Three novel pendant acetate complexes, [Rh­(bdmpza)­Cl3]−M+, [Rh­(bdmpza)­Cl2(py)], and [Ir­(bdmpza)­Cl3]−M+ (bdmpza = bis­(3,5-dimethylpyrazol-1-yl) acetate, M+ = Li+, Na+), were synthesized. Abstraction of halide from these complexes with silver salts yielded species capable of C–H activation of arenes. The catalytic H/D exchange reaction between benzene and trifluoroacetic acid-d was optimized, and these conditions were used to evaluate H/D exchange in other arenes. Branched alkyl substituents in alkyl aromatics showed an affinity toward deuterium exchange in the β-alkyl position only. DFT calculations were performed to determine the mechanism of H/D exchange.

In this extension to a classic physical chemistry experiment, students record the proton nuclear magnetic resonance spectra of the β-diketones 2,4-pentanedione, 3-methyl-2,4-pentanedione, and 3-chloro-2,4-pentanedione to investigate the effect of substituents on keto–enol tautomerization equilibria. From the integrated intensities of keto and enol methyl proton peaks, students calculate the equilibrium constant for each 2,4-pentanedione. The students then use the effects of electron-donating and electron-withdrawing substituents to elucidate the nature of keto–enol equilibria.

Reaction of Pt(dippe)(NBE)2 (NBE = norbornene) with a variety of esters leads to a product in which the less reactive C–O bond is cleaved to give Pt(dippe)(O2CR)(R′). A further disproportionation reaction occurs to eliminate R′2 and produce Pt(dippe)(O2CR)2. Details of the mechanisms of these reactions are explored.

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