Hydrogen bonding with polonium†
Hydrogen bonding (H-bonding) with heavier chalcogens such as polonium and tellurium is almost unexplored owing to their lower electronegativities, providing us an opportunity to delve into the uncharted territory of X–H⋯Po/Te H-bonds (X–H, X = O, N, C). Employing high-level quantum mechanical calculations that include dispersion correction and the relativistic effect and considering dimethyl polonium (Me2Po) as the model H-bond donor, we have provided evidence of the X–H⋯Po H-bonds for the first time. The H-bond energies can be as much as 30 kJ mol−1, which is energetically comparable to any conventional H-bonds. It is counterintuitive from the perspective of low electronegativity of polonium but possible if one considers the contributions from polarizability, dispersion, and the relativistic effect. We strongly believe that these fundamental studies are expected to impact polonium chemistry, such as in marine science, as dimethyl polonium is one of the major chemicals produced by aerobic marine microorganisms and tracer applications of polonium for environmental carbon cycles.