Synthesis, characterization and catalytic property of ruthenium-terpyridyl complexes

The known compound 4′-(carboxyphenyl)-2,2′:6,2″-terpyridine (LH) was prepared and complexed with RuCl₃.3H₂O. The resulting complex [Ru(LH)Cl₃] was then allowed to react separately with 2,2′-bipyridine (bpy), 1,10-phenanthroline (phen), triphenylphosphine (PPh₃) and 1,2-bis-(diphenylphosphino)ethane (dppe). The compositions of corresponding complexes [Ru(LH)bpyCl](BF₄) 1, [Ru(LH)phenCl](BF₄) 2, [Ru(LH)(PPh₃)(CH₃CN)₂] (BF₄)₂3 and [Ru(LH)(dppe)Cl](BF₄) 4 were assigned on the basis of their FAB-mass spectra, elemental analysis, spectroscopic (IR, NMR) data and X-ray diffraction measurements. The diamagnetic, cationic complexes displayed strong MLCT transitions in the visible region with significant shift in MLCT band energy corresponding to the strength of substituted ligands. The redox behaviour of the complexes was investigated using cyclic voltammetry measurements. Among all the complexes, 3 efficiently catalyzed the synthesis of propargylamine via three components coupling reaction.