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Fig. 1 The propylene oxide molecule: in white the hydrogen atoms; in grey the carbons C1, C2
and C3; in red the oxygen
Fig. 2 The propylene oxide is represented as a distorted tetrahedron, whose vertices are the H, O,
C2, and C3; the edges are indicated by thick black lines. The leading configurations are classified as
V, E and F. The four V configurations correspond to the rare-gas atom directed through the vertices
of the tetrahedron and the center-of-mass of the molecule (black dot); in V1 the rare-gas atom is
directed through C3, in V2 through C2, in V3 through O, and in V4 through H (the direction of
the V configurations are indicated by a black line). The six leading configurations E correspond
to the direction (red line) connecting the center-of-mass of the molecule and the centers-of-mass
of the six edges of the tetrahedron (red dots). The four leading con-figurations F correspond to the
direction (blue line) connecting the center-of-mass of the molecule and the centers-of-mass of the
faces of the tetrahedron (blue dots)