The unprecedented template action of ytterbium ion in the synthesis of pentaaza macrocyclic Schiff bases is exemplified by isolation and definitive identification of the seven-coordinate pentagonal bipyramidal complex of formula [YbLCl2]ClO4 (1), where L is 2,14-dimethyl-3,6,10,13,19-pentaazabicyclo[13.3.1.]nonadeca-1(19),2,13,15,17-pentaene, providing the first example of crystallographically characterized pentaaza macrocyclic ytterbium complex. This complex is capable of forming the dimeric peroxo [Yb2L2(μ-η2:η2-O2)Cl2](ClO4)2 (2) derivative containing the biologically significant planar side-on doubly bidentate coordination mode of the peroxide. In the crystal structure, inclusion of the appropriate solvent molecule generates supramolecular architecture in which the solvent-controlled self-assembly is observed.