Preparation and structural characterization of Os(II) and Ru(II) complexes,MCl2(vdpp)2 [M = Os or Ru,vdpp = 1,1-bis(diphenylphosphino)ethene]

A reaction between Os₂(O₂CCH₃)₄Cl₂ and vdpp [vdpp = 1,1-bis(diphenylphosphino) ethene] was investigated. When the reactants, in the presence of LiCl, were heated in toluene OsCl₂(vdpp)₂,1, was formed. In a similar reaction Ru₂(O₂CCH₃)₄Cl with vdpp afforded RuCl₂(vdpp)₂,2. The molecular structures of1 and2 were elucidated using X-ray crystallography. Single crystals of1 and2 grown from dichloromethanehexane crystallize in the space group P2₁/c with these cell dimensions: a = 11.046(2)Å, b = 18.168(3)Å, c = 12.678(3)Å, β = 110.24(2)° and V = 2387(2)ų for1 and a = 11.055(1)Å, b = 18.199(3)Å, c = 12.693(2)Å, β = 110.16(1)°, V = 2392(1)ų for2. The molecules of1 and2 are isostructural. Metal atoms reside on inversion centers relating the two halves of the molecules. The complexes are six-coordinate with two four-membered chelate rings and trans chlorine atoms. For RuCl₂(vdpp)₂ the PMP angle in the chelate ring is 73.13(2)° and the PCP angle in the chelate ring is 98.6(1)°. These values are 72.74(3)° and 97.9(2)°, respectively, for OsCl₂(vdpp)₂. There is a disordered dichloromethane solvent molecule present in the lattice and there are no unusual intermolecular contacts.     

Magnetic nanosized {M(II)24}-wheel-based (M = Co, Ni) coordination polymers

Two 3D coordination polymers, [Co(24)(OH)(12)(SO(4))(12)(ip)(6)(DMSO)(18)(H(2)O)(6)]·(DMSO)(6)(EtOH)(6)(H(2)O)(36) (1·guests, ip = isophthalate) and [Ni(24)(OH)(12)(SO(4))(12)(ip)(6)(DMSO)(12)(H(2)O)(12)]·(DMSO)(6)(EtOH)(6)(H(2)O)(20) (2·guests), constructed with nanosized tetraicosanuclear Co(II) and Ni(II) wheels are solvothermally synthesized. Both complexes show intra- and interwheel dominant antiferromagnetic interactions.     

Photogenerated avenues in macromolecules containing Re(I), Ru(II), Os(II), and Ir(III) metal complexes of pyridine-based ligands

Pyridine-based ligands, such as 2,2'-bipyridine and 1,10-phenanthroline, have gained much interest in the fields of supramolecular chemistry as well as materials science. The appealing optoelectronic properties of their complexes with heavy d(6) transition metal ions, such as Ru(ii), Os(II), Re(I) and Ir(III), primarily based on the metal-to-ligand charge-transfer (MLCT) nature featuring access to charge-separated states, have provided the starting point for many studies in the field of dye-sensitized solar cells (DSSCs), organic light emitting diodes (OLEDs), artificial photosynthesis and photogenerated electron as well as energy transfer processes. This critical review provides a comprehensive survey over central advances in the field of soluble metal-containing macromolecules in the last few decades. The synthesis and properties of functionalized 2,2'-bipyridyine- and 1,10-phenanthroline-based d(6) metal complexes, in particular, their introduction into different prevailing polymeric structures are highlighted. In the most part of the review metal complexes which have been attached as pendant groups on the polymer side chain are covered. Selected applications of the herein discussed metal-containing macromolecules are addressed, particularly, with respect to photogenerated electron/energy transfer processes. In order to enable a deeper understanding of the properties of the ligands and metal complexes, the fundamentals of selected photophysical processes will be discussed (223 references).     

True square planar [M{N(SePiPr2)2-Se,Se'}2][M = Sn, Se] complexes. An extraordinary geometrical arrangement for well known centers [Sn(II), Se(II)

The syntheses and molecular structures of [M{N(SeP(i)Pr2)2-Se,Se'}2][M = Sn(2), Se(3)] are described, these complexes consist of discrete, monomeric molecules featuring MSe4 cores that comprise true square-planar geometries.     

Homoleptic, sigma-bonded octahedral superelectrophilic metal carbonyl cations of iron(II), ruthenium(II), and osmium(II). Part 2: Syntheses and characterizations of [M(CO)(6)][BF(4)](2) (M = Fe, Ru, Os)

As the first examples of homoleptic, sigma-bonded superelectrophilic metal carbonyl cations with tetrafluoroborate [BF(4)](-) as the counter anions three thermally stable salts of the composition [M(CO)(6)][BF(4)](2) (M = Fe, Ru, Os) have been synthesized and extensively characterized by thermochemical, structural, and spectroscopic methods. A common synthetic route, the oxidative carbonylation of either Fe(CO)(5) (XeF(2) as the oxidizer) or M(3)(CO)(12) (M = Ru, Os) (F(2) as the oxidizer) in the conjugate Bronsted-Lewis superacid HF/BF(3), was employed. The thermal behavior of the three salts, studied by differential scanning calorimetry (DSC) and gas-phase IR spectroscopy of the decomposition products, has been compared to that of the corresponding [SbF(6)](-) salts. The molecular structures of [M(CO)(6)][BF(4)](2) (M = Fe, Os) were obtained by single-crystal X-ray diffraction at 100 K. X-ray powder diffraction data for [M(CO)(6)][BF(4)](2) (M = Ru, Os) were obtained between 100 and 300 K in intervals of 50 K. All three salts are isostructural and crystallized in the tetragonal space group I4/m (No. 87). As for the corresponding [M(CO)(6)][SbF(6)](2) salts (M = Fe, Ru, Os), similar unit cell parameters and vibrational fundamentals were also found for the three [BF(4)](-) compounds. For the structurally characterized salts [M(CO)(6)][BF(4)](2) (M = Fe, Os), very similar bond parameters for both cations and anions were found. Hence, the invariance of structural and spectroscopic properties of [M(CO)(6)](2+) cations (M = Fe, Ru, Os) extended from the fluoroantimonates [Sb(2)F(11)](-) and [SbF(6)](-) as counteranions also to [BF(4)](-).     

Electron transfer reactions of peroxydisulfate and fluoroxysulfate reactions with the cyanide complexes M(CN)n4- (M=Fe(II), Ru(II), Os(II), Mo(IV), and W(IV))

The stoichiometry and the kinetics of oxidation of the cyanide complexes M(CN)n4- (M = Fe(II), Ru(II), Os(II), Mo(IV), and W(IV)) by the peroxydisulfate ion, S2O8(2-), and by the much more strongly oxidizing fluoroxysulfate ion, SO4F-, were studied in aqueous solutions containing Li+. Reactions of S2O8(2-) with M(CN)n4- are known to be strongly catalyzed by Li+ and other alkali metal ions, and this applies also to the corresponding reactions of SO4F-. The primary reactions of S2O8(2-) and SO4F- have both been found to be one-electron processes in which the equally strong O-O and O-F bonds are broken. The primary reaction of S2O8(2-) consists of a single step yielding M(CN)n3-, SO4-, and SO42-, whereas the primary reaction of SO4F- comprises two parallel one-electron steps, one leading to M(CN)n3-, SO4-, and F- and the other yielding M(CN)n-1(2-), CN-, SO4- and F-. The relationship between the rate constants and the standard free energies of reaction for the Li+-catalyzed reactions of SO4F- and S2O8(2-) with M(CN)n(4-), and for the uncatalyzed reactions of S2O8(2-) with bipyridyl and phenanthroline complexes MLn2+ (M = Fe(II), Ru(II), and Os(II)) studied previously, suggests that the intrinsic barrier for all three sets of reactions is similar, i.e., unaffected by the Li+ catalysis, and that the electron transfer and the breakage of the O-O and O-F bonds are concerted processes.     

Density functional calculation of the electronic circular dichroism spectra of the transition metal complexes [M(phen)3]2+ (M = Fe, Ru, Os)

The circular dichroism spectra of the tris-bidentate metal complexes Lambda-[M(phen)3]2+, with M = Fe, Ru, Os and phen = 1,10-tris-phenanthroline, are investigated computationally, employing time-dependent density functional theory. Good agreement with experimental spectra is obtained for Ru and Os. The Lambda-[Os(phen)3]2+ spectrum is analyzed in detail. It is shown how relativistic effects red shift CD bands where the Os 5d-orbital participates to a large extent in the excitations. Further, the participation of the metal in the ligand pi --> pi exciton CD is determined to be of the order of 10%. Though solvent effects can have a noticeable effect on individual transitions and rotatory strengths, they are demonstrated to have only a very small overall effect on the resulting simulated CD spectra. For Lambda-[Fe(phen)3]2+, the results are shown to be rather sensitive to the choice of the applied hybrid and nonhybrid density functionals, and the optimized geometries based thereupon. In particular, the sign pattern of the lower-energy part (up to 33 x 10(3) cm(-1)) of the Lambda-[Fe(phen)3]2+ CD spectrum is difficult to reproduce. Some combinations of functionals and geometries yield good agreement with experiment, but no "best" approach can be devised based on the available results. Possible sources of errors in the spectrum of Lambda-[Fe(phen)3]2+ due to deficiencies in the functionals and the exchange-correlation kernels are investigated.     

Synthesis, structural characterization, and photophysical, electrochemical, intercomponent energy-transfer, and anion-sensing studies of imidazole 4,5-bis(benzimidazole)-bridged Os(II)Os(II) and Ru(II)Os(II) bipyridine complexes

Homo- and heterobimetallic complexes of composition [(bpy)(2)M(II)(H(2)Imbzim)M'(II)(bpy)(2)](ClO(4))(3)·nH(2)O, where M(II) = M'(II) = Os (1), M(II) = Ru and M'(II) = Os (2), H(3)Imbzim = 4,5-bis(benzimidazole-2-yl)imidazole, and bpy = 2,2'-bipyridine, have been synthesized and characterized using standard analytical and spectroscopic techniques. Both of the complexes crystallized in monoclinic form with the space group P2(1)/m for 1 and P2(1)/n for 2. The absorption spectra, redox behavior, and luminescence properties of the complexes have been thoroughly investigated. The complexes display very intense, ligand-centered absorption bands in the UV region and moderately intense metal-to-ligand charge-transfer (MLCT) bands in the visible region. The bimetallic complexes show two successive one-electron reversible metal-centered oxidations. The strong fluorescence of free H(3)Imbzim is completely quenched in the metal complexes by energy transfer to the metal-based units, which exhibit their characteristic MLCT phosphorescence. The luminescence data of the heterometallic complex 2 show that electronic energy transfer takes place from the ruthenium center to the osmium-based component. The anion binding properties of the complexes have been studied in solutions using absorption, emission, and (1)H NMR spectral measurements. The metalloreceptors act as sensors for F(-) and AcO(-) ions. Sensing studies indicate the presence of two successive anion-induced deprotonation steps, leading to the formation of [(bpy)(2)M(HImbzim)M'(bpy)(2)](2+) and [(bpy)(2)M(Imbzim)M'(bpy)(2)](+) species. Double deprotonation is also observed in the presence of hydroxide. The binding affinities of different anions toward the receptors have been evaluated. Cyclic voltammetry measurements carried out in acetonitrile have provided evidence in favor of anion-dependent electrochemical responses of the bimetallic metalloreceptors with F(-) and AcO(-) ions.     

Contemporary progresses on neutral, highly emissive Os(II) and Ru(II) complexes

This tutorial review highlights recent and current advances in Os(II) and Ru(II) based luminescent complexes in view of their potential in providing models for photophysical properties and in serving as active materials in optoelectronic devices. It starts with a discussion of the fundamentals of pyridyl azolate chromophores and presents several prototypical designs that allow subtle variation of their basic properties. The third section of this article concerns the preparation of Os(II) and Ru(II) metal complexes and discusses the key factors that control their phosphorescence efficiencies and peak wavelengths. Attention is focused on the properties of their lowest lying excited states. In the last section, we present a series of related Os(II) complexes possessing pyridyl azolate, cyclometalated benzo[h]quinoline, beta-diketonates and quinolinates to demonstrate the power of fundamental basis to chemistry and theoretical approaches in rationalizing the corresponding photophysical behavior and hence to discuss the implications regarding their possible routes for future research.     

Electrochemical, spectroscopic, and photophysical properties of structurally diverse polyazine-bridged Ru(II),Pt(II) and Os(II),Ru(II),Pt(II) supramolecular motifs

Five new tetrametallic supramolecules of the motif [{(TL)(2)M(dpp)}(2)Ru(BL)PtCl(2)](6+) and three new trimetallic light absorbers [{(TL)(2)M(dpp)}(2)Ru(BL)](6+) (TL = bpy = 2,2'-bipyridine or phen = 1,10-phenanthroline; M = Ru(II) or Os(II); BL = dpp = 2,3-bis(2-pyridyl)pyrazine, dpq = 2,3-bis(2-pyridyl)quinoxaline, or bpm = 2,2'-bipyrimidine) were synthesized and their redox, spectroscopic, and photophysical properties investigated. The tetrametallic complexes couple a Pt(II)-based reactive metal center to Ru and/or Os light absorbers through two different polyazine BL to provide structural diversity and interesting resultant properties. The redox potential of the M(II/III) couple is modulated by M variation, with the terminal Ru(II/III) occurring at 1.58-1.61 V and terminal Os(II/III) couples at 1.07-1.18 V versus Ag/AgCl. [{(TL)(2)M(dpp)}(2)Ru(BL)](PF(6))(6) display terminal M(dπ)-based highest occupied molecular orbitals (HOMOs) with the dpp(π*)-based lowest unoccupied molecular orbital (LUMO) energy relatively unaffected by the nature of BL. The coupling of Pt to the BL results in orbital inversion with localization of the LUMO on the remote BL in the tetrametallic complexes, providing a lowest energy charge separated (CS) state with an oxidized terminal Ru or Os and spatially separated reduced BL. The complexes [{(TL)(2)M(dpp)}(2)Ru(BL)](6+) and [{(TL)(2)M(dpp)}(2)Ru(BL)PtCl(2)](6+) efficiently absorb light throughout the UV and visible regions with intense metal-to-ligand charge transfer (MLCT) transitions in the visible at about 540 nm (M = Ru) and 560 nm (M = Os) (ε ≈ 33,000-42,000 M(-1) cm(-1)) and direct excitation to the spin-forbidden (3)MLCT excited state in the Os complexes about 720 nm. All the trimetallic and tetrametallic Ru-based supramolecular systems emit from the terminal Ru(dπ)→dpp(π*) (3)MLCT state, λ(max)(em) ≈ 750 nm. The tetrametallic systems display complex excited state dynamics with quenching of the (3)MLCT emission at room temperature to populate the lowest-lying (3)CS state population of the emissive (3)MLCT state.     

Preparation and structures of dinuclear complexes containing M(II)-OH centers

The synthesis of M(II)(2) complexes (M(II)=Co, Mn) with terminal hydroxo ligands has been achieved utilizing a dinucleating ligand containing a bridging pyrazolate unit and appended (neopentyl)aminopyridyl groups. Structural studies on the complexes revealed that the M(II)-OH units are positioned in a syn-configuration, placing the hydroxo ligands in close proximity (ca. 3 ? apart), which may be a prerequisite for water oxidation.     

(M4H3X)2B2O2: hydrometal complexes (M = Ni, Mg) containing double tetracoordinate planar nonmetal centers (X = C, N)

Geometrical optimizations and electronic structural analyses of the -O(2)B(2)- bridged hydrometal complexes (M(4)H(3)C)(2)B(2)O(2) and (M(4)H(3)N)(2)B(2)O(2)(2+) (M = Ni, Mg) containing double tetracoordinate planar nonmetals (TPN) have been performed using the density functional theory at the B3LYP/6-311+G(d,p) level. Theoretical evidence of the possibility of double TPN centers coexisting in one planar molecule is presented.     

Structural Characterization of Some Coinage Metal(I) Thiosulfate Complexes, $\rm M^{1}_{a}M\rm ^{2}_{b}(X_{c}) (S_{2}O_{3})_{d}(\cdot eS)$ (M1 = Group 1 Cation,X = Univalent Anion,M2 = CuI,AgI, S = Solvent)

Building on previous single crystal X‐ray structure determinations for the group 1 salts of complex thiosulfate/univalent coinage metal anions previously defined for (NH₄)₉AgCl₂(S₂O₃)₄, NaAgS₂O₃·H₂O and Na₄[Cu(NH₃)₄][Cu(S₂O₃)₂]·NH₃, a wide variety of similar salts, of the form , M¹ = group 1 metal cation, M² = univalent coinage metal cation (Cu, Ag), (X = univalent anion), most previously known, but some not, have been isolated and subjected to similar determinations. These have defined further members of the isotypic, tetragonal series, for M¹ = NH₄, M² = Cu, Ag, X = NO₃, Cl, Br, I, together with the K/Cu/NO₃ complex, all containing the complex anion [M²(SSO₃)₄]^7? with M² in an environment of symmetry, Cu, Ag‐S typically ca. 2.37, 2.58Å, with quasi‐tetrahedral S‐M‐S angular environments. Further salts of the form , n = 1‐3, have also been defined: For n = 3, M² = Cu, M¹/x = K/2.25 or 1 5/6, NH₄/6, (and also for the (NH₄)₄Na/4H₂O·MeOH adduct) the arrays take the form with distorted trigonal planar CuS₃ coordination environments, Cu‐S distances being typically 2.21Å, S‐Cu‐S ranging between 105.31(4)–129.77(4)°; the silver counterparts take the form for M¹ = K, NH₄. For n = 2, adducts have only been defined for M² = Ag, the anions of the M¹ = Na, K adducts being dimeric and polymeric respectively: Na₆[(O₃SS)₂Ag(μ‐SSO₃)₂Ag(SSO₃)]·3H₂O, K₃[Ag(μ‐SSO₃)₂]_(∞|∞)·H₂O; a polymeric copper(I) counterpart of the latter is found in Na₅Cu(NO₃)₂(S₂O₃)₂ ≡ 2NaNO₃·Na₃[Cu(μ‐SSO₃)₂]_(∞|∞). For n = 1, NaAgS₂O₃, the an‐ and mono‐ hydrates, exhibit a two‐dimensional polymeric complex anion in both forms but with different contributing motifs. (NH₄)₁₃Ag₃(S₂O₃)₈·2H₂O takes the form (NH₄)₁₃[{(O₃SS)₃Ag(μ‐SSO₃)}₂Ag], a linearly coordinated central silver atom linking a pair of peripheral [Ag(SSO₃)₄]^7? entities. In Na₆[(O₃SS)Ag(μ‐SSO₃)₂Ag(SSO₃)]·3H₂O, the binuclear anions present as Ag₂S₄ sheets, the associated oxygen atoms being disposed to one side, thus sandwiching layers of sodium ions; the remarkable complex Na₅[Ag₃(S₂O₃)₄]_(∞|∞)·H₂O is a variant, in which one sodium atom is transformed into silver, linking the binuclear species into a one‐dimensional polymer. In (NH₄)₈[Cu₂(S₂O₃)₅]·2H₂O a binuclear anion of the form [(O₃SS)₂Cu(μ‐S.SO₃)Cu(SSO₃)₂]^8? is found; the complex (NH₄)₁₁Cu(S₂O₃)₆ is 2(NH₄)₂(S₂O₃)·(NH₄)₇[Cu(SSO₃)₄]. A novel new hydrate of sodium thiosulfate is described, 4Na₄S₂O₃·5H₂O, largely describable as sheets of the salt, shrouded in water molecules to either side, together with a redetermination of the structure of 3K₂S₂O₃·H₂O.     

Mono{hydrotris(mercaptoimidazolyl)borato} complexes of manganese(II), iron(II), cobalt(II), and nickel(II) halides

A series of [Tm(Me)M(mu-Cl)]2 and Tm(R)MCl (Tm(R) = tris(mercaptoimidazolyl)borate; R = Me, tBu, Ph, 2,6-iPr2C6H3 (Ar); M = Mn, Fe, Co, Ni) complexes have been prepared by treatment of NaTm(Me) or LiTm(R) with an excess amount of metal(II) chlorides, MCl2. Treatment of Tm(R)MCl (R = tBu, Ph, Ar) with NaI led to a halide exchange to afford Tm(R)MI. The molecular structures of [Tm(Me)M(mu-Cl)]2 (M = Mn, Ni), [Tm(Me)Ni(mu-Br)]2, Tm(tBu)MCl (M = Fe, Co), Tm(Ph)MCl (M = Mn, Fe, Co, Ni), Tm(Ar)MCl (M = Mn, Fe, Co, Ni), Tm(Ph)MI (M = Mn, Co), and Tm(Ar)MI (M = Fe, Co, Ni) have been determined by X-ray crystallography. The Tm(R) ligands occupy the tripodal coordination site of the metal ions, giving a square pyramidal or trigonal bipyramidal coordination geometry for Tm(Me)M(mu-Cl)]2 and a tetrahedral geometry for the Tm(R)MCl complexes, where the S-M-S bite angles are larger than the reported N-M-N angles of the corresponding hydrotris(pyrazolyl)borate (Tp(R)) complexes. Treatment of Tm(Ph)2Fe with excess FeCl2 affords Tm(Ph)FeCl, indicating that Tm(R)2M as well as Tm(R)MCl is formed at the initial stage of the reaction between MCl2 and the Tm(R) anion.     

Synthesis and structures of 1,1′-bis(diphenylphosphino)metallocenyl complexes M(η 5-C5H4PPh2)2Ru(H2O)2(OTs)2 (M = Fe, Ru, or Os)

The reaction of equimolar amounts of M(η⁵-C₅H₄PPh₂)₂ (M = Fe, Ru, or Os) and [Ru(H₂O)₆](OTs)₂ afforded the M(η⁵-C₅H₄PPh₂)₂Ru(H₂O)₂(OTs)₂ complexes, which were characterized by elemental analysis and ¹H, ¹³C, and ³¹P NMR spectroscopy. The structure of the osmocene complex was established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 659—661, April, 2006.     

Remarkable metal-rich ternary chalcogenides Sc14M3Te8 (M = Ru,Os)

In this novel motif, scandium atoms define infinite parallel chains of alternate trans-face-sharing cubes and pairs of square antiprisms in which each polyhedron is also centered by an M atom (M = Ru, Os). These chains are further linked into a three-dimensional structure by Sc(Te2Te4/2) octahedra. Physical property measurements show Sc14Ru3Te8 to be metallic and Pauli-paramagnetic, consistent with the results of extended Hückel band structure calculations. Matrix effects are evident in the dimensions within the chains. The major interactions are Sc-M and Sc-Te.     

Construction of triangular metallomacrocycles: [M3(1,2-bis(2,2':6',2''-terpyridin-4-yl-ethynyl)benzene)3][M = Ru(II), Fe(II), 2Ru(II)Fe(II)

Complexation of a predesigned (1,2-bis(2,2':6',2'-terpyridin-4-yl-ethynyl)benzene) ligand possessing a 60 degrees angle between two terpyridines with transition metals [Fe(II) and Ru(II)] afforded the self-assembled, triangular metallomacrocycles.     

Photochromic dithienylethene derivatives containing Ru(II) or Os(II) metal units. Sensitized photocyclization from a triplet state

Efficient photocyclization from a low-lying triplet state is reported for a photochromic dithienylperfluorocyclopentene with Ru(bpy)3 units attached via a phenylene linker to the thiophene rings. The ring-closure reaction in the nanosecond domain is sensitized by the metal complexes. Upon photoexcitation into the lowest Ru-to-bpy 1MLCT state followed by intersystem crossing to emitting 3MLCT states, photoreactive 3IL states are populated by an efficient energy-transfer process. The involvement of these 3IL states explains the quantum yield of the photocyclization, which is independent of the excitation wavelength but decreases strongly in the presence of dioxygen. This behavior differs substantially from the photocyclization of the nonemissive dithienylperfluorocyclopentene free ligand, which occurs from the lowest 1IL state on a picosecond time scale and is insensitive to oxygen quenching. Cyclic voltammetric studies have also been performed to gain further insight into the energetics of the system. The very high photocyclization quantum yields, far above 0.5 in both cases, are ascribed to the strong steric repulsion between the bulky substituents on the dithienylperfluorocyclopentene bridge bearing the chelating bipyridine sites or the Ru(bpy)3 moieties, forcing the system to adopt nearly exclusively the reactive antiparallel conformation. In contrast, replacement of both Ru(II) centers by Os(II) completely prevents the photocyclization reaction upon light excitation into the low-lying Os-to-bpy 1MLCT state. The photoreaction can only be triggered by optical population of the higher lying 1IL excited state of the central photochromic unit, but its yield is low due to efficient energy transfer to the luminescent lowest 3MLCT state.