MJG, JHK, and WHG gratefully acknowledge financial support from the National Science Foundation's Environmental Chemical Sciences Program through grant 1709993. MJG also acknowledges NSF support through a Graduate Research Fellowship (Grant No. 1122374). NWY and WHG acknowledge financial support from BP through its participation as a Founding Member of the MIT Energy Initiative. The authors gratefully acknowledge Shamel Merchant for helpful guidance on the quantum calculations, and Oliver Welz for sharing the geometries from his calculations with us.