Chromium(VI) is a carcinogen and mutagen, and its mechanisms of action are proposed to involve binding of its reduction product, chromium(III), to DNA. The manner in which chromium(III) binds DNA has not been established, particularly at a molecular level. Analysis of oligonucleotide duplex DNAs by NMR, EPR, and IR spectroscopies in the presence of chromium(III) allows the elucidation of the Cr binding site. The metal centers were found to interact exclusively with guanine N7 positions. No evidence of chromium interactions with other bases or backbone phosphates nor of Cr forming intra‐strand crosslinks between neighboring guanine residues was observed.

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Recently, several studies on the effects of a compound named "chromium malate," with the proposed formula "Crmalate·xHO" where x = 3.5 or 5, on the health of healthy and diabetic rats have appeared. However, the compound is poorly characterized, and knowing the identity of this material could be important in the interpretation of the previous and of future studies on the effects of this compound in animals. Consequently, the synthesis, characterization, and identity of this material were explored. A combination of spectroscopic, magnetic, and elemental analyses and mass spectral studies reveal that the compound is probably a polymer, not a discrete molecule, and does not have the composition previously reported. The repeating unit of the polymer possesses an antiferromagnetically coupled trinuclear Cr(III) core. The current study suggests that previous reports on chromium malate and its effects in animals must be viewed with caution.

Chromate compounds are carcinogenic when inhaled, but the mechanism of tumorigenesis is unknown. One hypothesis involves transport of chromium into cells where reduction to chromium(III) and binding of the chromium(III) to DNA occurs. The elucidation of the molecular‐level structures of the resulting metal–DNA adducts forms a crucial bridge between exposure to the carcinogen and the development of mutations and cancer in humans. More information can be found in the communication by J. B. Vincent et al. on page 628 in Issue 5, 2020 (DOI: 10.1002/cbic.201900436).