A Metal-Capped Conjugated Polyyne Threaded through a Phenanthroline-Based Macrocycle. Probing beyond the Mechanical Bond to Interactions in Interlocked Molecular Architectures

DFT calculations with long-range dispersion corrections have been used to analyze the structures and binding energies of rotaxanes featuring dimetal polyynediyl Pt2Cn dumbbells threaded through a 1,10-phenanthroline-based macrocycle. Results indicate that (i) the threading of the organometallic wire hardly affects its geometric and electronic properties and (ii) the noncovalent binding energies between the axle and macrocycle not only arise from mechanical bonding enforced weak interactions derived from the close proximity of the sp carbon chain to the macrocycle atoms, but also include hydrogen-bonding contacts involving hydrogen atoms of the metal bound phosphine ligands of the former and the nitrogen and oxygen atoms of the latter. The optimized geometries of the rotaxane and macrocycle are compared to the corresponding crystal structures where available.