Table 1.

Arrhenius Parameters Derived from Fits of the 1/T₁ Data.

Compound	Group causing the relaxation	Ea (kcal/mol)	τ0−1 (s−1)	C (s−2)
3	OMe + BCO	2.5a
	OMeb	3.2	1.0 × 1012*	1.0 × 108*
3-d6	BCO	1.15c	2.5 × 1011*	6.8 × 108*
8	OMe	1.9	1.9 × 1011	1.4 × 108
8-d3	Me	1.35c	3.3 × 1011*	1.7 × 108*

^aApparent activation energy resulting from contributions of two groups.

^bObtained from the difference between compounds 3 and 3-d₆ (SI, Figure S8)

^cObtained from linear regression of the data.

^*Resulting from 1/T₁ data extrapolation using the Kubo-Tomita expression.