Living in a Cage Is a Restricted Privilege - Beauty in Chemistry - page 153

Fig. 33 Crystal structures of the inclusion complexes involving the hexaprotonated form of the
bistren derivative 19 and bromide (a), and azide ions (d)[ 70 ]. The six secondary amine groups are
protonated. All hydrogen atoms have been omitted for clarity. (b, c, e, f) Triangles have been
obtained by linking the nitrogen atoms of the ammonium groups of each tren subunit. (c, f) y is the

torsion angle for each pair of triangles

Fig. 34 Cascade process for the formation of a ternary dicopper(II) bistren cryptate, including an
ambidentate anion. The bistren cryptand 20 has been chosen as an example

upon pH) occupies the apical position left available in each [Cu II tren] 2+ moiety.
Then, an ambidentate anion can displace the two labile solvent molecules, to bridge
the two metal centres, giving rise to a ternary complex (step ii in Fig. 34 ), complet-
ing the cascade process.
Figure 35a shows the crystal structure of the bistren derivative 20 alone, which
discloses an elongated ellipsoidal cavity [ 71 ]. It appears, at the first sight, that the