Arsenate Stabilization via Dynamic Covalent Chemistry

We report the synthesis of arsenic heterocycles derived from saccharides 2 – 4 and AsCl 3 . Compounds 5 and 6 are stable in aqueous solutions, DMSO, or methanolic solutions. However, NMR and HPLC studies revealed that intramolecular trans‐esterification processes leads to dynamic equilibria. Theoretical studies revealed that three arsenates and two arsoranes participate in these intramolecular equilibria and account for the experimental spectroscopy and HPLC results. Through the correlation between the experimental and theoretical 13 C NMR spectra, we proposed the speciation of arsenic Compounds 5 and 6 . Moreover, experimental and theoretical IR spectra demonstrated that arsenates 5 A and 6 A predominate in the solid state. QTAIM studies were performed to explain the chemical shifts in the 13 C NMR spectra. Biological studies suggest that the structural flexibility of Compounds 5 and 6 increase the cytotoxic and antiproliferative activities of these compounds.