Electropolymerization of [Ru(bpy)(CO)2Cl2] (bpy=2,2′-bipyridine: a revisited trans versus cis(Cl) isomeric influence study

The mono-bipyridine bis carbonyl complex [Ru(bpy)(CO)₂Cl₂] exists in two stereoisomeric forms having a trans(Cl)/cis(CO) (1) and cis(Cl)/cis(CO) (2) configuration. In previous work we reported that only the trans(Cl)/cis(CO) isomer 1 leads by a two-electron reduction to the formation of [Ru(bpy)(CO)₂]_n polymeric film on an electrode surface. This initial statement was overstated, as both isomers allowed the build up of polymers. A detailed comparison of the electropolymerization of both isomers is reported here, as well as the reduction into dimers of parent stereoisomer [Ru(bpy)(CO)₂(C(O)OMe)Cl] complexes 3 and 4 obtained as side products during the synthesis of 1 and 2.     

Systematic tuning of the reactivity of [RuII(terpy)(N^N)Cl]Cl complexes

Abstract

The substitution behavior of the [Ru^II(terpy)(ampy)Cl]Cl (terpy = 2,2′:6′,2′′-terpyridine, ampy = 2-(aminomethyl)pyridine) complex in water with several bio-relevant ligands such as chloride, thiourea and N,N′-dimethylthiourea, was investigated and compared with the reactivity of the [Ru^II(terpy)(bipy)Cl]Cl and [Ru^II(terpy)(en)Cl]Cl (bipy =2,2′-bipyridine and en?=?ethylenediamine) complexes. Earlier results have shown that the reactivity and pK_a values of Ru(II) complexes can be tuned by a systematic variation of electronic effects provided by bidentate spectator chelates. The reactivity of both the chlorido and aqua derivatives of the studied Ru(II) complexes increases in the order [Ru^II(terpy)(bipy)X]^+/2+?<?[Ru^II(terpy)(ampy)X]^+/2+?<?[Ru^II(terpy)(en)X]^+/2+. This finding can be accounted for in terms of π back-bonding effects provided by the pyridine ligands. The activation parameters for all the studied reactions support an associative interchange substitution mechanism.     

Reaction of cis-Ru(bpy)2Cl2 with 1-phenyl 5-(aminophenyl) 9-(2-pyridyl) benzimidazole derivatives: crystal structures of N-(4-chlorophenyl) imidazo[1,5a] pyridine and cis-[Ru(bpy)2(MeCN)2](ClO4)2

Reaction of 1-phenyl 5-(aminophenyl) 9-(2-pyridyl) benzimidazole derivatives (2) with cis-Ru(bpy)₂Cl₂ in MeCN results in the formation of N-(aryl) imidazo[1,5a] pyridine derivatives (4) and cis-[Ru(bpy)₂(MeCN)₂]²⁺ (5). Crystal structures of N-(4-chlorophenyl) imidazo[1,5a] pyridine (4b) and cis-[Ru(bpy)₂(MeCN)₂](ClO₄)₂ (5) are also reported.     

Chemistry of Ruthenium Polypyridine Complexes: IX. Nitro-Nitrosyl Equilibrium in cis-[Ru(2,2'-bpy)2(L)NO2]+ Complexes

Ruthenium(II) bisbipyridyl complexes cis-[Ru(bpy)₂(L)NO₂](BF₄) (bpy is 2,2'-bipyridyl) with 4-substituted pyridine ligands L = 4-(Y)py (Y = NH₂, Me, Ph, and CN) were obtained. The equilibrium constants of the reversible nitro-nitrosyl transition [Ru(bpy)₂(L)NO₂]⁺ + 2H⁺ [Ru(bpy)₂(L)NO]^{3 +} + H₂O were measured in solutions with pH 1.5-8.5 (ionic strength 0.4). The constants correlate with the protonation constants of free ligands 4-(Y)py.     

Synthesis, characterization, and reactivity of [Ru(bpy)(CH3CN)3(NO2)]PF6, a synthon for [Ru(bpy)(L3)NO2] complexes

We report a high yield, two-step synthesis of fac-[Ru(bpy)(CH3CN)3NO2]PF6 from the known complex [(p-cym)Ru(bpy)Cl]PF6 (p-cym = eta(6)-p-cymene). [(p-cym)Ru(bpy)NO2]PF6 is prepared by reacting [(p-cymene)Ru(bpy)Cl]PF6 with AgNO3/KNO2 or AgNO2. The 15NO2 analogue is prepared using K15NO2. Displacement of p-cymene from [(p-cym)Ru(bpy)NO2]PF6 by acetonitrile gives [Ru(bpy)(CH3CN)3NO2]PF6. The new complexes [(p-cym)Ru(bpy)NO2]PF6 and fac-[Ru(bpy)(CH3CN)3NO2]PF6 have been fully characterized by 1H and 15N NMR, IR, elemental analysis, and single-crystal structure determination. Reaction of [Ru(bpy)(CH3CN)3NO2]PF6 with the appropriate ligands gives the new complexes [Ru(bpy)(Tp)NO2] (Tp = HB(pz)3-, pz = 1-pyrazolyl), [Ru(bpy)(Tpm)NO2]PF6 (Tpm = HC(pz)3), and the previously prepared [Ru(bpy)(trpy)NO2]PF6 (trpy = 2,2',6',2' '-terpyridine). Reaction of the nitro complexes with HPF6 gives the new nitrosyl complexes [Ru(bpy)TpNO][PF6]2 and [Ru(bpy)(Tpm)NO][PF6]3. All complexes were prepared with 15N-labeled nitro or nitrosyl groups. The nitro and nitrosyl complexes were characterized by 1H and 15N NMR and IR spectroscopy, elemental analysis, cyclic voltammetry, and single-crystal structure determination for [Ru(bpy)TpNO][PF6]2. For the nitro complexes, a linear correlation is observed between the nitro 15N NMR chemical shift and 1/nu(asym), where nu(asym) is the asymmetric stretching frequency of the nitro group.     

Structural studies on supramolecular adducts of cyclodextrins with the complex [Ru([9]aneS3)(bpy)Cl]Cl

The complex [Ru([9]aneS₃)(bpy)Cl]Cl (bpy = 2,2′-bipyridine) was immobilised in plain β-cyclodextrin (β-CD) and permethylated β-CD (TRIMEB) to yield two adducts with a 1:1 host:guest stoichiometry. The adducts were studied by powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), ¹³C{¹H} CP/MAS NMR and vibrational spectroscopy (FT-IR and Raman). Results support the formation of stable supramolecular adducts with a proposed geometry in which the coordinated bypiridine fragment of the guest is partially included in the host cavities, and the bulky [9]aneS₃ fragment protrudes out to the interstitial spaces. A packing mode is proposed for [Ru([9]aneS₃)(bpy)Cl]Cl · TRIMEB, obtained by Monte Carlo optimisation of the XRD data. TRIMEB molecules are stacked in tilted channels, with the voluminous part of the guest molecules in the inter-channel space. The behaviour of [Ru([9]aneS₃])(bpy)Cl]Cl upon CD encapsulation and the chloride ligand hydrolysis process in solution for all compounds were studied in detail by Raman spectroscopy.     

Electrolyte Effects on Charge Transport Behavior of [Os(bpy)2(PVP)10Cl]Cl and [Ru(bpy)2(PVP)10Cl]Cl Redox Polymers in Ultra‐Thin Films of Polyions

Metallopolymer films have important applications in electrochemical catalysis. The alternate electrostatic layer‐by‐layer method was used to assemble films of [Ru(bpy)₂(PVP)₁₀Cl]Cl (denoted as ClRu‐PVP) and [Os(bpy)₂(PVP)₁₀Cl]Cl (ClOs‐PVP) metallopolymers onto pyrolytic graphite electrodes. Film thickness estimated by quartz crystal microbalance was 6–8 nm. The effects of pH, electrolyte species and concentration on the electrochemical properties of these electroactive polymers were studied using cyclic voltammetry (CV). Behavior in various electrolytes was compared. Also the mass changes within the ultra‐thin film during redox of Os^2+/3+ were characterized by in situ electrochemical quartz crystal microbalance (EQCM). The results indicate rapid reversible electron transfer, and show that both ClRu‐PVP and ClOs‐PVP have compact surface structures while ClOs‐PVP is a little denser than ClRu‐PVP. Although hydrogen ions do not participate in the chemical reaction of either film, the movement of Na⁺ cation and water accompanies the redox process of ClOs‐PVP films.     

Synthesis,characterization, DNA-binding and DNA-photocleavage studies of [Ru(bpy)2(BPIP)] and [Ru(phen)2(BPIP)] (BPIP = 2-(4′-biphenyl)imidazo[4,5-f][1,10]phenanthroline)

New ligand 2-(4′-biphenyl)imidazo[4,5-f][1,10]phenanthroline (BPIP) and its complexes [Ru(bpy)₂(BPIP)]²⁺ (1) (bpy = 2,2′-bipyridine) and [Ru(phen)₂(BPIP)]²⁺ (2) (phen = 1,10-phenanthroline) have been synthesized and characterized by mass spectroscopy, ¹H NMR and cyclic voltammetry. The interaction of two Ru(II) complexes with calf thymus DNA (CT-DNA) was investigated by spectroscopic and viscosity measurements. Results indicate that both complexes bind to DNA via an intercalative mode and the DNA-binding affinity of complex 2 is much greater than that of complex 1. Furthermore, when irradiated at 365 nm, both complexes have also been found to promote the photocleavage of plasmid pBR 322 DNA.     

Synthesis of heteroleptic bis(diimine)carbonylchlororuthenium(II) complexes from photodecarbonylated precursors

The reactions of bidentate diimine ligands (L2) with binuclear [Ru(L1)(CO)Cl2]2 complexes [L1 not equal to L2 = 2,2'-bipyridine (bpy), 4,4'-dimethyl-2,2'-bipyridine (4,4'-Me2bpy), 5,5'-dimethyl-2,2'-bipyridine (5,5'-Me2bpy), 1,10-phenanthroline (phen), 4,7-dimethyl-1,10-phenanthroline (4,7-Me2phen), 5,6-dimethyl-1,10-phenanthroline (5,6-Me2phen), di(2-pyridyl)ketone (dpk), di(2-pyridyl)amine (dpa)] result in cleavage of the dichloride bridge and the formation of cationic [Ru(L1)(L2)(CO)Cl]+ complexes. In addition to spectroscopic characterization, the structures of the [Ru(bpy)(phen)(CO)Cl]+, [Ru(4,4'-Me2bpy)(5,6-Me2phen)(CO)Cl]+ (as two polymorphs), [Ru(4,4'-Me2bpy)(4,7-Me2phen)(CO)Cl]+, [Ru(bpy)(dpa)(CO)Cl]+, [Ru(5,5'-Me2bpy)(dpa)(CO)Cl]+, [Ru(bpy)(dpk)(CO)Cl]+, and [Ru(4,4'-Me2bpy)(dpk)(CO)Cl]+ cations were confirmed by single crystal X-ray diffraction studies. In each case, the structurally characterized complex had the carbonyl ligand trans to a nitrogen from the incoming diimine ligand, these complexes corresponding to the main isomers isolated from the reaction mixtures. The synthesis of [Ru(4,4'-Me2bpy)(5,6-Me2bpy)(CO)(NO3)]+ from [Ru(4,4'-Me2bpy)(5,6-Me2bpy)(CO)Cl]+ and AgNO3 demonstrates that exchange of the chloro ligand can be achieved.     

Synthesis,Characterization, and DNA Interaction Studies of the Ruthenium(II) Complexes [Ru(bpy)2(ipbp)]2+ and [Ru(ipbp)(phen)2]2+ (ipbp=3‐(1H‐Imidazo[4,5‐f][1,10]phenanthrolin‐2‐yl)‐4H‐1‐benzopyran‐2‐one; bpy=2,2′‐Bipyridine; phen=1,10‐Phenanthroline)

A novel ligand 3‐(1H‐imidazo[4,5‐f][1,10]phenanthrolin‐2‐yl)‐4H‐1‐benzopyran‐4‐one (ipbp) and its ruthenium(II) complexes [Ru(bpy)₂(ipbp)]²⁺ ( 1 ) and [Ru(ipbp)(phen)₂]²⁺ ( 2 ) (bpy=2,2′‐bipyridine, phen=1,10‐phenanthroline) were synthesized and characterized by elemental analysis and mass, ¹H‐NMR, and electronic‐absorption spectroscopy. The electrochemical behavior of the complexes was studied by cyclic voltammetry. The DNA‐binding behavior of the complexes was investigated by spectroscopic methods and viscosity measurements. The results indicate that complexes 1 and 2 bind with calf‐thymus DNA in an intercalative mode. In addition, 1 and 2 promote cleavage of plasmid pBR 322 DNA from the supercoil form I to the open circular form II upon irradiation.     

Synthesis,characterization and DNA binding studies of ruthenium(II) complexes: [Ru(bpy)<Subscript>2</Subscript>(dtmi)]<Superscript>2+</Superscript> and [Ru(bpy)<Subscript>2</Subscript>(dtni)]<Superscript>2+</Superscript>

Two new ruthenium(II) polypyridyl complexes (1) (dtmi = 3-(pyrazin-2-yl)-as-triazino[5,6-f]-5-methoxylisatin) and (2) (dtni = 3-(pyrazin-2-yl)-as-triazino[5,6-f]-5-nitroisatin) have been synthesized and characterized by elemental analysis, FAB-MS, ES-MS and ¹H-n.m.r. The DNA-binding patterns of complexes were investigated by spectroscopic titration, viscosity measurements and thermal denaturation. The results indicate that the complexes (1) and (2) interact with calf thymus DNA (CT-DNA) by intercalative mode. Due to the withdrawing electronic substitutent in the intercalative ligand, ptni, the DNA-binding affinity of the complexes (2) is larger than that complex (1) does.     

Formation and reactivity of the Os(IV)-azidoimido complex, PPN[Os(IV)(bpy)(Cl)(3)(N(4))

Reactions between the Os(VI)-nitrido complexes, [OsVI(L2)(Cl)3(N)] (L2 = 2,2'-bipyridine (bpy) ([1]), 4,4'-dimethyl-2,2'-bipyridine (Me2bpy), 1,10-phenanthroline (phen), and 4,7-diphenyl-1,10-phenanthroline (Ph2phen)), and bis-(triphenylphosphoranylidene)ammonium azide (PPNN3) in dry CH3CN at 60 degrees C under N2 give the corresponding Os(IV)-azidoimido complexes, [OsIV(L2)(Cl)3(NN3)]- (L2 = bpy = [2]-, L2 = Me2bpy = [3]-, L2 = phen = [4]-, and L2 = Ph2phen = [5]-) as their PPN+ salts. The formulation of the N42- ligand has been substantiated by 15N-labeling, IR, and 15N NMR measurements. Hydroxylation of [2]- at Nalpha with O<--NMe3.3H2O occurs to give the Os(IV)-azidohydroxoamido complex, [OsIV(bpy)(Cl)3(N(OH)N3)] ([6]), which, when deprotonated, undergoes dinitrogen elimination to give the Os(II)-dinitrogen oxide complex, [OsII(bpy)(Cl)3(N2O)]- ([7]-). They are the first well-characterized examples of each kind of complex for Os.     

1-(2′-Pyridylazo)-2-naphtholate complexes of ruthenium: Synthesis,characterization, and DNA binding properties

Reaction of 1-(2′-pyridylazo)-2-naphthol (Hpan) with [Ru(dmso)₄Cl₂] (dmso = dimethylsulfoxide), [Ru(trpy)Cl₃] (trpy = 2,2′,2″-terpyridine), [Ru(bpy)Cl₃] (bpy = 2,2′-bipyridine) and [Ru(PPh₃)₃Cl₂] in refluxing ethanol in the presence of a base (NEt₃) affords, respectively, the [Ru(pan)₂], [Ru(trpy)(pan)]⁺ (isolated as perchlorate salt), [Ru(bpy)(pan)Cl] and [Ru(PPh₃)₂(pan)Cl] complexes. Structures of these four complexes have been determined by X-ray crystallography. In each of these complexes, the pan ligand is coordinated to the metal center as a monoanionic tridentate N,N,O-donor. Reaction of the [Ru(bpy)(pan)Cl] complex with pyridine (py) and 4-picoline (pic) in the presence of silver ion has yielded the [Ru(bpy)(pan)(py)]⁺ and [Ru(bpy)(pan)(pic)]⁺ complexes (isolated as perchlorate salts), respectively. All the complexes are diamagnetic (low-spin d⁶, S = 0) and show characteristic ¹H NMR signals and intense MLCT transitions in the visible region. Cyclic voltammetry on all the complexes shows a Ru(II)–Ru(III) oxidation on the positive side of SCE. Except in the [Ru(pan)₂] complex, a second oxidative response has been observed in the other five complexes. Reductions of the coordinated ligands have also been observed on the negative side of SCE. The [Ru(trpy)(pan)]ClO₄, [Ru(bpy)(pan)(py)]ClO₄ and [Ru(bpy)(pan)(pic)]ClO₄ complexes have been observed to bind to DNA, but they have not been able to cleave super-coiled DNA on UV irradiation.     

Synthesis and crystal structures of ruthenium(II) complexes with polypyridyl: [Ru(bpy)2(AFO)](ClO4)2 · H2O and [Ru(dmp)2 (AFO)](ClO4)2 · 1/2DMF · 1/2MeCN

Two ruthenium(II) complexes with polypyridyl ligands, [Ru(bpy)₂(AFO)](ClO₄)₂ · H₂O (1) and [Ru(dmp)₂ (AFO)](ClO₄)₂ · 1/2DMF · 1/2MeCN (2) (bpy = 2,2′-bipyridine; dmp = 2,9-dimethyl-1,10-phenanthroline; AFO = 4,5-diazafluoren-9-one; DMF = N,N-dimethylformamide), were synthesized and characterized by elemental analyses, i.r. and u.v.-vis. spectra. The structures of the two complexes were determined by single crystal X-ray diffraction techniques. To relieve ligand interaction, the coordination sphere is distorted so as to form specific angles (δ) between the polypyridyl ligand planes and coordination planes (N-Ru-N). This revised version was published online in June 2006 with corrections to the Cover Date.     

Ru(bpy) 3 2+ sensitized photopolymerization ofN,N′-methylene-bisacrylamide

Photochemical polymerization ofN,N′-methylenebisacrylamide (MBA) initiated by the dye-reducing agent rhodamine-B-allylthiourea (ATU) system is enhanced by the addition of small amounts oftris(2,2′-bipyridine)-ruthenium(II), Ru(bpy) ₃ ²⁺ , a result attributed to the efficient formation of chain-initiating allylthiourea radicals in the presence of Ru(bpy) ₃ ²⁺ ions. The rate of polymerization was found to be proportional to [Ru(bpy) ₃ ²⁺ ]^0.5, [rhodamine-B]^0.5, [ATU]^0.5 and [MBA]^1.0. A probable mechanism consistent with the observed results is proposed and discussed. TMC 2391     

钌卟啉[Ru(bpy)2(MPyTPP)Cl]+与DNA作用的研究

钌卟啉(ruthenated porphyrin)是通过卟啉环上的配位基团与多吡啶钌配位而得到的一类具有丰富的光谱和化学活性的大分子配合物[1～5]. 目前, 对钌卟啉的研究大都集中在其氧化还原、电化学以及催化氧化反应活性和超分子自组装等方面, 而对钌卟啉生物功能方面的研究则鲜为报道[6].     

Effects of substituent on the DNA-binding of ruthenium(II) complexes containing asymmetric tridentate intercalative ligands

Three novel unsymmetric tridentate ligands, namely, ptmi (ptmi = 3-(1,10-phenanthroline-2-yl)-as-triazino[5,6-f]-5-methoxyisatin), pti (pti = 3-(1,10-phenanthroline-2-yl)-as-triazino-[5,6-f]isatin), ptni (ptni = 3-(1,10-phenanthroline-2-yl)-as-triazino[5,6-f]-5-nitroisatin), and their complexes [Ru(tpy)(ptmi)](ClO₄)₂ (tpy = 2,2′:6′,2″-terpyridine) (1), [Ru(tpy)(pti)](ClO₄)₂ (2), and [Ru(tpy)(ptni)](ClO₄)₂ (3) were prepared and characterized by elemental analysis, ¹H NMR, ES–MS. The electrochemical behaviors were studied by cyclic voltammetry. The DNA-binding properties of these complexes were investigated by the spectroscopic method, viscosity measurements, and thermal denaturation. Theoretical studies on these complexes were also performed with the density functional theory (DFT) method. The experimental results showed that these complexes bind to calf thymus (CT-DNA) in an intercalative mode. The order of DNA-binding affinities (A) of these complexes is A(1) < A(2) < A(3). The trend in the DNA-binding affinities of this series of complexes can be reasonably explained by the DFT calculations.     

Chemistry of Polypyridine Ruthenium Complexes: VII. Electronic Structure and Photochemistry of cis-[Ru(2,2'-bpy)2(L)(Cl)]+ Complexes

The electronic absorption spectra and photochemical behavior of the complexes of cis-[Ru(bpy)₂ · (L)(Cl)]⁺ (bpy is 2,2'-bipyridyl) with pyridine (L = py) and 4-substituted pyridines [L = methyl-, amino-, and cyanopyridine, and 4,4'-bipyridyl (bipy)]. Photoirradiation of acetonitrile solutions of the complexes results in substitution of ligand L by a solvent molecule. A correlation was revealed between the photolysis quantum yield and the coordination-induced ligand L-to-metal charge transfer.     

Photochemistry of fac‐[Re(bpy)(CO)3Cl]

The photochemistry of fac‐[Re(bpy)(CO)₃Cl] ( 1 a ; bpy=2,2′‐bipyridine) initiated by irradiation using <330 nm light has been investigated. Isomerization proceeded in THF to give the corresponding mer‐isomer 1 b . However, in the presence of a small amount of MeCN, the main product was the CO‐ligand‐substituted complex (OC‐6‐24)‐[Re(bpy)(CO)₂Cl(MeCN)] ( 2 c ; bpy=2,2′‐bipyridine). In MeCN, two isomers, 2 c and its (OC‐6‐34) form ( 2 a ), were produced. Only 2 c thermally isomerized to produce the (OC‐6‐44) form 2 b . A detailed investigation led to the conclusion that both 1 b and 2 c are produced by a dissociative mechanism, whereas 2 a forms by an associative mechanism. A comparison of the ultrafast transient UV‐visible absorption, emission, and IR spectra of 1 a acquired by excitation using higher‐energy light (e.g., 270 nm) and lower‐energy light (e.g., 400 nm) gave detailed information about the excited states, intermediates, and kinetics of the photochemical reactions and photophysical processes of 1 a . Irradiation of 1 a using the higher‐energy light resulted in the generation of the higher singlet excited state with τ≤25 fs, from which intersystem crossing proceeded to give the higher triplet state (³HES( 1 )). In THF, ³HES( 1 ) was competitively converted to both the triplet ligand field (³LF) and metal‐to‐ligand charge transfer (³M LCT) with lifetimes of 200 fs, in which the former is a reactive state that converts to [Re(bpy)(CO)₂Cl(thf)]⁺ ( 1 c ) within 10 ps by means of a dissociative mechanism. Re‐coordination of CO to 1 c gives both 1 a and 1 b . In MeCN, irradiation of 1 a by using high‐energy light gives the coordinatively unsaturated complex, which rapidly converted to 2 c . A seven‐coordinate complex is also produced within several hundred femtoseconds, which is converted to 2 a within several hundred picoseconds.     

Syntheses, structures, spectroscopic, electrochemical properties and DFT calculation of Ru(II)–thioarylazoimidazole complexes

The reaction of 1-alkyl-2-{(o-thioalkyl)phenylazo}imidazoles (SRaaiNR) (2a/2b) with Ru(II) has synthesized [Ru(SRaaiNR)₂](ClO₄)₂ (3a/3b) in 2-methoxyethanol. The reaction in methanol, however, has synthesized [Ru(SRaaiNR)(SRaaiNR)Cl](ClO₄) (4a/4b). The solid phase reaction of SRaaiNR and RuCl₃ on silica gel surface upon microwave irradiation has synthesized [Ru(SRaaiNR)(SaaiNR)](PF₆) (5a/5b) [SRaaiNR represents tridentate N,N′,S-chelator; SRaaiNR is N,N′-bidentate chelator where S does not coordinate and SaaiNR refers N,N′,S-chelator where S refers to thiolato binding]. The structural characterization of [Ru(SEtaaiNEt)(SEtaaiNEt)Cl](ClO₄) (4b) and [Ru(SEtaaiNEt)(SaaiNEt)](PF₆) (5b) has been confirmed by single crystal X-ray diffraction study. The IR, UV–Vis, and ¹H NMR spectral data also support the stereochemistry of the complexes. The complexes show metal oxidation, Ru(III)/Ru(II), and ligand reductions (azo/azo⁻, azo⁻/azo). The molecular orbital diagram has been drawn by density functional theory (DFT) calculation. Normal mode of analysis has been performed to correlate calculated and experimental frequencies of representative complexes. The electronic movement and assignment of electronic spectra have been carried out by TDDFT calculation both in gas and acetonitrile phase.