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Desymmetrization of an Octahedral Coordination Complex Inside a Self‐Assembled Exoskeleton
Author(s) -
Johnstone Mark D.,
Schwarze Eike K.,
Ahrens Jennifer,
Schwarzer Dirk,
Holstein Julian J.,
Dittrich Birger,
Pfeffer Frederick M.,
Clever Guido H.
Publication year - 2016
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201602497
Subject(s) - chemistry , crystallography , octahedron , supramolecular chemistry , coordination geometry , ligand (biochemistry) , coordination sphere , cationic polymerization , octahedral molecular geometry , nuclear magnetic resonance spectroscopy , stereochemistry , hydrogen bond , molecule , crystal structure , polymer chemistry , organic chemistry , biochemistry , receptor
The synthesis of a centrally functionalized, ribbon‐shaped [ 6 ]polynorbornane ligand L that self‐assembles with Pd II cations into a {Pd 2 L 4 } coordination cage is reported. The shape‐persistent {Pd 2 L 4 } cage contains two axial cationic centers and an array of four equatorial H‐bond donors pointing directly towards the center of the cavity. This precisely defined supramolecular environment is complementary to the geometry of classic octahedral complexes [M(XY) 6 ] with six diatomic ligands. Very strong binding of [Pt(CN) 6 ] 2− to the cage was observed, with the structure of the host–guest complex {[Pt(CN) 6 ]@Pd 2 L 4 } supported by NMR spectroscopy, MS, and X‐ray data. The self‐assembled shell imprints its geometry on the encapsulated guest, and desymmetrization of the octahedral platinum species by the influence of the D 4 h ‐symmetric second coordination sphere was evidenced by IR spectroscopy. [Fe(CN) 6 ] 3− and square‐planar [Pt(CN) 4 ] 2− were strongly bound. Smaller octahedral anions such as [SiF 6 ] 2− , neutral carbonyl complexes ([M(CO) 6 ]; M=Cr, Mo, W) and the linear [Ag(CN) 2 ] − anion were only weakly bound, showing that both size and charge match are key factors for high‐affinity binding.