Desymmetrization of an Octahedral Coordination Complex Inside a Self-Assembled Exoskeleton.

The synthesis of a centrally functionalized, ribbon-shaped [6]polynorbornane ligand L that self-assembles with Pd(II) cations into a {Pd2 L4 } coordination cage is reported. The shape-persistent {Pd2 L4 } 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.

Modular synthesis of linear bis- and tris-monodentate fused [6]polynorbornane-based ligands and their assembly into coordination cages.

A modular approach has been developed for the synthesis of rigid linear di- and tritopic ligands based on a fused [6]polynorbornane scaffold. The design provides up to three sites for installing functionality, including both "ends" and a "central" position with the advantage that each region can be independently addressed during synthesis. To illustrate the utility of the approach, both pyridyl and picolyl units were incorporated to provide six new ligands, with centers and ends either matched or mismatched.

Aggregation of donor base stabilized 2-thienyllithium in a single crystal and in solution: distances from X-ray diffraction and the nuclear Overhauser effect.

Various 2-thienyllithium derivatives were investigated in the solid state by X-ray diffraction and in solution by 2D NMR experiments. The determined structures of [(Et(2)O)Li(C(4)H(3)S)](4) (1), [(THF)(2)Li(C(4)H(3)S)](2) (2), [(DME)Li(C(4)H(3)S)](2) (3), [(TMEDA)Li(C(4)H(3)S)](2) (4), and [(PMDETA)Li(C(4)H(3)S)] (5) (DME = 1,2-dimethoxyethane, TMEDA = N,N,N',N'-tetramethylethylene-1,2-diamine, and PMDETA = N,N,N',N",N"-pentamethyldiethylenetriamine) were solved in nondonating toluene and provide firm ground for diffusion-ordered NMR spectroscopy as well as heteronuclear Overhauser enhancement NMR spectroscopy. The distance relation of nuclear Overhauser effects with a factor of r(-6) is employed to gain further insight into the aggregation degree of 1-5 in solution.