As shown in SI Section 6, we narrowed down Fig. to a relevant regime of commonly adopted HB geometries in solvents for heavy atom distances of < 3.5 -4.0 Å. Based on AMOEBA MD simulations of oTN in water and methanol (see details in SI Section 1), the average HB distance decreases monotonically from 3.35 Å for side-on HBs (70°) towards 2.93 Å when head-on HBs are adopted. Our model (eq. 7) predicts ∆𝜈̅ 𝐻𝐵 ≈ -5 cm -1 for side-on HBs interacting with the C≡N's πorbitals [~ 70° for θ(C≡N---O)]. As the angle and distance concomitantly increase and decrease, respectively, the blueshift increases steadily, plateauing around 26 cm -1 for head-on HBs with θ(C≡N---O) > 170°. Furthermore, we also investigated the HB blueshift in the (rare) case of two simultaneous HBs with a nitrile by comparing DFT blueshifts with values derived using eq. 7 (SI Section 5): we found that summing ∆𝜈̅ 𝐻𝐵 for each HB was an accurate model, implying each H-bonding interaction can be treated independently.