A Critical Appraisal of Dimolybdenum Tetraacetate Application in Stereochemical Studies of -Diols by Circular Dichroism.

This critical appraisal is intended for users of the dimolybdenum method, well-established in electronic circular dichroism (ECD) to determine the absolute configuration of -diols and, in particular, for experimental researchers not being experts in chiroptical methods. The main goal is to demonstrate how to avoid misleading and ambiguous conclusions resulting from the rigorous application of the helicity rule by limiting the analysis to the -diol unit alone. We particularly focused on multichromophoric systems, especially those that may interfere with the absorption of an formed dimolybdenum tetraacetate-diol complex. In this context, examples are presented of -diols for which stereochemical assignment based solely on the helicity rule is ambiguous and does not necessarily lead to correct results. The motivation for choosing these examples was to demonstrate the impact of the structure of the substrate on the complexation process with the metal core and its selectivity. For each selected case, results obtained are analyzed in detail together with a discussion of existing restrictions and choice of a support method to increase the credibility of the conclusion. Based on seven both educational and challenging examples, it was shown that the dimolybdenum methodology can also be effectively applied to complex chromophoric systems, provided that other chiroptical methods and/or computational support verify obtained results.