Experimental and DFT calculated structure of the diruthenium(2.5) complex [(Me₃TACN)Ru(μ‐Cl)₃Ru(Me₃TACN)](PF₆)₂

Abstract

The diruthenium(2.5) complex [(Me3TACN)Ru(μ‐Cl)3Ru(Me3TACN)]‐(PF6)2, Me3TACN = 1,4,7‐trimethyl‐1,4,7‐triazacyclononane, has been crystallized for structural characterization. The results are reproduced by density functional theory (DFT) calculations and confirm the sensitivity of the central Ru(μ‐Cl)3Ru core to contacts between the Cl bridging atoms and the co‐ligands. The singly occupied MO is characterized as a σ* MO involving the metal dz2 orbitals and a small halide contribution by DFT calculations and EPR.

Ruthenium(II) Isocyanide Complexes Supported by Triazacyclononane/Trithiacyclononane and Aromatic Diimine: Structural, Spectroscopic, and Theoretical Studies

“…In this work, the ∠Ru−Cl−Ru and ∠Cl−Ru−Cl of [(Me 3 Tacn)Ru(μ-Cl) 3 Ru(Me 3 Tacn)] + ( 5 ) are 80.32(3)−80.81(4)° and 82.03(5)−83.02(4)°, respectively, revealing that the complex is elongated along the Ru−Ru axis. The Ru···Ru distance for the homovalent (Ru II Ru II ) complex 5 (3.1842(6) Å) is significantly longer than those for the corresponding mixed-valent congeners [(Me 3 Tacn)Ru(μ-Cl) 3 Ru(Me 3 Tacn)] 2+ (2.8862(11), 2.8939(8) Å) and [(Tacn)Ru(μ-Cl) 3 Ru(Tacn)] 2+ (2.830(1) Å), of which metal−metal formal bond orders of 0.5 were proposed on the basis of a simple molecular orbital scheme for Ru 2 complexes with D 3 h symmetry (Figure ). , Interestingly, the Ru···Ru distance in 5 is among the lowest reported for binuclear Ru II Ru II complexes containing the [Ru(μ-Cl) 3 Ru] core. For example, the Ru···Ru distance in 5 is shorter than those in [(PMe 3 ) 3 Ru(μ-Cl) 3 Ru(PMe 3 ) 3 ] + (3.374(6) Å), [(η 6 -C 6 H 6 )Ru(μ-Cl) 3 Ru(η 6 -C 6 H 6 )] + (3.287(1) Å), and [(AsMe 3 ) 3 Ru(μ-Cl) 3 Ru(AsMe 3 ) 3 ] + (3.263(1) Å) by 0.08−0.19 Å.…”

“…It was then found out that the dicationic complex could be obtained by refluxing [Ru(Me 3 Tacn)Cl 3 ] in ethylene glycol alone. In the literature, the oxidation states for the Ru centers in the mixed-valent complex [(Me 3 Tacn)Ru(μ-Cl) 3 Ru(Me 3 Tacn)] 2+ were assigned as +2.5. , The reduction of the Ru centers from +3 to +2.5 upon the formation of [(Me 3 Tacn)Ru(μ-Cl) 3 Ru(Me 3 Tacn)] 2+ should be due to the reducing power of ethylene glycol. However, the reducing power of ethylene glycol is not high enough to reduce both Ru centers to +2, and the monocationic complexes [(Me 3 Tacn)Ru(μ-Cl) 3 Ru(Me 3 Tacn)] + ( 5 ) have to be prepared by reducing [(Me 3 Tacn)Ru(μ-Cl) 3 Ru(Me 3 Tacn)] 2+ by Zn powder (Scheme ).…”