Preparation, properties, and reactions of metal-containing heterocycles: Part CVIII. A novel generation of rigid, nanoscaled 1,1′-ferrocenediyl-bridged bis(pyridine), bis(bipyridine), and bis(phenanthroline) ligands

Four novel, rigid, and conjugated 1,1′-ferrocenediyl-bridged, bis(pyridine), bis(bipyridine), and bis(phenanthroline) ligands 2 and 5–7 have been synthesized by palladium promoted CC coupling reactions and characterized by 1H-, 13C{1H}-NMR, FT-IR, and mass spectroscopy as well as by elemental analyses. Ligand 2 was prepared from 5-ethynyl-2,2′-bipyridine and 1,1′-diiodoferrocene, while compounds 5–7 were readily accessible by reactions between pre-constructed ferrocene 4 and 4-bromopyridine, 5-bromo-2,2′-bipyridine, and 3-bromo-1,10-phenanthroline, respectively. Treatment of 1,1′-diiodoferrocene with 1-ethynyl-4-triisopropylsilyl ethynyl-2,5-dipropoxybenzene resulted in the formation of the ferrocene derivative 3. Via a SiC bond cleavage in 3 in the presence of tetra-n-butylammonium fluoride in THF the intermediate 4 was obtained. Ligand 1·0.5H2O crystallizes in the triclinic space group with a=11.2711(10), b=13.3346(12), c=14.0879(14) Å, α=105.007(12), β=105.179(11), γ=105.218(10)°, V=1845.7 Å3, Z=2, R=0.0640, and wR2=0.1292.