Resonance Raman and Infrared Spectra of Carbene Complexes of Iron Porphyrins Dongsheng Lu

Abstract

The resonance Raman and infrared spectra of four carbene complexes, Fe(TTP)CCl₂, Fe(TPP)¹³CCl₂, Fe(TPP)CBr₂ and Fe(TMP)CCl₂ were measured in the solid state. Based on normal coordinate calculations and observed isotopic shifts by CC1₂/¹³CC1₂ substitution, the v(Fe=C), v_a(CCl₂) and v_s(CCl₂) vibrations were assigned at 1274, 878 and 437cm^?1, respectively. The bromo analogue exhibits these bands at 1270,823 and 364 cm^?1, respectively. All TPP complexes exhibit the spin-state sensitive band (v₂) at 1569 cm^?1 and the oxidation-state sensitive band (v₄) at 1370cm^?1, thus suggesting that the Fe atoms in these carbene complexes are low-spin Fe(IV).     

Tetra(3‐methoxypropionato)diruthenium(II,III) Units: Supramolecular Organization in the Complex [Ru2(μ‐O2CCH2CH2OMe)4(H2O)2]BF4

The synthesis and characterization of Ru₂Cl(μ‐O₂CCH₂CH₂OMe)₄ ( 1 ), [Ru₂(μ‐O₂CCH₂CH₂OMe)₄(H₂O)₂]BF₄ ( 2 ), PPh₄[Ru₂Cl₂(μ‐O₂CCH₂CH₂OMe)₄] ( 3 ), (PPh₄)₂[Ru₂Br₂(μ‐O₂CCH₂CH₂OMe)₄]NO₃ ( 4 ), and (PPh₄)₂[Ru₂I₂(μ‐O₂CCH₂CH₂OMe)₄]I_0.5(NO₃)_0.5 ( 5 ), are described. The structure of complexes 2 – 5 was established by single crystal X‐ray diffraction. All complexes show a diruthenium(II, III) unit bridged by four 3‐methoxypropionate ligands. The cationic complex 2 have two axially coordinated water molecules, with a Ru–Ru bond distance of 2.2681(12) Å. This complex shows a supramolecular two‐dimensional organization across hydrogen bonded between the axial water molecules and two methoxy groups of adjacent diruthenium units. The metal‐metal bond lengths, in the anionic complexes 3 , 4 , and 5 , are 2.3039(5), 2.3077(6), and 2.3115(8) Å, respectively. These distances are longer than the observed in compound 2 . In the anionic complexes, the axial positions of the diruthenium units are occupied by two halide ligands. Complexes 3 – 5 have PPh₄⁺ cations as counterion, although 4 and 5 are double salts with PPh₄NO₃ and PPh₄I_0.5(NO₃)_0.5, respectively. All compounds have been also characterized by elemental analysis, magnetic measurements, and spectroscopic techniques.     

A liquid crystal derived from ­ruthenium(II,III) and a long‐chain carboxylate

The title compound, catena‐poly[[tetrakis(μ‐decanoato‐κ²O:O′)diruthenium(II,III)(Ru—Ru)]‐μ‐octanesulfonato‐κ²O:O′], [Ru₂(C₁₀H₁₉O₂)₄(C₈H₁₇O₃S)], is an octane­sulfonate derivative of the mixed‐valence complex diruthenium tetradecanoate. The equatorial carboxyl­ate ligands are bidentate, bridging two Ru atoms to form a dinuclear structure. Each of the two independent dinuclear metal complexes in the asymmetric unit is located at an inversion centre. The octane­sulfonate anion bridges the two dinuclear units through axial coordination. The alkyl chains of the carboxyl­ate and sulfonate ligands are arranged in a parallel manner. The global structure can be seen as infinite chains of polar moieties separated by a double layer of non‐polar alkyl groups, without interdigitation of the alkyl chains.     

Infrared and Raman spectroscopic characterization of the phosphate mineral kosnarite KZr2(PO4)3 in comparison with other pegmatitic phosphates

In this research, we have used vibrational spectroscopy to study the phosphate mineral kosnarite KZr₂(PO₄)₃. Interest in this mineral rests with the ability of zirconium phosphates (ZP) to lock in radioactive elements. ZP have the capacity to concentrate and immobilize the actinide fraction of radioactive phases in homogeneous zirconium phosphate phases. The Raman spectrum of kosnarite is characterized by a very intense band at 1,026?cm^?1 assigned to the symmetric stretching vibration of the PO₄ ^3? ??₁ symmetric stretching vibration. The series of bands at 561, 595 and 638?cm^?1 are assigned to the ??₄ out-of-plane bending modes of the PO₄ ^3? units. The intense band at 437?cm^?1 with other bands of lower wavenumber at 387, 405 and 421?cm^?1 is assigned to the ??₂ in-plane bending modes of the PO₄ ^3? units. The number of bands in the antisymmetric stretching region supports the concept that the symmetry of the phosphate anion in the kosnarite structure is preserved. The width of the infrared spectral profile and its complexity in contrast to the well-resolved Raman spectrum show that the pegmatitic phosphates are better studied with Raman spectroscopy.     

β‐Carotene Revisited by Transient Absorption and Stimulated Raman Spectroscopy

β‐Carotene in n‐hexane was examined by femtosecond transient absorption and stimulated Raman spectroscopy. Electronic change is separated from vibrational relaxation with the help of band integrals. Overlaid on the decay of S₁ excited‐state absorption, a picosecond process is found that is absent when the C₉‐methyl group is replaced by ethyl or isopropyl. It is attributed to reorganization on the S₁ potential energy surface, involving dihedral angles between C₆ and C₉. In Raman studies, electronic states S₂ or S₁ were selected through resonance conditions. We observe a broad vibrational band at 1770 cm^?1 in S₂ already. With 200 fs it decays and transforms into the well‐known S₁ Raman line for an asymmetric C=C stretching mode. Low‐frequency activity (<800 cm^?1) in S₂ and S₁ is also seen. A dependence of solvent lines on solute dynamics implies intermolecular coupling between β‐carotene and nearby n‐hexane molecules.     

Raman and Photoluminescence Spectroscopic Detection of Surface‐Bound Li+O2− Defect Sites in Li‐Doped ZnO Nanocrystals Derived from Molecular Precursors

We present a detailed study of Raman spectroscopy and photoluminescence measurements on Li‐doped ZnO nanocrystals with varying lithium concentrations. The samples were prepared starting from molecular precursors at low temperature. The Raman spectra revealed several sharp lines in the range of 100–200 cm^?1, which are attributed to acoustical phonons. In the high‐energy range two peaks were observed at 735 cm^?1 and 1090 cm^?1. Excitation‐dependent Raman spectroscopy of the 1090 cm^?1 mode revealed resonance enhancement at excitation energies around 2.2 eV. This energy coincides with an emission band in the photoluminescence spectra. The emission is attributed to the deep lithium acceptor and intrinsic point defects such as oxygen vacancies. Based on the combined Raman and PL results, we introduce a model of surface‐bound LiO₂ defect sites, that is, the presence of Li⁺O₂^? superoxide. Accordingly, the observed Raman peaks at 735 cm^?1 and 1090 cm^?1 are assigned to Li? O and O? O vibrations of LiO₂.     

The structure of mimetite,arsenian pyromorphite and hedyphane – A Raman spectroscopic study

The minerals mimetite Pb₅(AsO₄)₃Cl, arsenian pyromorphite Pb₅(PO₄,AsO₄)₃Cl and hedyphane Pb₃Ca₂(AsO₄)₃Cl have been studied by Raman spectroscopy complimented with infrared spectroscopy. Mimetite is characterised by a band at 812–3 cm⁻¹ attributed to the A_g mode. For the arsenian pyromorphite this band is observed at 818 cm⁻¹ and for hedyphane at 819 cm⁻¹. For mimetite and hedyphane bands at 788 and 765 cm⁻¹ are attributed to A_u and E_1u vibrational modes and are both Raman and infrared active. For the arsenian pyromorphite, Raman bands at 917–1014 cm⁻¹ are attributed to phosphate stretching vibrations. Raman spectroscopy clearly identifies bands attributable to isomorphous substitution of arsenate by phosphate. The observation of low intensity bands in the 3200–3550 cm⁻¹ region are assigned to adsorbed water and OH units, thus indicating some replacement of chloride ions with hydroxyl ions.     

Metal–metal bonding in metal–string complexes M3(dpa)4X2 (M = Ni, Co, dpa = di(2-pyridyl)amido, and X = Cl, NCS) from resonance Raman and infrared spectroscopy

Infrared and Raman spectra for metal–string complexes M₃(dpa)₄X₂ (M = Ni, Co, dpa = di(2-pyridyl)amido, and X = Cl, NCS) are studied. We assign the Ni₃ asymmetric stretching vibration to infrared lines at 304 and 311 cm⁻¹ for Ni₃(dpa)₂Cl₂ and Ni₃(dpa)₂(NCS)₂, respectively. A Raman shift at 242 cm⁻¹ is assigned to the Ni₃ symmetric stretching mode. For Co₃ complexes a line for the Co₃ asymmetric stretching mode appears at 313 and 331 cm⁻¹ for Co₃(dpa)₂Cl₂ and Co₃(dpa)₂(NCS)₂, respectively.     

Ruthenium(III)-Phthalocyanine: Darstelllung und Eigenschaften von Di(halogeno)phthalocyaninato(1−)ruthenium(III), [Ru(X)2Pc] (X = Cl,Br, I)

Ruthenium(III) Phthalocyanines: Synthesis and Properties of Di(halo)phthalocyaninato(1?)ruthenium(III) Di(halo)phthalocyaninato(1?)ruthenium(III), [Ru(X)₂Pc^?] (X = Cl, Br, I) is prepared by oxidation of [Ru(X)₂Pc^2?]^? (Cl, Br, OH) with halogene in dichloromethane. The magnetic moment of [Ru(X)₂Pc^?] is 2,48 μ_B (X = Cl) resp. 2,56 μ_B (X = Br) in accordance with a systeme of two independent spins (low spin Ru^III and Pc^?: S = 1/2). The optical spectra of the red violet solution of [Ru(X)₂Pc^?] (Cl, Br) are typical for the Pc^? ligand with the “B” at 13.5 kK, “Q₁” at 19.3 kK and “Q₂ region” at 31.9 kK. Sytematic spectral changes within the iron group are discussed. The presence of the Pc^? ligand is confirmed by the vibrational spectra, too. Characteristic are the metal dependent bands in the m.i.r. spectra at 1 352 and 1 458 cm^?1 and the strong Raman line at 1 600 cm^?1. The antisymmetric Ru? X stretch (v_as(Ru? X)) is observed at 189 cm^?1 (X = I) resp. 234 cm^?1 (X = Br). There are two interdependent bands at 295 and 327 cm^?1 in the region expected for v_as(Ru? Cl) attributed to strong interaction of v_as(Ru? Cl) with an out-of-plane Pc^? tilting mode of the same irreducible representation. Only the symmetric Ru? Br stretch at 183 cm^?1 is selectively enhanced in the resonance-Raman(RR) spectra. The Raman line at 168 cm^?1 of the diiodo complex is assigned to loosely bound iodine. The broad band at 978 cm^?1 in the RR spectra of the dichloro complex is due to an intraconfigurational transition within the electronic ground state of low spin Ru^III split by spin orbit coupling.     

Catalytic Four‐Electron Oxidation of Water by Intramolecular Coupling of the Oxo Ligands of a Bis(ruthenium–bipyridine) Complex

A bis(ruthenium–bipyridine) complex bridged by 1,8‐bis(2,2′:6′,2′′‐terpyrid‐4′‐yl)anthracene (btpyan), [Ru₂(μ‐Cl)(bpy)₂(btpyan)](BF₄)₃ ([ 1 ](BF₄)₃; bpy=2,2′‐bipyridine), was prepared. The cyclic voltammogram of [ 1 ](BF₄)₃ in water at pH 1.0 displayed two reversible [Ru^II,Ru^II]³⁺/[Ru^II,Ru^III]⁴⁺ and [Ru^II,Ru^III]⁴⁺/[Ru^III,Ru^III]⁵⁺ redox couples at E_1/2(1)=+0.61 and E_1/2(2)=+0.80 V (vs. Ag/AgCl), respectively, and an irreversible anodic peak at around E=+1.2 V followed by a strong anodic currents as a result of the oxidation of water. The controlled potential electrolysis of [ 1 ]³⁺ ions at E=+1.60 V in water at pH 2.6 (buffered with H₃PO₄/NaH₂PO₄) catalytically evolved dioxygen. Immediately after the electrolysis of the [ 1 ]³⁺ ion in H₂¹⁶O at E=+1.40 V, the resultant solution displayed two resonance Raman bands at $\tilde \nu $ =442 and 824 cm^‐1. These bands shifted to $\tilde \nu $ =426 and 780 cm^?1, respectively, when the same electrolysis was conducted in H₂¹⁸O. The chemical oxidation of the [ 1 ]³⁺ ion by using a Ce^IV species in H₂¹⁶O and H₂¹⁸O also exhibited the same resonance Raman spectra. The observed isotope frequency shifts (Δ$\tilde \nu $ =16 and 44 cm^?1) fully fit the calculated ones based on the Ru? O and O? O stretching modes, respectively. The first successful identification of the metal? O? O? metal stretching band in the oxidation of water indicates that the oxygen–oxygen bond at the stage prior to the evolution of O₂ is formed through the intramolecular coupling of two Ru–oxo groups derived from the [ 1 ]³⁺ ion.     

Structure of 4‐biphenylthiolate on Au nanoparticle surfaces studied by UV‐Vis absorption spectroscopy,transmission electron microscopy and surface‐enhanced Raman scattering

Structure of 4‐biphenylthiolate on Au nanoparticle surfaces has been studied by UV‐Vis absorption spectroscopy, transmission electron microscopy and surface‐enhanced Raman scattering (SERS). 4‐Biphenylthiolate is found to have a standing geometry on Au from the presence of the benzene ring CH stretching band identified at ～3060 cm^?1. The ν_8a band at 1597 cm^?1 in the ordinary Raman spectrum was found to split clearly into two features at 1599 and 1585 cm^?1. This result suggests that orientation of the phenyl rings in 4‐biphenylthiolate may be quite different and should not lie in the same plane on Au nanoparticle surfaces. On the basis of the electromagnetic enhancement factor, the dihedral angle could be estimated with a reported value of the tilt angle. Copyright © 2004 John Wiley & Sons, Ltd.     

Aurichalcite – An SEM and Raman spectroscopic study

Raman spectroscopy complimented with supplementary infrared spectroscopy has been used to characterise the vibrational spectrum of aurichalcite a zinc/copper hydroxy carbonate (Zn,Cu²⁺)₅(CO₃)₂(OH)₆. XRD patterns of all specimens show high orientation and indicate the presence of some impurities such as rosasite and hydrozincite. However, the diffraction patterns for all samples are well correlated to the standard reference patterns. SEM images show highly crystalline and ordered structures in the form of micron long fibres and plates. EDAX analyses indicate variations in chemical composition of Cu/Zn ratios ranging from 1/1.06 to 1/2.87. The symmetry of the carbonate anion in aurichalcite is C_s and is composition dependent. This symmetry reduction results in multiple bands in both the symmetric stretching and bending regions. The intense band at 1072 cm⁻¹ is assigned to the ν₁(CO₃)²⁻ symmetric stretching mode. Three Raman bands assigned to the ν₃(CO₃)²⁻ antisymmetric stretching modes are observed for aurichalcite at 1506, 1485 and 1337 cm⁻¹. Multiple Raman bands are observed in 800–850 cm⁻¹ and 720–750 cm⁻¹ regions and are attributed to ν₂ and ν₄ bending modes confirming the reduction of the carbonate anion symmetry in the aurichalcite structure. An intense Raman band at 1060 cm⁻¹ is attributed to the δ OH deformation mode.     

Ship-in-a-bottle formation of Ru3(CO)12 in zeolite NaY

A NaY zeolite entrapped Ru₃(CO)₁₂ cluster has been synthesized from RuCl₃ ionexchanged NaY, which are well characterized by IR and Raman spectroscopy and CO chemisorption. When the Ru³⁺/NaY sample is heated from 298 to 393 K for 25 h and kept for 10–20 h at 393 K, the sample color changes from dark to brown-yellow. Thein situ infrared spectrum exhibits bands at 2130, 2064, 2040, 2017, 1990, 1953 and 1925 cm⁻¹. The bands at 2064, 2040, 2017 and 1990 cm⁻¹ are assigned to Ru₃(CO)₁₂/NaY, which are close to crystalline Ru₃(CO)₁₂. Furthermore, Raman results provide the bands at 150 and 185 cm⁻¹, which are attributed to Ru-Ru bonds of crystalline Ru₃(CO)₁₂). CO chemisorption on [Ru₃]/NaY gives a CO/Ru ratio of 3.85, which is similar to the stoichiometry of Ru₃(CO)₁₂ (CO/Ru=4.0).     

Raman spectroscopic study of the antimonate mineral roméite

Raman spectroscopy has been sued to study the antimony containing mineral roméite Ca₂Sb₂O₆(OH,F,O) from three different origins. Roméite is a calcium antimonate mineral of the pyrochlore group. An intense Raman band at ～518 cm^?1 for roméite is assigned to the SbO ν₁ symmetric stretching mode and the band at 466 cm^?1 to the SbO ν₃ antisymmetric stretching mode. The Raman band at 303 cm^?1 is attributed to the OSbO bending mode. Some variation in band positions is observed and is attributed to the variation in composition between the three mineral samples.     

Controlling Metal–Ligand–Metal Oxidation State Combinations by Ancillary Ligand (L) Variation in the Redox Systems [L2Ru(μ‐boptz)RuL2]n,boptz=3,6‐bis(2‐oxidophenyl)‐1,2,4,5‐tetrazine,and L=acetylacetonate, 2,2′‐bipyridine,or 2‐phenylazopyridine

The new compounds [(acac)₂Ru(μ‐boptz)Ru(acac)₂] ( 1 ), [(bpy)₂Ru(μ‐boptz)Ru(bpy)₂](ClO₄)₂ ( 2 ‐(ClO₄)₂), and [(pap)₂Ru(μ‐boptz)Ru(pap)₂](ClO₄)₂ ( 3 ‐(ClO₄)₂) were obtained from 3,6‐bis(2‐hydroxyphenyl)‐1,2,4,5‐tetrazine (H₂boptz), the crystal structure analysis of which is reported. Compound 1 contains two antiferromagnetically coupled (J=?36.7 cm^?1) Ru^III centers. We have investigated the role of both the donor and acceptor functions containing the boptz^2? bridging ligand in combination with the electronically different ancillary ligands (donating acac^?, moderately π‐accepting bpy, and strongly π‐accepting pap; acac=acetylacetonate, bpy=2,2′‐bipyridine pap=2‐phenylazopyridine) by using cyclic voltammetry, spectroelectrochemistry and electron paramagnetic resonance (EPR) spectroscopy for several in situ accessible redox states. We found that metal–ligand–metal oxidation state combinations remain invariant to ancillary ligand change in some instances; however, three isoelectronic paramagnetic cores Ru(μ‐boptz)Ru showed remarkable differences. The excellent tolerance of the bpy co ‐ ligand for both Ru^III and Ru^II is demonstrated by the adoption of the mixed ‐ valent form in [L₂Ru(μ‐boptz)RuL₂]³⁺, L=bpy, whereas the corresponding system with pap stabilizes the Ru^II states to yield a phenoxyl radical ligand and the compound with L=acac^? contains two Ru^III centers connected by a tetrazine radical‐anion bridge.     

Experimental and DFT Evidence for the Fractional Non‐Innocence of a β‐Diketonate Ligand

New compounds [Ru(pap)₂(L)](ClO₄), [Ru(pap)(L)₂], and [Ru(acac)₂(L)] (pap=2‐phenylazopyridine, L^?=9‐oxidophenalenone, acac^?=2,4‐pentanedionate) have been prepared and studied regarding their electron‐transfer behavior, both experimentally and by using DFT calculations. [Ru(pap)₂(L)](ClO₄) and [Ru(acac)₂(L)] were characterized by crystal‐structure analysis. Spectroelectrochemistry (EPR, UV/Vis/NIR), in conjunction with cyclic voltammetry, showed a wide range of about 2 V for the potential of the Ru^III/II couple, which was in agreement with the very different characteristics of the strongly π‐accepting pap ligand and the σ‐donating acac^? ligand. At the rather high potential of +1.35 V versus SCE, the oxidation of L^? into L^. could be deduced from the near‐IR absorption of [Ru^III(pap)(L^.)(L^?)]²⁺. Other intense long‐wavelength transitions, including LMCT (L^?→Ru^III) and LL/CT (pap^.?→L^?) processes, were confirmed by TD‐DFT results. DFT calculations and EPR data for the paramagnetic intermediates allowed us to assess the spin densities, which revealed two cases with considerable contributions from L‐radical‐involving forms, that is, [Ru^III(pap⁰)₂(L^?)]²⁺?[Ru^II(pap⁰)₂(L^.)]²⁺ and [Ru^III(pap⁰)(L^?)₂]⁺?[Ru^II(pap⁰)(L^?)(L^?)]⁺. Calculations of electrogenerated complex [Ru^II(pap^.?)(pap⁰)(L^?)] displayed considerable negative spin density (?0.188) at the bridging metal.     

Chiral η6‐Arene/N‐Tosylethylenediamine–Ruthenium(II) Complexes: Solution Behavior and Catalytic Activity for Asymmetric Hydrogenation

Aromatic ketones are enantioseletively hydrogenated in alcohols containing [RuX{(S,S)‐Tsdpen}(η⁶‐p‐cymene)] (Tsdpen=TsNCH(C₆H₅)CH(C₆H₅)NH₂; X=TfO, Cl) as precatalysts. The corresponding Ru hydride (X=H) acts as a reducing species. The solution structures and complete spectral assignment of these complexes have been determined using 2D NMR (¹H‐¹H DQF‐COSY, ¹H‐¹³C HMQC, ¹H‐¹⁵N HSQC, and ¹H‐¹⁹F HOESY). Depending on the nature of the solvents and conditions, the precatalysts exist as a covalently bound complex, tight ion pair of [Ru⁺(Tsdpen)(cymene)] and X^?, solvent‐separated ion pair, or discrete free ions. Solvent effects on the NH₂ chemical shifts of the Ru complexes and the hydrodynamic radius and volume of the Ru⁺ and TfO^? ions elucidate the process of precatalyst activation for hydrogenation. Most notably, the Ru triflate possessing a high ionizability, substantiated by cyclic voltammetry, exists in alcoholic solvents largely as a solvent‐separated ion pair and/or free ions. Accordingly, its diffusion‐derived data in CD₃OD reflect the independent motion of [Ru⁺(Tsdpen)(cymene)] and TfO^?. In CDCl₃, the complex largely retains the covalent structure showing similar diffusion data for the cation and anion. The Ru triflate and chloride show similar but distinct solution behavior in various solvents. Conductivity measurements and catalytic behavior demonstrate that both complexes ionize in CH₃OH to generate a common [Ru⁺(Tsdpen)(cymene)] and X^?, although the extent is significantly greater for X=TfO^?. The activation of [RuX(Tsdpen)(cymene)] during catalytic hydrogenation in alcoholic solvent occurs by simple ionization to generate [Ru⁺(Tsdpen)(cymene)]. The catalytic activity is thus significantly influenced by the reaction conditions.     

Experimental and Theoretical Studies on DNA‐Binding and Spectral Properties of ‘Light Switch’ Complexes [Ru(L)2(ppn)]2+ (L=2,2′‐Bipyridine and 1,10‐Phenanthroline; ppn=Pteridino[6,7‐f] [1,10]phenanthroline‐11,13‐diamine)

The ligand pteridino[6,7‐f] [1,10]phenanthroline‐11,13‐diamine (ppn) and its Ru^II complexes [Ru(bpy)₂(ppn)]²⁺ ( 1 ; bpy=2,2′‐bipyridine) and [Ru(phen)₂(ppn)]²⁺ ( 2 ; phen=1,10‐phenanthroline) were synthesized and characterized by elemental analysis, electrospray MS, ¹H‐NMR, and cyclic voltammetry. The DNA‐binding behaviors of 1 and 2 were studied by spectroscopic and viscosity measurements. The results indicate that both complexes strongly bind to calf‐thymus DNA in an intercalative mode, with DNA‐binding constants K_b of (1.7±0.4)?10⁶ M ^?1 and (2.6±0.2)?10⁶ M ^?1, respectively. The complexes 1 and 2 exhibit excellent DNA‐‘light switch’ performances, i.e., they do not (or extremely weakly) show luminescence in aqueous solution at room temperature but are strongly luminescent in the presence of DNA. In particular, the experimental results suggest that the ancillary ligands bpy and phen not only have a significant effect on the DNA‐binding affinities of 1 and 2 but also have a certain effect on their spectral properties. [Ru(phen)₂(ppn)]²⁺( 2 ) might be developed into a very prospective DNA‐‘light switch’ complex. To explain the DNA‐binding and spectral properties of 1 and 2 , theoretical calculations were also carried out applying the DFT/TDDFT method.     

Ketimido Metallophthalocyanines: An Approach to Phthalocyanine‐Supported Mononuclear High‐Valent Ruthenium Complexes

A “metal–ketimine+ArI(OR)₂” approach has been developed for preparing metal–ketimido complexes, and ketimido ligands are found to stabilize high‐valent metallophthalocyanine (M? Pc) complexes such as ruthenium(IV) phthalocyanines. Treatment of bis(ketimine) ruthenium(II) phthalocyanines [Ru^II(Pc)(HN?CPh₂)₂] ( 1a ) and [Ru^II(Pc)(HNQu)₂] ( 1b ; HNQu=N‐phenyl‐1,4‐benzoquinonediimine) with PhI(OAc)₂ affords bis(ketimido) ruthenium(IV) phthalocyanines [Ru^IV(Pc)(N?CPh₂)₂] ( 2a ) and [Ru^IV(Pc)(NQu)₂] ( 2b ), respectively. X‐ray crystal structures of 1b and [Ru^II(Pc)(PhN?CHPh)₂] ( 1c ) show Ru? N(ketimine) distances of 2.075(4) and 2.115(3) Å, respectively. Complexes 2a , 2b readily revert to 1a , 1b upon treatment with phenols. ¹H NMR spectroscopy reveals that 2a , 2b are diamagnetic and 2b exists as two isomers, consistent with a proposed eclipsed orientation of the ketimido ligands in these ruthenium(IV) complexes. The reaction of 1a , 1b with PhI(OAc)₂ to afford 2a , 2b suggests the utility of ArI(OR)₂ as an oxidative deprotonation agent for the generation of high‐valent metal complexes featuring M? N bonds with multiple bonding characters. DFT and time‐dependent (TD)‐DFT calculations have been performed on the electronic structures and the UV/Vis absorption spectra of 1b and 2b , which provide support for the diamagnetic nature of 2b and reveal a significant barrier for rotation of the ketimido group about the Ru? N(ketimido) bond.     

Schwingungs- und Elektronenspektren der Dekahalogenodiosmate(IV), [Os2X10]2−, X  Cl,Br

Vibrational and Electronic Spectra of Decahalogenodiosmates(IV), [Os₂X₁₀]^2?, X ? Cl, Br The IR and Raman spectra of the edge-sharing bioctahedral anions [Os₂X₁₀]^2?, X ? Cl, Br, are assigned according to point group D_2h. The bands are found in three characteristic regions; at high wavenumbers stretching vibrations with terminal ligands v(OsCl_t): 365–280, v(OsBr_t): 235–195; in a middle region with bridging ligands v(OsCl_b): 270–240, v(OsBr_b): 175–165 cm^?1; the deformation bands are observed at distinct lower frequencies. The electronic spectra of the dimers show intraconfigurational transitions near 2000, 1000, and 600 nm which by position and intensity correspond to those of the monomeric complexes. They are therefore discussed separately for both metal centers according to C_2v symmetry. Two additional band systems are presumable pair transitions arising from interactions of the central ions within the dimeric complexes. Due to the different bonding strength of terminal or bridging ligands the intensive charge transfer bands are shifted by 3000–4000 cm^?1 bathochromicly or by 2000–3000 cm^?1 hypsochromicly compared with the hexahaloosmates(IV).