s . The cross-correlated relaxation rates were calculated from equation 11 with effective C-H and H-H distances of r CH = 1.115 Å and r HH = 1.821 Å, and angle between the C-H bond and the methyl rotation axis of θ CH = 110.5°, see Zhang and coworkers. The strong coupling methyl groups at 800 MHz field were excluded from the analysis and are reported in Tables and in the supporting information. The current implementation of NMR relaxation computation is available on github ().