Synthesis and Properties of Achiral Asymmetric Dinuclear Tris(1-pyrazolyl)methane Complexes of Ru(II).

Exploiting the “complexes-as-metals/complexes-as-ligands” synthetic strategy [1] a family of six novel polypyridyl dinuclear species containing two different Ru tpm)(CL) units [tpm = tris(1- pyrazolyl)methane, CL = 2,2’-bipyridine, 1,10-phenanthroline, 2,2’-biquinoline] bridged either by 4,4’-bipyridine or pyrazine (see the chart) have been prepared as hexafluorophosphate salts. These compounds re-present the asymmetric analogues of six dinuclear complexes whose synthesis and properties have been recently published. Notably, owing to the presence of a tripodal ligand, the metal centres are not chiral, thus the samples are not diastereomeric mixtures, a feature that prevents the structural characterization of oligonuclear trischelate complexes. All novel complexes have been thoroughly characterized by elemental analyses and IR spectroscopy, and their 1H NMR spectra completely assigned on the basis of COSY and NOESY experiments. The photophysical, electrochemical, and spectroelectrochemical properties of the new species have also been studied.