Spectroscopic, Electrochemical, and DFT Studies of Oxo‐Centered Triruthenium Cluster Complexes with a Bis(tridentate) Triazine Ligand

Oxo‐centered triruthenium–acetate complexes with a tridentate or bis(tridentate) triazine ligand have been prepared by the reaction of [Ru 3 O(OAc) 6 (py) 2 (CH 3 OH)] + ([ 1 ] + ) with a triazine ligand [3‐(2‐pyridyl)‐1,2,4‐triazine (pytz), 3‐(2‐pyrimidinyl)‐1,2,4‐triazine (pmtz), or 5,5′,6,6′‐tetramethyl‐3,3′‐bi‐1,2,4‐triazine (bdmt)]. The dimeric complex [{Ru 3 O(OAc) 5 (py) 2 } 2 (μ 4 ‐pmtz)] 2+ ([ 5 ] 2+ ), an intercluster mixed‐valence complex ([Ru 3 III,III,II ‐pmtz‐Ru 3 III,III,III ] 2+ ) containing an asymmetric bis(tridentate) pmtz ligands involved in both μ‐η 1 (N),η 2 (N,N) and orthometalated μ‐η 1 (C),η 2 (N,N) bonding modes, was prepared by substitution of a bridging acetate in the parent Ru 3 O(OAc) 6 cluster core. Chemical or electrochemical reduction or oxidation of [ 5 ] 2+ gave one‐electron reduced product [ 5a ] + or oxidized species [ 5b ] 3+ , respectively. It is demonstrated that substitution of the bridging acetate by a triazine ligand has a remarkable impact on the electronic and redox characteristics of the triruthenium cluster derivatives. Electrochemical, UV/Vis/NIR spectra, and DFT computational studies demonstrated that there is a distinct cluster–cluster interaction between the two triruthenium cluster moieties across an asymmetric bridging bis(tridentate) triazine in the dimeric triruthenium cluster complex [ 5 ] 2+ .