Efficient Route to Organometallic Cage Formation via C–H Activation-Directed Muticomponent Assembly Accompanying Aromatic Guest Encapsulation

Driven by C–H activation-directed self-assembly,
a series
of organometallic cages, 4a–4e, was
obtained from the reaction of [Cp*IrCl2]2 (1) and 2,4,6-tri­(4-pyridyl)-1,3,5-triazine (tpt) (2) with terephthal-bis-aromatic imine ligands 3a–3e in the presence of AgOTf (Tf = O2SCF3). The 1H NMR spectra of 4a–4d revealed that two isomers of the organometallic cages (symmetrical
isomer SI-4 and asymmetrical isomer ASI-4) are formed. Pure isomer can be isolated from their chloroform solution
of the product mixture by crystallization at low temperature. In the
resulting supramolecular assemblies, the two central triazine units
are very close, and the centroid···centroid distance
between the two triazine moieties is only 3.3 Å. These discrete
cages can form complexes with a wide variety of π-donor substrates,
including Pt­(acac)2, pyrene, and coronene. The transannular
separation between the centers of the triazine rings in the host–guest
complex is now enlarged to about 6.66 Å. The preparation of host–guest
systems in a one-pot procedure was accomplished. The 1:1 complexation
between the guest and host was confirmed by 1H NMR, elemental
analyses and single-crystal X-ray diffraction analyses (6⊂SI-4b, 7⊂SI-4b, and 6⊂SI-4c).