International audienceSeveral new redox-active Fe(κ2-dppe)(η5-C5Me5) arylacetylide complexes featuring pendant ethynyl (Fe(κ2-dppe)(η5-C5Me5)[{C≡C(1,4-C6H4)}nC≡CH] (1b-d; n = 1-3), Fe(κ2-dppe)(η5-C5Me5)[C≡C(1,3-C6H4)C≡CH] (2)) or ethenyl (Fe(κ2-dppe)(η5-C5Me5)[C≡C(1,4-C6H4)CH═CH2] (3)) groups have been synthesized and characterized under their Fe(II) and Fe(III) states. In contrast to the known ethynyl Fe(III) complex [Fe(κ2-dppe)(η5-C5Me5)(C≡CH)][PF6] (1a[PF6]), most of the new Fe(III) derivatives turned out to be kinetically stable in solution. A consistent picture of the electronic structure of the latter complexes in both redox states emerged from experimental data and DFT calculations. This study revealed that beyond the first 1,4-phenylene ring, modification or extension of the carbon-rich linker using (4-phenylene)ethynylene spacers will have only a minor influence on their electronic properties in their ground state, while still maintaining some (weak) electronic interaction along the carbon-rich backbone

DFT calculations with long-range dispersion corrections have been used to analyze the structures and binding energies of rotaxanes featuring dimetal polyynediyl Pt 2 C n 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 hydrogenbonding 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.