Abstract
On the basis of the main concepts of molecular topology a simple mathematical formalism for quantitative interpretation of experimental intramolecular dipolar 13C spinlattice-relaxation times T 1 DD has been developed. Rotational molecular motions in liquids are no longer described with respect to three orthogonal main axes. New so-called topographic axes have been defined; the number of these axes and their location in the molecule under consideration can be derived from the molecular structure. The preference of the topographic axes as rotational axes can be calculated from molecular geometry without any knowledge of experimental T 1 DD times. A new topological index allows the quantitative reproduction of experimental intramolecular T 1 DD times providing information about the overall anisotropic rotational motions of molecules and internal rotations. Experimental T 1 DD times for toluene at a temperature range from 183 to 303 K have been reproduced, the deviation between calculated and observed values being only about 1%, considerably less than the experimental error of at least 10%.
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