Mass spectrometry of γ-Complexes of transition metals : XXII. Fragmentations of ferrocenyl-substituted pyrazolines-2 under electron impact

The mass spectra of 1-N-acetyl- and 1-N-phenyl-3-ferrocenyl-5-arylpyrazolines-2, their 5-ferrocenyl-3-aryl isomers and their 3,5-diferrocenyl analogues have been studied. The “pyrazoline” type of the molecular ion fragmentation involves various processes of heterocyclic nucleus destruction and elimination of the substituents or their fragments. The directions and intensifies of the processes observed are interpreted in terms of preferred positive charge localization on the transition metal atom. Interactions between the acetyl and ferrocenyl groups manifest themselves by the appearance of intense P  C₅H₅]⁺ ions (ferrocenyl type fragmentation products) in the mass spectra of 1-N-acetyl-3-aryl-5-ferrocenylpyrazolines-2 only. The fragmentation mechanism leading from P  C₅H₅]⁺ to C₇H₇OFe⁺ is discussed.