Orientational Self-Sorting in Octahedral Coordination Cages Based on Small, Heteroditopic N-Donor Ligands

Coordination cages based on heteroditopic N-donor ligands can potentially form isomers, which differ in the relative orientation of the ligands. We have explored the construction of octahedral cages using small low-symmetry N-donor ligands (L). When the ligands were combined with Pd(CH3CN)42, hexanuclear Pd6L12-type cages were obtained as a mixture of isomers, as evidenced by NMR spectroscopy and single-crystal X-ray crystallography. Attempts to resolve the isomers by cyclic ion mobility-mass spectrometry (cIM-MS) are described. Structurally defined cages of the general formula Pt2Pd4Cl8L84 were formed in kinetically controlled reactions of homoleptic PtL42 complexes with PdCl2(CH3CN)2. Crystallographic analyses of the products have revealed antipodal Pt2+ centers, the pyridine or pyrimidine donor groups of the bridging ligands being exclusively bound to the four equatorial PdCl2 complexes.