Intervalence Charge Transfer (IVCT) in Ruthenium Dinuclear and Trinuclear Assemblies Containing the Bridging Ligand HAT {1,4,5,8,9,12‐hexaazatriphenylene}

Abstract

The IVCT characteristics of the mixed-valence forms of the dinuclear [{Ru(bpy)(2)}(2)(mu-hat)](n+) and the trinuclear [{Ru(bpy)(2)}(3)(mu-hat)](n+) species {HAT = 1,4,5,8,9,12-hexaazatriphenylene; bpy = 2,2'-bipyridine} show a marked dependence on the nuclearity, and in the trinuclear case on the extent of oxidation. Small differences are also found between the diastereoisomers of the dinuclear complex {meso (DeltaLambda) and rac (DeltaDelta/LambdaLambda)}, and between the homochiral (Delta(3)/Lambda(3)) and heterochiral (Delta(2)Lambda/Lambda(2)Delta) diastereoisomers of the trinuclear case. The strong metal-metal interactions result in unusual spectroscopic and electrochemical properties of the singly-oxidised (+7) and doubly-oxidised (+8) trinuclear mixed-valence species. A qualitative localised bonding description based on the geometrical properties of the dpi(Ru(II/III)) orbitals is invoked to explain the IVCT behaviour in the di- and trinuclear systems.

Probing the Transition between the Localised (Class II) and Localised‐to‐Delocalised (Class II–III) Regimes by Using Intervalence Charge‐Transfer Solvatochromism in a Series of Mixed‐Valence Dinuclear Ruthenium Complexes

“…[71] An account of the procedure employed in the spectroelectrochemical measurements has been detailed previously. [72] Solutions for the spectroelectrochemial experiments contained 0.02 m [(n-C 4 H 9 ) 4 The analysis and spectral deconvolution of the data were performed as described in a previous report.…”

“…[72] Based on the reproducibility of the parameters obtained from the deconvolutions, the uncertainties in the energies (n max ), intensities {(e/n) max } and bandwidths (Dn 1/2 ) were estimated as AE 10 cm À1 , AE 0.001 m À1 cm À1 and AE 10 cm…”

Diastereoisomers as probes for solvent reorganizational effects on IVCT in dinuclear ruthenium complexes

“…The absorption spectra of the electrogenerated mixed-valence species were obtained in situ by the use of an optically semi-transparent thin-layer electrosynthetic (OSTLE) cell (path length 0.685 mm) mounted in the path of the spectrophotometer [54,55].…”

The Effective Electron‐Transfer Distance in Dinuclear Ruthenium Complexes Containing the Unsymmetrical Bridging Ligand 3,5‐Bis(2‐pyridyl)‐1,2,4‐triazolate

“…[71] An account of the procedure employed in the spectroelectrochemical measurements has been detailed previously. [72] Solutions for the spectroelectrochemial experiments contained 0.1  [(n-C 4 H 9 ) 4 N]PF 6 supporting electrolyte in CH 3 CN and the complex (ca. 1·10 -3 ).…”

“…[17] The IVCT spectra were scaled as ͐ε(ν)/ν·dν [14,73] and deconvolution of the NIR transitions was performed using the curve-fitting subroutine implemented within the GRAMS32 commercial software package. [72] On the basis of the reproducibility of the parameters obtained from the deconvolutions, the uncertainties in the energies ν max , intensities (ε/ν) max and bandwidths ∆ν 1/2 were estimated as ±10 cm -1 , ±0.001  -1 and ±10 cm -1 , respectively. The transition moment |µ 12 | in e·Å is defined by Equation (ii) where the zeroth-moment, M 0 , represents the area under the band of the reduced absorption spectrum.…”