Low-valence oxo-centred triruthenium complexes by bridging acetate substitution with pyrazolyldiazine or pyridinyltetrazine ligands

摘要

A series of oxo-centred triruthenium-acetate complexes with valence III,III,II were prepared by reactions of [Ru-3(III,III,III)](+) precursor [Ru3O(OAc)(6)(py)(2)(CH3OH)](+) (1) with 3-chloro-6-(pyrazol-1-yl)pyridazine (cppd), 3-chloro-6-(3,5-dimethylpyrazol-1-yl)pyridazine(cmppd), 3,6-bis(pyrazol-1-yl)pyridazine (ppd), 3,6-bis(3,5-dimethylpyrazol-1-yl)pyridazine (mppd) or 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine (bptz). When neutral Ru-3(III,III,II) precursor Ru3O(OAc)(6)(CO)(CH3OH)(2) (2) was utilized, a stable low-valence Ru-3(III,II,II) derivative complex was successfully isolated. As established through crystal structural analyses, they were derived from 1 or 2 by substitution of the axial methanol and one of six bridging acetates in the parent Ru-3(mu(3)-O)(mu-OAc)(6) cluster core as well as one axial pyridine in some cases. As revealed by electrochemical and spectroscopic studies, substituting one of the six bridging acetates in the parent Ru-3(mu(3)-O)(mu-OAc)(6) cluster core significantly modifies the electronic and redox characteristics. Compared with those for the parent compound [Ru3O(OAc)(6)(py)(3)](+), triruthenium-based redox potentials of these derivatives show remarkable positive shifts.