Properties of Isolated Complexes B- XY How to Measure Them

Rotational constants G = A,BorC are inversely proportional to principal moments of inertia la through the expressions G = h/Sit Ia, where a refers to one of the three principal inertia axis directions a, b or c. The are related to the coordinates of the atoms i in the principal axis system via the 

In this section, we discuss the observed geometries, both angular (the relative orientation of the components B and XY in space) and radial (the distance between B and XY at the observed orientation) of complexes B XY. 

Attention will be paid to the systematic relationship of the geometries of B- XY to those of hydrogen-bonded complexes in the corresponding series B- HX, especially for angular geometries, which are dealt with in detail in Sects. 3.1, 3.2 and 3.3. Radial geometries are treated only in summary (Sect. 3.4) here, but a detailed analysis is available in [19]. 

The discussions of Sects. 3.1,3.2 and 3.3 are structured by reference to a set of rules that were proposed some years ago [103,104] for rationalising the angular geometries of hydrogen-bonded complexes of the type B- HX, where X is a halogen atom. These rules are as follows  

The equilibrium angular geometry of a hydrogen-bonded complex B- HX can be predicted by assuming that the axis of the HX molecule lies  

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