Conjugated pyridines with an end-capping ferrocene

This study reports the synthesis of new pyridyl ligands incorporating an alkyne entity with an end-capping ferrocenyl moiety: 1-(ferrocenylethynyl)-4-((4-pyridyl)ethynyl)benzene (FEPEB), 1-ferrocenyl-6-(4-pyridyl)hexatriyn (FPHT), and 1-ferrocenyl-4-(4-pyridyl)butadiyne (FPBD). The complexes W(CO)(4)(L)(FEPEB) (L = CO, PPh(3), P(OMe)(3), PMe(3)), W(CO)(4)(L)(FPHT) (L = CO, PPh(3), P(OMe)(3), PMe(3)), and W(CO)(5)(FPBD) are obtained by ligating FEPEB, FPHT, and FPBD to W(CO)(4)(L)(THF). The energy of tungsten metal to pyridyl pi* charge transfer (MLCT) depends an both the pyridyl ligand and the ancillary ligand, L, Treating FPHT and FPBD with Mel causes N-methylpyridinium derivatives to form, which exhibit a strong low-lying charge-transfer band. As a comparative study, the complexes 1-(ferrocenylethynyl)-4-((4-nitrophenyl)ethynyl)-benzene (FENEB) and 1-(ferrocenylethynyl)-4-((4-aminophenyl)ethynyl)benzene (FEAEB) have also been synthesized. X-ray analysis has been employed to examine the structures of 1-(ferrocenylethynyl)-4-ethynylbenzene, W(CO)(4)(PPh(3))(FEPEB), W(CO)(5)(FPHT), and 1,8-diferracenyloctatetrayne.