Acetonitrile (CH 3 CN, ACN) is one of the most commonly used dipolar aprotic solvents, and is used extensively both in basic research and in industry. In the gas phase, the ACN molecule has a large dipole moment of 3.92 D 1 and polarization e↵ects are expected to increase the dipole moment in the liquid significantly. This leads to a relatively large dielectric constant and results in high solubility of electrolytes. As a result, ACN is widely used in batteries. In the solid phase, the monoclinic ↵-ACN crystal is the most stable structure in which the molecules are oriented in an antiparallel alignment in the plane spanned by the b and c axes, while there is mainly dispersion interactions between the molecules in the a direction(see fig. ). ACN is also a prevalent solvent in photophysical and photochemical experiments, Figure 1: Crystal structure of the ↵-phase of acetonitrile.