Site‐Selective Ligand Exchange on a Heteroleptic TiIVComplex Towards Stepwise Multicomponent Self‐Assembly

A series of heteroleptic [Ti12X]−complexes have been selectively constructed from a mixture of TiIVions, a pyridyl catechol ligand (H21; H21=4‐(3‐pyridyl)catechol), and various bidentate ligands (HX) in the presence of a weak base, in addition to a previously reported [Ti12(acac)]−(acac=acetylacetonate) complex. Comparative studies of these TiIVcomplexes revealed that [Ti12(trop)]−(trop=tropolonate) is much more stable than the [Ti12(acac)]−complex, which allows the replacement of acac with trop on the [Ti12(acac)]−complex. This TiIV‐centered site‐selective ligand exchange reaction also takes place on a heteronuclear PdIITiIVring complex with the preservation of the PdII‐centered coordination structures. Intra‐ and intermolecular linking between two TiIVcenters with a flexible or a rigid bis‐tropolone bridging ligand provided a tetranuclear and an octanuclear PdIITiIVcomplex, respectively. These higher‐order structures could be efficiently constructed only through a stepwise synthetic route.