Studying a Ligand Substitution Reaction with Variable Temperature 1H NMR Spectroscopy: An Experiment for Undergraduate Inorganic Chemistry Students

Document Type

Article

Publication Date

7-1-2003

Publication Title

Journal of Chemical Education

DOI

10.1021/ed080p803

ISSN

1938-1328

Abstract

The study of ligand substitution reactions of transition metal complexes is often a significant component of undergraduate courses in inorganic chemistry. In the laboratory, many undergraduates have studied the aquation of [Co(NH3)5Cl]2+at elevated temperatures, taking aliquots of the reaction mixture, and obtaining a series of UV–vis spectra. Recently, an improved synthesis of a similar complex, trans-[Co(NH3)4Cl2]+ was reported. This complex undergoes aquation in less than an hour at room temperature, much faster than [Co(NH3)5Cl]2+, and is readily monitored by 1H NMR spectroscopy. This reaction forms the basis of an instructive, multi-week laboratory experience in inorganic synthesis, followed by an analysis of a reaction mechanism using a classical activation parameter determination.

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