Reactive collisions in quadrupole cells 5. Reactions of singly charged transition metal ions with cyclopentene

Abstract

The development of a tandem mass spectrometric method, involving reactive collisions in a quadrupole collision cell, to study the reactions of metal ions with organic substrates is reported. This approach is evaluated by studying the reactions of singly charged transition metal ions with cyclopentene. The transition metal ions Sc + through Cu + were produced by fast atom bombardment of the appropriate solid metal chloride. After mass selection of these metal ions by the double-focusing (BE) stage of a hybrid BEqQ mass spectrometer, the metal ions were introduced into the r.f.-only quadrupole collision cell (q) at low injection energy where they underwent reaction with cyclopentene. The reaction products were mass analyzed by the final quadrupole (Q). The Mn + ion was largely unreactive with cyclopentene. The major primary product for the metal ions Sc +, Ti +, V +, Fe +, Co + and Ni + was M +(C 5H 6) arising by reductive H 2 elimination from the M +(c-C 5H 8) complex. Cr + and Cu + showed only clustering to form M +(C 5H 8). This difference in reaction mode has been rationalized in terms of the energetics of insertion of the metal ion into a CH bond. The M +(C 5H 6) product reacted further with cyclopentene to produce M +(C 5H 5) 2, presumably the ionized metallocene, except for Co +(C 5H 6) which also produced Co +(C 5H 6) 2 and Ni +(C 5H 6) which produced only Ni +(C 5H 6)(C 5H 8). Cr +(C 5H 8). Cr +(C 5H 8) and Cu +(C 5H 8) underwent further clustering with cyclopentene. Where comparison is possible, the results obtained are in good agreement with results obtained in earlier studies, indicating that the present tandem mass spectrometric method is a viable approach to the study of metal ion/organic molecule reactions.