3-Sphere Tetrahedral Angles and Phase Angle of the Pseudorotation P[deg] of C₁-CH₃-α-D Ribitol Iminocyclitol

3-Sphere dihedral angles θHnHn+1[deg] calculated from NMR data, from vicinal coupling constant ³JHnHn+1[Hz] with right sign and stereochemistry, are used for simulation of the conformation of the five membered ring with VISION molecular models and Gausian09W. For a vicinal angle ϕ[deg], angle result from vicinal coupling constant ³JHnHn+1[Hz], result three possible dihedral angles with negative and positive sign. Different phase angles of the pseudorotation results from combination of dihedral angles (exocyclic angles) with positive and negative sign in case of cis stereochemistry, and only negative sign for trans stereochemistry, in accord with D-ribitol stereochemistry. The sign of the endocyclic trans-ee torsional angle is positive, relative to trans-aa and cis stereochemistry with same sign as exocyclic angle, as visualized on VISION molecular models. Tetrahedral angles φCn[deg] in close relationship with dihedral angles θHnHn+1[deg] are calculated only from vicinal coupling constant ³JHnHn+1[Hz] in attempt to corelate the change in conformation with tetrahedral values φCn[deg] and bond lengths l[A⁰], once the iminocyclitol push out from planarity one or two atoms of carbon, and once again to confirm the method for calculation of tetrahedral angles of five membered ring, sin/tan versus sin/cos units.