Synthesis, Characterization, and Photochemical and Computational Investigations of Ru(II) Heterocyclic Complexes Containing 2,6-dimethylphenylisocyanide (CNx) Ligand

Abstract

The isocyanide ligand forms complexes with ruthenium(II) bis-bipyridine of the type [Ru(bpy)(2)(CNx)Cl](CF(3)SO(3)) (1), [Ru(bpy)(2)(CNx)(py)](PF(6))(2) (2), and [Ru(bpy)(2)(CNx)(2)](PF(6))(2) (3) (bpy = 2,2'-bipyridine, py = pyridine, and CNx = 2,6-dimethylphenylisocyanide). The redox potentials shift positively as the number of CNx ligands increases. The metal-to-ligand charge-transfer (MLCT) bands of the complexes are located at higher energy than 450 nm and blue shift in proportion to the number of CNx ligands. The complexes are not emissive at room temperature but exhibit intense structured emission bands at 77 K with emission lifetimes as high as 25 micros. Geometry optimization of the complexes in the singlet ground and lowest-lying triplet states performed using density functional theory (DFT) provides information about the orbital heritage and correlates with X-ray and electrochemical results. The lowest-lying triplet-state energies correlate well with the 77 K emission energies for the three complexes. Singlet excited states calculated in ethanol using time-dependent density functional theory (TDDFT) and the conductor-like polarizable continuum model (CPCM) provide information that correlates favorably with the experimental absorption spectra in ethanol.

Influence of the Protonic State of an Imidazole‐Containing Ligand on the Electrochemical and Photophysical Properties of a Ruthenium(II)–Polypyridine‐Type Complex

“…The nature of these states was precised by analysis of the corresponding spin-orbitals and spin density distributions, as done by other authors, for instance ref. [53].…”

Excited States from Time‐Dependent Density Functional Theory

“…Using the TDKS equations [31], one finds that the time evolution of g s is governed by the von Neumann equation:…”

“…Most are in the linear response regime. In inorganic chemistry, the optical response of many transition metal complexes [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] has been calculated, as have some X-ray absorption spectra. 36,37 In organic chemistry, heterocycles [38][39][40][41][42][43] have been examined among others, [44][45][46] including the response of thiouracil, 47 s-tetrazine, 48 and annulated porphyrins.…”

An Experimental and Density Functional Theory Approach Towards the Establishment of Preferential Metal‐ or Ligand‐Based Electron‐Transfer Processes in Large Quinonoid‐Bridged Diruthenium Complexes [{(aap)2Ru}2(μ‐BL2–)]n+ (aap = 2‐Arylazopyridine)

“…A selected list of vertical excitation energies computed with the TD-DFT/B3LYP formalism for the B3LYP/SDD,6-31G* geometry of [1a] 2+ in its singlet ground state are summarized in Table 9 (complete lists are given in Table S5 in the Supporting Information). [39] Here, a comparison between observed and computed transitions is performed by examining transitions of comparable intensities guided by their respective oscillator strengths and absorptivity values. [40] The nature of the excited states is assigned based on the percent Kohn-Sham orbital contributions of the orbitals involved in the electronic transitions.…”