Resonance capture of electrons by cyclopentadienyltricarbonylmanganese and -rhenium derivatives

Abstract

Negative ion mass spectra of cyclopentadienyltricarbonylmanganese and-rhenium derivatives RC5H4M(CO)3 (R=H, CN, COOH, COMe, COOMe, CH2OH, CHO; M=Mn, Re) were studied. The subsequent detachment of carbonyl groups is the main process of the fragmentation of these compounds under the conditions of the resonance capture of electrons. On going fron the rhenium complexes to manganese derivatives, the maxima of the yields of the ions [M-nCO]− (n=1–3) shift to the lower energy region indicating that the stability of the Re−CO bond is higher than that of Mn−CO. The average lifetimes of the molecular negative ions relative to the autodetachment of an electron (τa) and to dissociation (τd) were measured. It was found that electron-accepting substituents increase the τa value and decrease τd.