Excellence for Free-Radical Chemistry and Biotechnology. gkhai@unimelb.edu.au.
authors: George N
authors: GN
authors: Khairallah
authors: Gabriel
authors: G
authors: da Silva
authors: Richard A J
authors: RA
authors: O'Hair
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D005740:Gases / Q000737:chemistry*; D007700:Kinetics; D018021:Lithium Chloride / Q000737:chemistry*; D015636:Magnesium Chloride / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
chemical_list: D000480:Alkynes; D005740:Gases; D015636:Magnesium Chloride; D014867:Water; D018021:Lithium Chloride
keywords: ab initio calculations; gas-phase reactions; mass spectrometry; organometallic compounds; salt effect