Conductimetric Studies of Charge Transfer Complexes of p‐Chloranil with Some Alicyclic Amines in Polar Media

The stoichiometry of charge‐transfer complexes which ionise in polar media has been studied by conductimetric titration technique in the systems morpholine‐p‐chloranil (CA), piperidine‐CA and pyrrolidine‐CA in three different polar solvents namely N,N‐dimethylformamide, acetonitrile and dimethylsulfoxide at different temperatures of 10, 15, 18, 20, 25 and 30 °C. The stoichiometric ratios of these complexes were found to vary from 1:1 to 1:4 (acceptor: donor) depending on the system, temperature and solvent used. The ασ_M‐values of these complexes have been reported. The effect of solvents, temperatures and types of electron donors on the σ_P‐values has been examined.     

Two new isostructural mercury(II) complexes involving the N‐heterocyclic 1‐[(benzotriazol‐1‐yl)methyl]‐1H‐1,3‐imidazole ligand: syntheses,structures and properties

The unsymmetrical N‐heterocyclic ligand 1‐[(benzotriazol‐1‐yl)methyl]‐1H‐1,3‐imidazole (bmi) has three potential N‐atom donors and can act in monodentate or bridging coordination modes in the construction of complexes. In addition, the bmi ligand can adopt different coordination conformations, resulting in complexes with different structures due to the presence of the flexible methylene spacer. Two new complexes, namely bis{1‐[(benzotriazol‐1‐yl)methyl]‐1H‐1,3‐imidazole‐κN ³}dibromidomercury(II), [HgBr₂(C₁₀H₉N₅)₂], and bis{1‐[(benzotriazol‐1‐yl)methyl]‐1H‐1,3‐imidazole‐κN ³}diiodidomercury(II), [HgI₂(C₁₀H₉N₅)₂], have been synthesized through the self‐assembly of bmi with HgBr₂ or HgI₂. Single‐crystal X‐ray diffraction shows that both complexes are mononuclear structures, in which the bmi ligands coordinate to the Hg^II ions in monodentate modes. In the solid state, both complexes display three‐dimensional networks formed by a combination of hydrogen bonds and π–π interactions. The IR spectra and PXRD patterns of both complexes have also been recorded.     

Organometallic Lewis Acids,Part LXI. Cationic Pentacarbonylrhenium Complexes [(OC)5Re‐L]+BF4– with Aromatic Amines (L) as Ligands

Aromatic amines (aniline and derivatives) react with (OC)₅ReFBF₃ to give the cationic complexes [(OC)₅Re‐L]⁺ as BF₄^– salts under mild conditions and in high yields. Dinuclear, dicationic complexes are formed with o‐ and p‐phenylenediamine. Substitution of tetrafluoroborate by the N‐donors is preferred before attack at a carbonyl ligand.     

Reaktionen von Pentafulven‐Komplexen des Titans mit Nitrilen und iso‐Nitrilen — Synthese und Isomerisierungen von σ, π‐Chelatkomplexen mit Cp∼N‐Liganden

Reactions of Pentafulvene Complexes of Titanium with Nitriles and iso‐Nitriles — Synthesis and Isomerizations of σ, π‐Chelat Complexes with Cp∼N‐Ligands The reactions of fulvene complexes Cp*Ti{η⁶—C₅H₄=C(R)(R')}Cl (R = H, R' = tBu ( 1 ); R = Me, R' = iPr ( 4 )) with nitriles and iso‐nitriles, leading to σ, π‐chelat complexes with Cp∼N‐ligands, have been examined and the formed products characterized. Whereas in the reactions of 1 and 4 , respectively, with nitriles a 1, 2‐mono‐insertion of the CN‐group in the Ti—C(R)(R') (Fv) bond is observed, the reaction with iso‐nitrils leads to the insertion of two molecules iso‐nitrile. The nitrile insertion product of 1 is characterized by an imine‐enamine tautomerization. Whereas the primary built meta stable imine species ( 3 ) was only identified by NMR measurements in solution, the enamine tautomer ( 2 ) crystallized from n‐hexane, so that the crystal structure could be determined. The primary formed iminoacyl complex ( 7 ) rearranges due to the electrophilicity of the titanium centre and builds a Ti—N bond with significant N(pπ) → Ti(dπ) bonding character.     

Transient Absorption Spectral characterization of Electron Transfer between Fullerenes（C60／C70）and N,N,N’，N’—Tetra（p—methylphenyl）—4,4’—diamino—1,1’—diphenyl Sulphide（TPDAS）

In search of new systems with a photoexcited redox pair which exhibits a strong and stable photoinduced absorption band to understand the photophyscial and photochemical properties of electron transfer between fullernes (C60/C70) and organic donor[N,N,N’，N’-tetra(p-methylphenyl)-4,4’-diamino-1,1’-diphenyl sulphide(TPDAS)],we studied characteristic absorption spectra in the near-IR region obtained from 532nm nanosecond laser flash photolysis of a mixture of the fullerenes (C60/C70) and TPDAS in polar solvents.When fullerenes (C60/C70)were photoexcithed,the rise of the radical anion of fullerenes (C60/C70)with the rapid decay of their excited triplet states were observed in benzonitrile.It can be deduced that the electron transfer reaction does take place from TPDAS to excithed triplet state of rullerens(C60/C70).The rate consants(ket)and quantum yiekls(φet) of this process have been also evaluated.     

Charge‐transfer character of halogen bonding: Molecular structures and electronic spectroscopy of carbon tetrabromide and bromoform complexes with organic σ‐ and π‐donors

Carbon tetrabromide and bromoform are employed as prototypical electron acceptors to demonstrate the charge‐transfer nature of various intermolecular complexes with three different structural types of electron donors represented by (1) halide and pseudohalide anions, (2) aromatic (π‐bonding) hydrocarbons, and (3) aromatics with (n‐bonding) oxygen or nitrogen centers. UV–Vis spectroscopy identifies the electronic transition inherent to such [1:1] complexes; and their Mulliken correlation with the donor/acceptor strength verifies the relevant charge‐transfer character. X‐ray crystallography of CBr₄/HCBr₃ complexes with different types of donors establishes the principal structural features of halogen bonding. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:449–459, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20264     

Synthesis and structures of photoactive manganese–carbonyl complexes derived from 2‐(pyridin‐2‐yl)‐1,3‐benzothiazole and 2‐(quinolin‐2‐yl)‐1,3‐benzothiazole

PhotoCORMs (photo‐active CO‐releasing molecules) have emerged as a class of CO donors where the CO release process can be triggered upon illumination with light of appropriate wavelength. We have recently reported an Mn‐based photoCORM, namely [MnBr(pbt)(CO)₃] [pbt is 2‐(pyridin‐2‐yl)‐1,3‐benzothiazole], where the CO release event can be tracked within cellular milieu by virtue of the emergence of strong blue fluorescence. In pursuit of developing more such trackable photoCORMs, we report herein the syntheses and structural characterization of two Mn^I–carbonyl complexes, namely fac‐tricarbonylchlorido[2‐(pyridin‐2‐yl)‐1,3‐benzothiazole‐κ²N ,N ′]manganese(I), [MnCl(C₁₂H₈N₂S)(CO)₃], (1), and fac‐tricarbonylchlorido[2‐(quinolin‐2‐yl)‐1,3‐benzothiazole‐κ²N ,N ′]manganese(I), [MnCl(C₁₆H₁₀N₂S)(CO)₃], (2). In both complexes, the Mn^I center resides in a distorted octahedral coordination environment. Weak intermolecular C—H…Cl contacts in complex (1) and Cl…S contacts in complex (2) consolidate their extended structures. These complexes also exhibit CO release upon exposure to low‐power broadband visible light. The apparent CO release rates for the two complexes have been measured to compare their CO donating capacity. The fluorogenic 2‐(pyridin‐2‐yl)‐1,3‐benzothiazole and 2‐(quinolin‐2‐yl)‐1,3‐benzothiazole ligands provide a convenient way to track the CO release event through the `turn‐ON' fluorescence which results upon de‐ligation of the ligands from their respective metal centers following CO photorelease.     

Spectroscopic studies of charge transfer complexes of meso‐tetra‐p‐tolylporphyrin and its zinc complex with some aromatic nitro acceptors in different organic solvents

The charge transfer complex (CTC) formation of 5,10,15,20‐tetra(p‐tolyl)porphyrin (TTP) and zinc 5,10,15,20‐tetra(p‐tolyl)porphyrin with some aromatic nitro acceptors such as 2,4,6‐trinitrophenol (picric acid), 3,5‐dinitrosalicylic acid, 3,5‐dinitrobenzoic acid (DNB) and 2,4‐dinitrophenol (DNP) was studied spectrophotometrically in different organic solvents at different temperatures. The spectrophotometric titration, Job's and straight line methods indicated the formation of 1:1 CTCs. The values of the equilibrium constant (K_CT) and molar extinction coefficient (ε_CT) were calculated for each complex. The ionization potential of the donors and the dissociation energy of the charge transfer excited state for the CTC in different solvents was also determined and was found to be constant. The spectroscopic and thermodynamic properties were observed to be sensitive to the electron affinity of the acceptors and the nature of the solvent. No CT band was observed between Zn‐TTP as donor and DNP or DNB as acceptors in various organic solvents at different temperature. Bimolecular reactions between singlet excited TTP (¹TTP*) and the acceptors were investigated in solvents with various polarities. A new emission band was observed. The fluorescence intensity of the donor band decreased with increasing the concentration of the acceptor accompanied by an increase in the intensity of the new emission. The new emission of the CTCs can be interpreted as a CT excited complex (exciplex). Copyright © 2007 John Wiley & Sons, Ltd.     

Luminescent Amphiphilic 2,6‐Bis(1‐alkylpyrazol‐3‐yl)pyridyl Platinum(II) Complexes: Synthesis,Characterization, Electrochemical,Photophysical, and Langmuir–Blodgett Film Formation Studies

Two series of novel platinum(II) 2,6‐bis(1‐alkylpyrazol‐3‐yl)pyridyl (N5Cn) complexes, [Pt(N5Cn)Cl][X] ( 1 – 9 ) and [Pt(N5Cn)(C?CR)][X] ( 10 – 13 ) (X=trifluoromethanesulfonate (OTf) or PF₆; R=C₆H₅, C₆H₄‐p‐CF₃ and C₆H₄‐p‐N(C₆H₅)₂), with various chain lengths of the alkyl groups on the nitrogen atom of the pyrazolyl units have been successfully synthesized and characterized. Their electrochemical and photophysical properties have been studied. Some of their molecular structures have also been determined by X‐ray crystallography. Two amphiphilic platinum(II) 2,6‐bis(1‐tetradecylpyrazol‐3‐yl)pyridyl (N5C14) complexes, [Pt(N5C14)Cl]PF₆ ( 7 ) and [Pt(N5C14)(C?CC₆H₅)]PF₆ ( 13 ), were found to form stable and reproducible Langmuir–Blodgett (LB) films at the air–water interface. The characterization of such LB films has been investigated by the study of their surface pressure–area (π–A) isotherms, UV/Vis spectroscopy, XRD, X‐ray photoelectron spectroscopy (XPS), FTIR, and polarized IR spectroscopy. The luminescence property of 13 in LB films has also been studied.     

Intrinsic Acid–Base Properties of a Hexa‐2′‐deoxynucleoside Pentaphosphate,d(ApGpGpCpCpT): Neighboring Effects and Isomeric Equilibria

The intrinsic acid‐base properties of the hexa‐2′‐deoxynucleoside pentaphosphate, d(ApGpGpCpCpT) [=(A1?G2?G3?C4?C5?T6)=(HNPP)^5?] have been determined by ¹H NMR shift experiments. The pK_a values of the individual sites of the adenosine (A), guanosine (G), cytidine (C), and thymidine (T) residues were measured in water under single‐strand conditions (i.e., 10 % D₂O, 47 °C, I=0.1 M , NaClO₄). These results quantify the release of H⁺ from the two (N7)H⁺ (G?G), the two (N3)H⁺ (C?C), and the (N1)H⁺ (A) units, as well as from the two (N1)H (G?G) and the (N3)H (T) sites. Based on measurements with 2′‐deoxynucleosides at 25 °C and 47 °C, they were transferred to pK_a values valid in water at 25 °C and I=0.1 M . Intramolecular stacks between the nucleobases A1 and G2 as well as most likely also between G2 and G3 are formed. For HNPP three pK_a clusters occur, that is those encompassing the pK_a values of 2.44, 2.97, and 3.71 of G2(N7)H⁺, G3(N7)H⁺, and A1(N1)H⁺, respectively, with overlapping buffer regions. The tautomer populations were estimated, giving for the release of a single proton from five‐fold protonated H₅(HNPP)^±, the tautomers (G2)N7, (G3)N7, and (A1)N1 with formation degrees of about 74, 22, and 4 %, respectively. Tautomer distributions reveal pathways for proton‐donating as well as for proton‐accepting reactions both being expected to be fast and to occur practically at no “cost”. The eight pK_a values for H₅(HNPP)^± are compared with data for nucleosides and nucleotides, revealing that the nucleoside residues are in part affected very differently by their neighbors. In addition, the intrinsic acidity constants for the RNA derivative r(A1?G2?G3? C4?C5?U6), where U=uridine, were calculated. Finally, the effect of metal ions on the pK_a values of nucleobase sites is briefly discussed because in this way deprotonation reactions can easily be shifted to the physiological pH range.     

C—H…Cl Hydrogen Bond and π-π Interaction Based Two 3D Supramolecular Architectures of Cu(II) and Co(II) Complexes with Chiral 1,2-Bis(benzimidazol-2-yl) ethane Ligand Containing 2D Grids

合成了两个新的配合物CuLCl₂•2EtOH(1) 和CoLCl₂ (2) [L是( S , S )－1,2－二N－甲基苯并咪唑－1,2－二甲氧基－乙烷],并通过单晶X衍射确定它们的结构。配合物1中,L作为三齿[N, N, O]配体,而配合物2 中,L作为二齿[N, N]配体。这两个配合物共同的结构特点都是通过分子内氢键形成2维的格子结构,然后通过分子间的C－H···Cl型氢键和π–π堆积作用形成3维结构。     

Kinetic Studies of Oxidative Addition Reaction of Arylplatinum(II) Complex Containing 4,4′‐Bipyridine and Calculation of Activation Parameters

New complexes of arylplatinum(II) and arylplatinum(IV) containing a bridging ligand, 4,4′‐bipyridine, were synthesized by the reaction of starting material of platinum(II) including para‐tolyl groups,[(p‐MeC₆H₄)₂Pt(SMe₂)₂], with the 4,4′‐bipyridine ligand in 1:1 molar stoichiometry. In the synthesized complexes, the ligand was bonded to the platinum center through the nitrogen donor atoms. To investigate the kinetic reaction of the platinum(II) complex with iodomethane (CH₃‐I) as a reagent, the oxidative addition reaction of this reagent with Pt(II) was performed in dichloromethane and a Pt(IV) complex with the octahedral geometry was formed. The synthesized complexes have been characterized by different spectroscopic methods such as FT‐IR, ¹H NMR, UV–vis, and elemental analysis. Moreover, the conductivity measurements showed nonelectrolyte characteristics for these complexes. The obtained data showed that the complexes have 1:1 metal‐to‐ligand molar ratio. Also, the oxidative addition reaction of CH₃I with the arylplatinum(II) complex at different temperatures was used for obtaining kinetic parameters such as rate constants, activation energy, entropy, and enthalpy of activation using the Microsoft Excel solver. From the acquired data, an S_N2 mechanism was suggested for the oxidative addition reaction.     

Mononuclear Carbene Dithiolate [Ni(NHX)(′S2C ′)] Complexes with HNX = HNPiPr3 or HNSPh2 Coligands (′S2C ′ 2– = 1,3‐ImidazolidinylN,N′‐bis(2‐benzenethiolate)(2–))

Cleavage reactions of the dinuclear [{Ni(′S₂C ′)}₂] · DMF (′S₂C ′ ^2– = 1,3‐imidazolidinyl‐N,N′‐bis(2‐benzenethiolate)(2–)) with HNPiPr₃ or HNSPh₂ yielded the mononuclear complexes [Ni(NHPiPr₃)(′S₂C ′)] ( 1 ) and [Ni(NHSPh₂)(′S₂C ′)] ( 2 ) which have been completely characterized. The nickel‐carbene‐dithiolate [Ni(′S₂C ′)] moiety is one of the very rare complex fragments that are able to coordinate both HNPR₃ or HNSR₂. IR spectra and X‐ray structure determinations show that 1 and 2 exhibit intramolecular N–H…S(thiolate) hydrogen bonds. Geometric parameters and NMR spectroscopic data of 1 and 2 are compatible with N–X single bonds and ylidic structures of the HNPiPr₃ and HNSPh₂ ligands. Comparison of Ni–N distances in diamagnetic and paramagnetic [Ni(NHSPh₂)] complexes was rendered possible through the X‐ray structure determination of the homoleptic [Ni(NHSPh₂)₆]Cl₂ ( 3 ) which formed as minor by‐product in the synthesis of 2 .     

Rigid‐rod polyamides and polyimides prepared from 4,3″‐diamino‐2′,6′‐di(2‐naphthyl)‐p‐terphenyl and 2′,6′,3‴,5‴‐tetra(2‐naphthyl)‐4,4″‐diamino‐p‐quinquephenyl

A series of rigid‐rod polyamides and polyimides containing p‐terphenyl or p‐quinquephenyl moieties in backbone as well as naphthyl pendent groups were synthesized from two new aromatic diamines. The polymers were characterized by inherent viscosity, elemental analysis, FT‐IR, ¹H‐NMR, ¹³C‐NMR, X‐ray, differential scanning calorimetry (DSC), thermomechanical analysis (TMA), thermal gravimetric analysis (TGA), isothermal gravimetric analysis, and moisture absorption. All polymers were amorphous and displayed T_g values at 304–337°C. Polyamides dissolved upon heating in polar aprotic solvents containing LiCl as well as CCl₃COOH, whereas polyimides were partially soluble in these solvents. No weight loss was observed up to 377–422°C in N₂ and 355–397°C in air. The anaerobic char yields were 57–69% at 800°C. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 15–24, 1999     

Synthesis and structures of photoactive rhenium carbonyl complexes derived from 2‐(pyridin‐2‐yl)‐1,3‐benzothiazole, 2‐(quinolin‐2‐yl)‐1,3‐benzothiazole and 1,10‐phenanthroline

Carbon monoxide (CO) has recently been identified as a gaseous signaling molecule that exerts various salutary effects in mammalian pathophysiology. Photoactive metal carbonyl complexes (photoCORMs) are ideal exogenous candidates for more controllable and site‐specific CO delivery compared to gaseous CO. Along this line, our group has been engaged for the past few years in developing group‐7‐based photoCORMs towards the efficient eradication of various malignant cells. Moreover, several such complexes can be tracked within cancerous cells by virtue of their luminescence. The inherent luminecscent nature of some photoCORMs and the change in emission wavelength upon CO release also provide a covenient means to track the entry of the prodrug and, in some cases, both the entry and CO release from the prodrug. In continuation of the research circumscribing the development of trackable photoCORMs and also to graft such molecules covalently to conventional delivery vehicles, we report herein the synthesis and structures of three rhenium carbonyl complexes, namely, fac‐tricarbonyl[2‐(pyridin‐2‐yl)‐1,3‐benzothiazole‐κ²N ,N ′](4‐vinylpyridine‐κN )rhenium(I) trifluoromethanesulfonate, [Re(C₇H₇N)(C₁₂H₈N₂S)(CO)₃](CF₃SO₃), ( 1 ), fac‐tricarbonyl[2‐(quinolin‐2‐yl)‐1,3‐benzothiazole‐κ²N ,N ′](4‐vinylpyridine‐κN )rhenium(I) trifluoromethanesulfonate, [Re(C₇H₇N)(C₁₆H₁₀N₂S)(CO)₃](CF₃SO₃), ( 2 ), and fac‐tricarbonyl[1,10‐phenanthroline‐κ²N ,N ′](4‐vinylpyridine‐κN )rhenium(I) trifluoromethanesulfonate, [Re(C₇H₇N)(C₁₂H₈N₂)(CO)₃](CF₃SO₃), ( 3 ). In all three complexes, the Re^I center resides in a distorted octahedral coordination environment. These complexes exhibit CO release upon exposure to low‐power UV light. The apparent CO release rates of the complexes have been measured to assess their comparative CO‐donating capacity. The three complexes are highly luminescent and this in turn provides a convenient way to track the entry of the prodrug molecules within biological targets.     

trans‐(Cl)‐[Ru(5,5′‐diamide‐2,2′‐bipyridine)(CO)2Cl2]: Synthesis,Structure, and Photocatalytic CO2 Reduction Activity

A series of trans‐(Cl)‐[Ru(L)(CO)₂Cl₂]‐type complexes, in which the ligands L are 2,2′‐bipyridyl derivatives with amide groups at the 5,5′‐positions, are synthesized. The C‐connected amide group bound to the bipyridyl ligand through the carbonyl carbon atom is twisted with respect to the bipyridyl plane, whereas the N‐connected amide group is in the plane. DFT calculations reveal that the twisted structure of the C‐connected amide group raises the level of the LUMO, which results in a negative shift of the first reduction potential (E_p) of the ruthenium complex. The catalytic abilities for CO₂ reduction are evaluated in photoreactions (λ>400 nm) with the ruthenium complexes (the catalyst), [Ru(bpy)₃]²⁺ (bpy=2,2′‐bipyridine; the photosensitizer), and 1‐benzyl‐1,4‐dihydronicotinamide (the electron donor) in CO₂‐saturated N,N‐dimethylacetamide/water. The logarithm of the turnover frequency increases by shifting E_p a negative value until it reaches the reduction potential of the photosensitizer.     

Synthesis and Structures of the Ligands 1‐Methylimidazol‐2‐yl(pyridin‐2‐yl)methanone {(py)(mim)CO} and 1‐Benzylimidazol‐2‐yl(1‐phenylaldimine) (PhN=CHbim) as their Tetracarbonylmolybdenum(0) Complexes [Mo(CO)4(L2‐N,N′)]

The complexes [Mo(CO)₄(L₂‐N,N′)] [L₂ = 1‐methylimidazol‐2‐yl(pyridin‐2‐yl)methanone and 1‐benzylimidazol‐2‐yl(1‐phenylaldimine)] have been synthesized from hexacarbonylmolybdenum(0) in order to define the coordination characteristics of the bidentate nitrogen‐donor ligands; the complexes exhibit distorted octahedral coordination for molybdenum(0) and cis‐bidentate ligand configurations.     

A novel 18‐membered metallocycle in {2,5‐bis[3‐(1H‐1,3‐imidazol‐1‐ylmethyl)phenyl]‐1,3,4‐oxadiazole}dichloridocobalt(II)

The title molecular complex, [CoCl₂(C₂₂H₁₈N₆O)], features a novel 18‐membered Co‐containing metallocycle. The Co^II atom lies in a fairly regular tetrahedral geometry defined by two imidazole N‐atom donors from one 2,5‐bis[3‐(1H‐1,3‐imidazol‐1‐ylmethyl)phenyl]‐1,3,4‐oxadiazole (L) ligand and two chloride anions. The coordinating orientation of the L ligand plays an important role in constructing the metallocycle complex. The complexes form a three‐dimensional supramolecular assembly via nonclassical C—H...Cl and C—H...N hydrogen bonds and π–π interactions.     

Effects of Phenyl‐ and Methyl‐Substituents on p‐Phenylenediamine,an Electrochemical and Spectral Study

Two series of substituted p‐phenylenediamines have been studied for their electronic effects on redox potential and spectral properties. p‐Phenylenediamines and N,N,N′,N”‐tetramethyl‐p‐phenylenediamine substituted with different numbers of phenyl groups have been synthesized and their cyclic voltammograms have been obtained. The correlation between the substituent number and the redox potential appears linear. The slope reflects the additive effect of electron‐donating methyl and electron‐withdrawing phenyl groups. The absorption spectra of the cation radicals indicate that phenyl‐substituted ones have broad intervalence‐charge transfer bands. The p‐phenylenediamines exhibit different properties from triphenylamines in that the oxidized forms are more stable in CH₃CN then those in CH₂Cl₂. Some of the cation radicals or dications could undergo follow‐up chemical reactions and form products that are more easily oxidized.     

Metallorganische 5d6‐Übergangsmetallkomplexe von zwei 1‐Methyl‐(2‐alkylthiomethyl)‐1H‐benzimidazol‐Liganden: Strukturen und elektrochemische Oxidation

Organometallic 5d⁶ Transition Metal Complexes of 1‐Methyl‐(2‐alkylthiomethyl)‐1H‐benzimidazole Ligands: Structures and Electrochemical Oxidation The complexes [(mmb)Re(CO)₃Cl], [(mtb)Re(CO)₃Cl], [(mmb)OsCl(Cym)](PF₆) and [(Cym)OsCl(mtb)](PF₆) where Cym = p‐cymene, mmb = 1‐methyl‐(2‐methylthiomethyl)‐1H‐benzimidazole and mtb = 1‐methyl‐(2‐tert‐butylthiomethyl)‐1H‐benzimidazole were synthesized and, except for the latter, structurally characterized. In comparison with other late transition metal compounds of these N‐S chelate ligands the rhenium(I) systems exhibit a balanced coordination to both N and S donor atoms. Anodic one‐electron oxidation produces EPR‐silent rhenium(II) states whereas the osmium(III) species [(mmb)OsCl(Cym)]²⁺ could be identified via EPR and UV/VIS spectroelectrochemistry.