名称:
Badly behaving bipyridine: the surprising coordination behaviour of 5,5′-substituted-2,2′-bipyridine towards iron(II) and ruthenium(II) ions
摘要:
A new tetrapyridine ligand, 5,5-(3-pyridyl)-2,2-bipyridine (2) was prepared from 5,5-dibromo-2,2-bipyridine (1) via Pd(0)-mediated Suzuki coupling. The reaction was performed either directly upon the free ligand, or upon its Ru(II) complex. The structures of [Ru(1)(3)](PF6)(2) and [Ru(2)(3)](PF6)(2) were studied in solution by NMR, and in the solid state by single crystal X-ray diffraction. Solution NMR data suggests distorted structures, consistent with the observed slow reactivity of the ligands towards Ru(II) ions, and their reluctance to coordinate to Fe(II) ions. However, solid-state X-ray data indicated little distortion from ideal geometries, suggesting the effect may be more electronic than steric in nature.