title: Interaction of metal cations with functionalised hydrocarbons in the gas phase: further experimental evidence for solvation of metal ions by the hydrocarbon chain.
abstract: Relative affinity measurements of monovalent metal ions (= Li(+), Cu(+) and Ag(+)) towards aliphatic amines, alcohols and methyl alkanoates (P) have been performed using the kinetic method on the dissociation of metal bound dimer ions of the type P(1)-M(+)-P(2). It was found that the cations' affinity towards long chain (≥C(4) chain length) n- and s-alkylamines, n-alkanols and methyl n- alkanoates was unexpectedly enhanced. This is attributed to a bidentate interaction of the metal ion with the amine, alcohol or ester functional group and the aliphatic chain, paralleling earlier observations on metal bound nitriles. Methyl substitution at the functional group (s-alkylamines compared with n-alkylamines) serves to strengthen only the N•••M(+) bond, and this can be rationalized by the larger proton affinities of s-alkylamines compared to n-alkylamines. This substitution, however, has no effect on the metal ion-hydrocarbon bond. In contrast, methyl substitution remote from the functional group, as in iso-pentylamine, does lead to strengthening of the metal ion-hydrocarbon bond. The cuprous ion affinity of hexadecylamine, C(16)H(33)NH(2) was found to be as large as that for ethylenediamine (352 kJ mol(-1)), known to be a strong copper binding agent. It is argued that such a metal ion-hydrocarbon interaction does not occur in the metal bound dimers.
authors.affiliation: Department of Neurology, Laboratory of Neuro-Oncology, Erasmus Medical Center, The Netherlands. Department of Surgery, Erasmus Medical Center, The Netherlands. n.vanhuizen@erasmusmc.nl.
authors.forename: Nick A
authors.initials: NA
authors.lastname: van Huizen
authors.affiliation: D epartment of Neurology, Laboratory of Neuro-Oncology, Erasmus Medical Center, The Netherlands. t.luider@erasmusmc.nl.
authors.forename: Theo M
authors.initials: TM
authors.lastname: Luider
authors.affiliation: Ontar io Ministry of the Environment and Climate Change, 125 Resources Road, Toronto, Ontario M9P 3V6, Canada. Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S 4M1, Canada. karl.jobst@ontario.ca.
authors.forename: Karl J
authors.initials: KJ
authors.lastname: Jobst
authors.affiliation: Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S 4M1, Canada. terlouwj@mcmaster.ca.
authors.forename: Johan K
authors.initials: JK
authors.lastname: Terlouw
authors.affiliation: C hemistry Department, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N6N5, Canada. johnleonard.holmes@uottawa.ca.
authors.forename: John L
authors.initials: JL
authors.lastname: Holmes
authors.affiliation: D epartment of Neurology, Laboratory of Neuro-Oncology, Erasmus Medical Center, The Netherlands. p.burgers@erasmusmc.nl.
authors.forename: Peter C
authors.initials: PC
authors.lastname: Burgers