**6. Correlations**

Isotope effects can also be correlated to other parameters related to, e.g., hydrogen bond strength and hydrogen bond energy.

Two-bond deuterium isotope effects on 13C chemical shifts are proportional to XH chemical shift. For an example see Figure 28. Another example is given in Ref. [71]. See also Figures 24 and 25.

**Figure 28.** Plot of two-bond deuterium isotope effects vs. OH chemical shifts of 10-hydroybenzo[h]quinolones. Taken from Ref. [71].
