Two analogous Schiff bases, (S,E)-2-((1-hydroxy-3-methyl-1 1-diphenylbutan-2-ylimino)methyl)phenol (1) and (S Z)-2-hydroxy-64(1-hydroxy-3-methyl-1 1-diphenylbutan-2-ylamino)methylene)cyclohexa 2 4-dicnone (2) exist in the solid state as phenol-imino and keto-amine tautomers respectively Their crystal structures were solved using-the X-ray diffraction method Sample 1 forms orthorhombic crystals of space group P2(1)2(1)2(1) while 2 forms monoclinic crystals of space group P2(1) In each samplc one molecule is in the asymmetric unit of the crystal structure One-dimensional and two-dimensional solid state NMR techniques were used for structure assignment and for inspection of the C-13 and N-15 delta(a) of the chemical shift tensor (CST) values NMR study indicates that the span (Omega = delta(11) - delta(33)) and the skew (K = 3(delta(2) - delta(10/)Omega) arc extremely sensitive to change in the tautomeric form of the Schiff bases Theoretical calculations of NMR shielding parameters for 1 and 2 and a model compound with reduced aliphatic residue were performed using the CIAO method with B3LYP functional and 6-311++g(d p) basis sets From comparative analysis of the experimental and theoretical parameters it was concluded that the position of hydrogen in the intramolecular bridge has tremendous influence on C-13 and N-15 CST parameters Inspection of Q and K parameters allowed for the establishment of the nature of the hydrogen bonding and the assignment of the equilibrium proton position in the intramolecular bridges in the solid state