Heteroligand Molecular “Stirrups” Using Conformationally Flexible Ditopic Pyridyl−Pyrazolyl Ligands

Heteroligand molecular “stirrups” form by the self-assembly of flexible ditopic ligands in combination with 4,4′-bipyridine and [(dppp)Pd)]2+. Crystallographic analysis shows that the ligands, bis[3-(4-pyridyl)pyrazolyl]-m-xylene (mXy4py3pz) and bis[4-(4-pyridyl)pyrazolyl]-p-xylene (pXy4py4pz) form complexes of the type [{(dppp)Pd}2(4,4′-bipy)(L)]·4OTf (1·4OTf and 2·4OTf, respectively) in the solid state, with remarkably similar structures considering the differences in substitution patterns between the two ligands. The self-assembly of both 14+ and 24+ is assisted by face-to-face π interactions on the exterior of the macrocycle between the phenyl rings of the dppp ligands and the pyridyl groups of the ditopic ligands.