title: Mass spectrometric study of some protonated and lithiated 2,5-disubstituted-1,3,4-oxadiazoles.
abstract: The mass spectrometric behavior of lithiated derivatives of 2,5-disubstituted-1,3,4-oxadiazoles has confirmed the skeletal rearrangement presented earlier for protonated derivatives. In the case of [M + H](+) ions the loss of isocyanic acid was observed and for [M + Li](+) ions the loss of lithium isocyanate occurred. On the other hand, benzoyl ions [RCO](+) were formed from [M + H](+) ions, but not from [M + Li](+) ions. Formation of benzoyl ions was in agreement with the differences between bond orders calculated for [M + H](+) ions and neutral molecules. From [M + Li](+) ions the [RCNLi](+) fragment ions were formed, but the formation of [RCNH](+) fragment ions from [M + H](+) ions was not observed. This result can be explained on the basis of theoretically calculated stabilities of these fragment ions, since the calculated heats of formation of [RCNLi](+) ions were found to be substantially lower than those of the respective [RCNH](+) ions.
authors.affiliation: Faculty of Chemistry, Adam Mickiewicz University, Poznań, Poland. franski@main.amu.edu.pl
authors.forename: Rafał
authors.initials: R
authors.lastname: Frański
authors.forename: Krystian
authors.initials: K
authors.lastname: Eitner
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Schroeder
authors.forename: Oles P
authors.initials: OP
authors.lastname: Szwajka