Kinetic study of the formation of dihydrogen from the reaction of [1.1]ferrocenophanes with strong acids. 2. Tensiometry, spectrometry, and deuterium exchange studies

Article abstract of DOI:10.1021/om00095a008

The kinetics of the reactions [1.1]ferrocenophane (I), 3,3′-trimethylene[1.1]ferrocenophane (II), and 2,2′-trimethylene[1.1]ferrocenophane (III) were studied by using tensiometric and spectrometric techniques at acid strengths that were lower than those used in the electrochemical investigation. 1 The results of these measurements are consistent with the three-step mechanism proposed for the formation of dihydrogen: a very fast initial protonation, a slower second protonation, and the elimination of dihydrogen as the rate-determining step. However, at the lower acid strengths, competing reactions occur. One of these very likely involves the comproportionation of the ferrocenophane and the dication followed by the decomposition of the resulting monocation. The nature of other competing reactions remains as an open question. Kinetic studies using deuteriated acids established a primary kinetic isotope effect, k_H/k_D, between 3 and 5, for compound I. The ring protons of the ferrocenophane undergo complete exchange in these media at a rate much faster than the rate for dihydrogen formation. No exchange of the methylene protons was observed.

Full text of DOI:10.1021/om00095a008

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Evaluation Only. Created with Aspose.PDF. Copyright 2002-2021 Aspose Pty Ltd.

Evaluation Only. Created with Aspose.PDF. Copyright 2002-2021 Aspose Pty Ltd.