Rutheniumethynyl‐Triarylamine Organic−Inorganic Mixed‐Valence Systems: Regulating Ru‐N Electronic Coupling by Different Aryl Bridge Cores

Abstract

Four rutheniumethynyl-triarylamine complexes 1-4 with different aryl bridge cores were prepared. The solid structures of complexes 2-4 were fully confirmed by X-ray single-crystal diffraction analysis. Two consecutive one-electron oxidation processes of complexes 1-4 were attributed to the ruthenium and nitrogen centers, as revealed by cyclic voltammetry and square-wave voltammogram. Results also showed decreasing potential difference ΔE of complexes 1, 3, and 4, with the largest value for 2. Upon chemical oxidation of complexes 1-4 by 1.0 eq oxidation reagents FcPF 6 or AgSbF 6 , the mixed-valence complexes, except for 2 + , show characteristic broad NIR absorptions in the UV-vis-NIR spec-troscopic experiments. NIR multiple absorptions were assigned to NAr 2 !RuCp*(dppe) intervalence charge transfer (IVCT) and metal-to-ligand charge transfer transitions by TDDFT calculations. Coupling parameter (H ab) from Hush theory revealed that increasing electronic communication in 1 + , 3 + , and 4 +. Electron density distribution of the HOMO for neutral molecules (1, 3, and 4) and spin density distribution of the corresponding single-oxidized states (1 + , 3 + , and 4 +) increases progressively on the bridge as the size of the aromatic system increases, proving incremental contributions from bridge cores during oxidation.

Charge and Spin Delocalization in Mixed-Valent Vinylruthenium–Triarylamine-Conjugates with Planarized Triarylamines

“…109−111 Closely related alkynyl ruthenium−TA conjugates with Cp*(dppe)Ru−CC− instead of the {Ru}−CHCH− tag have also been scrutinized with respect to the MV properties of their associated radical cations and were found to have a more Ru-alkynyl centered oxidation with a concomitant bias of the unipositive charge and the unpaired spin density to the metal site and a concomitantly weaker electronic coupling. 112,113 We herein present three new congeners of vinylruthenium− TA conjugates with planarized TA substituents. These complexes were conceived with the expectation that a more coplanar arrangement of these two redox sites would foster delocalization and render the oxidized forms even stronger vis/ NIR absorbers than their conformationally more flexible counterparts.…”

(Spectro)electrochemical Properties of Anthracene Containing Triarylamine Platinum(II) Acetylides

“…Deconvolution shows that the broad absorptions in the region between 1000 nm (10.000 cm −1 ) and 2000 nm (5000 cm −1 ) are a composite of two or three individual charge transfer excitations. Comparison of the spectral characteristics in the NIR region of trans‐ 5 + and 6 + with 2 SiMe 3 + demonstrated, that the main contribution of the NIR absorption can be ascribed to a charge transfer excitation from the anthryl system to the triarylamino group [33,57] (see Table 3 entry ṽ 2 : 6800–7700 cm −1 ). For compound trans ‐ 5 + an additional low energy transition at 6050 cm −1 ( ϵ max =875 L mol −1 cm −1 , Δ 1/2 =1350 cm −1 ) can be observed, which is assigned to a ligand‐to‐metal‐charge‐transfer (LMCT) absorption from the anthryl functionality towards Pt 2+ [18,23] .…”

“…The spectroscopic data correspond with those reported previously. [26] 10-Trimethylsilyl(ethinyl)-9-N,N-di(p-anisyl)amino-anthracene (2SiMe 3 ): The compound was not synthesized according to the published procedure, [57] but following this synthetic protocol:, [33] [PdCl 2 (PPh 3 ) 2 ] (13 mg, 0.02 mmol, 1 mol-%) and CuI (21 mg, 0.11 mmol, 6 mol-%) were dissolved in dry, degassed diisopropylamine (45 mL) under an argon atmosphere and stirred at room temperature for 10 min. Anthracene 1 (891 mg, 1.84 mmol), trimethylsilylacetylene (0.3 mL, 2.02 mmol, 0.69 g mL À 1 ) and PPh 3 (29 mg, 0.11 mmol, 6 mol-%) were added in one portion to the yellow solution and the mixture heated to reflux overnight.…”

Anthracene‐Containing Gold(I) Triphenylphosphine Acetylide: Synthesis and (Spectro)electrochemical Properties

“…Deconvolution shows that the broad absorptions in the region between 1000 nm (10.000 cm À 1 ) and 2000 nm (5000 cm À 1 ) are composed of two individual charge transfer excitations. The observed spectral characteristics in the NIR region can be ascribed to a charge transfer excitation from the anthryl system to the triarylamine group [13,15] (v ˜2: 7325 cm À 1 , ε max = 5675 L mol À 1 cm À 1 , Δv ˜1/2 = 2000 cm À 1 ). At the higher energy side of the NIRspectrum another spectral component is characteristic and represents an additional charge transfer band from the anthracene π-system towards the triaryl amine functionality (v ˜3:…”

“…The synthesis of the ethynyl-(di-p-tolyl-amino)anthracene gold(I) complex 3 (Scheme 1) involved a two-step procedure similar to a synthetic approach described by us for the generation of related platinum complexes. [10] The TMS (= trimethylsilyl) protected acetylene 1SiMe 3 , which is accessible by a Sonogashira-Hagihara C,C cross-coupling reaction, [15][16][17] was reacted with tetrabutylammonium fluoride as a mild deprotection reagent [18,19] in order to form anthrylacetylene 1H. [13] In a ligand exchange reaction at [Au(PPh 3 )Cl] (2), the chlorido ligand was substituted by acetylide 1 À under basic conditions.…”