Pentaaza macrocyclic ytterbium(iii) complex and solvent controlled supramolecular self-assembly of its dimeric μ-η2:η2 peroxo-bridged derivatives

Abstract

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 with the formula of [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. For the first time the spectrum of the ²F_7/2 → ²F_5/2 transition has been obtained for a molecular complex of ytterbium with organic ligands in which all ligand-field components of the ground and excited state are well displayed at room temperature. This complex is capable of forming a dimeric peroxo Yb₂(μ-η²:η²-O₂)L₂⁴⁺ (2) derivative containing the biologically significant planar side-on doubly bidentate coordination mode of the peroxide. Inclusion of the appropriate solvent molecule into the crystal structure generates supramolecular architectures (2a–d) in which the solvent controlled self-assembly is observed. Spectral properties of these complexes were found to be very important and promising in the area of ytterbium physicochemistry.