Ruthenocene-Type Complexes of N-Fused Porphyrins

Ruthenocene-type hybrid complexes with N-fused porphyrinato ligands, [Ru(NFp)Cp] (NFp=N-fused porphyrin, Cp=cyclopentadienyl), have been prepared and characterized by NMR and UV/Vis/NIR spectroscopy, cyclovoltammetry, and X-ray crystallography. [Ru(NFp)Cp] is a common low-spin ruthenium(II) complex and shows strong aromaticity. The Ru–Cp distance (1.833 A) in [Ru(NFp)Cp] is comparable to that in [RuCp2] (1.840 A). DFT calculations on [Ru(NFp)Cp] showed the unequivocal contribution of the RuCp moiety as well as the NFp moiety to both the HOMO and LUMO, constructing a three-dimensional d–π conjugated system. The HOMO–LUMO gaps of [Ru(NFp)Cp] are insensitive to the substituents on the NFp ligand, which is illustrated spectroscopically as well as theoretically. This is in sharp contrast to the ligand precursor, the N-fused porphyrin, in which the HOMO–LUMO gap is affected by substituents in a similar manner to standard porphyrins and related macrocycles.