Ruthenium Phthalocyanine and Its Reaction with Dioxygen: Synthesis, Structure, Magnetism, and Electrical Conductivity Properties of the Cofacially Assembled Ruthenoxane Aggregate of Formula HO−[(Pc)RuO]n−H (Average n = 11)

A Theoretical Probe for Structures, Metal–Metal Bonding, and Electronic Spectra of Paramagnetic Tetrapyrrolic RuII Complex

Dimeric complexes (RuIIPz)2 have been investigated using density functional theory (DFT), where Pz is a porphyrazine ligand that features a 16-atom, 18-π-electron cyclic polyene aromatic skeleton. Structural optimizations in various configurations and spin states indicate that (RuPz)2 favours a Pz–Pz staggered conformer over an eclipsed one; the paramagnetic triplet state with the staggered configuration is found as the global ground state. This agrees with experimental magnetic results of (RuOEPor)2 (OEPor = octaethylporphyrin) and (RuPc)2 (Pc = phthalocyanine). The Ru–Ru bond length was optimized to be 2.38 Å, close to the experimental bond length of 2.40–2.41 Å. The Ru2 doubly bonded nature has been evidenced by the Ru–Ru stretching vibrational frequency of 202 cm–1, bond energy of 30.7 kcal mol–1, and electronic arrangement of σ2π4(nonbonding-δ)4(π*)2. Further confirmation was obtained from high-level wave function theory calculations (complete active space self-consistent field and n-electron valence state second-order perturbation theory). Associated with the solvation of the explicit pyridine accounting for the first coordination sphere and the implicit continuum model for the long-range interaction, the electronic spectra of tetrapyrrolic ruthenium complex were calculated at the time-dependent DFT level.

Nickel(II) 3,4;9,10-perylenediimide bis-phosphonate pentahydrate: a metal-organic ferromagnetic dye

The new metal-organic compound nickel(II) 3,4;9,10-perylenediimide bis-phosphonate pentahydrate, i.e. Ni(2)[(PDI-BP)(H(2)O)(2)]·3H(2)O (1), has been synthesized and its structural and magnetic properties have been studied. Reaction of 3,4;9,10-perylenediimide bis-phosphonate (PDI-BP, hereafter) ligand and nickel chloride in water resulted in the precipitation of a red and poorly crystalline solid (1). As the solid shows a poor crystalline organization of aggregates, the energy dispersive X-ray diffraction analysis (EDXD) technique has been used to obtain short-range order structural information of the single nanoaggregates by radial distribution function analysis. The overall structure of the compound is characterized by layers containing perylene planes shifted in the direction perpendicular to the stacking axes in such a way that only the outer rings overlap. The edges of the perylene planes are connected to the phosphonate groups through an imido group. The oxygen atoms of the [-PO(3)](2-) group and those of the water molecules are bonded to the nickel ions resulting in a [NiO(6)] octahedral coordination sphere. The Ni-O bond lengths are 0.21 ± 0.08 nm and the Ni-O-Ni angles of aligned moieties are 95 ± 2°. The oxygen atoms of the water molecules and the nickel atoms are nearly planar and almost perpendicular to the perylene planes forming chains of edge-sharing octahedra. The magnetic properties of (1) show the presence of intrachain ferromagnetic Ni-Ni interactions and a long-range ferromagnetic order below 21 K with a canting angle and with a spin glasslike behavior due to disorder in the inorganic layer. Hysteresis cycles show a coercive field of ca. 272 mT at 2 K that decreases as the temperature is increased and vanishes at ca. 20 K.

Diphthalocyanine metal complexes and their analogues

The present overview deals with ditetrapyrrolic macrocycles, mainly diphthalocyanine systems, of the following three classes: (a) sandwich-type molecules (I); (b) metal-metal bonded systems (II); (c) single-atom bridged dimers (III). The available information focuses on the structural and electronic features, redox properties and partial oxidation. Practical applications, e.g. electrochromic devices, molecular metals, liquid crystals, non-linear optics, etc., make these classes of complexes particularly attractive and promising materials. The bonding mechanism and the structural, magnetic, conductive and optical properties of these systems are elucidated by density functional calculations.

Electroreduction of nitrite catalyzed by a dinuclear ruthenium phthalocyanine modified graphite electrode

The electrocatalytic reduction of nitrite on a dinuclear ruthenium phthalocyanine ( RuPc )2modified electrode is studied, using cyclic voltammetry (cyclic voltammogram), rotating disc electrode (RDE) and ring-disc electrode (RRDE) techniques. The products of nitrite reduction are ammonia, nitrous oxide, and hydroxylamine. Depending on the experimental conditions, ammonia or nitrous oxide is formed as the main product. The initial step in the electroreduction of nitrite catalyzed by ( RuPc )2is a one electron RuII/ RuIprocess, followed by coordination of NO2−to the metal center. Formation of a nitrosyl complex prior to the electroreduction does not occur. A suitable mechanism is proposed by analyzing the rate equation and the Tafel slope.

Synthesis and spectral properties of ruthenium(II) complexes with tetra-15-crown-5-phthalocyanine and N-donor ligands

The synthesis of novel bis-axially coordinated ruthenium(II) complexes with tetra-15-crown-5-phthalocyanine and N-donor ligands ( R 4 Pc ) Ru ( L 2) ( R 4Pc2- = 4,5,4',5',4'',5'', 4''',5'''- tetrakis(1,4,7,10,13-pentaoxotridecamethylene)phthalocyaninate-ion, L = pyridine (py), isoquino-line (iqnl), triethylamine ( Et 3 N )) is reported. The preparation technique involves the interaction of ( R 4 Pc ) Ru ( CO )( CH 3 OH ) with trimethylamine oxide in an N-donor solvent. The advantage of this method consists in selective carbonyl ejection from ( R 4 Pc ) Ru ( CO ) X with simultaneous substi-tution by N-donor ligands. The application of this procedure allowed us to decrease essentially the reaction time, as compared with photochemical methods, as well as to increase substantially the yield of reaction products. UV-visible, 1 H NMR, FT-IR and mass-spectrometry were used for characterization of the obtained compounds.

Synthesis and characterization of highly soluble hexadecachloro- and hexadecafluorophthalocyanine ruthenium(II) complexes

A new synthesis is reported for hexadecafluorophthalocyanineruthenium(II), F16Pc (2-) RuIIand hexadecachlorophthalocyanineruthenium(II), Cl16Pc (2-) RuII, is reported for the first time. These paramagnetic species, which contain no axial ligand, are quite reasonably soluble in a range of common organic solvents. We report and discuss electronic and vibrational (infrared and resonance Raman) spectroscopic, MALDI-TOF and magnetic data. In addition we report electrochemical data and use spectroelectrochemical methods to obtain the electronic spectra of these species in the phthalocyanine(1-), (3-) and (4-) oxidation states.

Titanium and Ruthenium Phthalocyanines for NO(2) Sensors: A Mini-Review

This review presents studies devoted to the description and comprehension of phenomena connected with the sensing behaviour towards NO₂ of films of two phthalocyanines, titanium bis-phthalocyanine and ruthenium phthalocyanine. Spectroscopic, conductometric, and morphological features recorded during exposure to the gas are explained and the mechanisms of gas-molecule interaction are also elucidated. The review also shows how X-ray reflectivity can be a useful tool for monitoring morphological parameters such as thickness and roughness that are demonstrated to be sensitive variables for monitoring the exposure of thin films of sensor materials to NO₂ gas.

Tetrakis(thiadiazole)porphyrazines. 4. Direct Template Synthesis, Structure, General Physicochemical Behavior, and Redox Properties of AlIII, GaIII, and InIII Complexes

Monometallic derivatives of tetrakis(1,2,5-thiadiazole)porphyrazine, [TTDPzH2], with main group tervalent metal ions having the formulae [TTDPzMX] (TTDPz = tetrakis(1,2,5-thiadiazole)porphyrazinato dianion; M = Al(III), X = Cl-, Br-, OH-; M = Ga(III), X = Cl-, OH-; M = In(III), X = AcO-) were prepared and investigated by single-crystal X-ray analysis and IR and UV-vis spectroscopy as well as cyclic voltammetry and spectroelectrochemistry. The complexes [TTDPzMX] (M = Al(III), X = Cl-, Br-; M = Ga(III), X = Cl-) were obtained by direct autocyclotetramerization of the precursor 3,4-dicyano-1,2,5-thiadiazole in hot quinoline in the presence of MX3 salts (M = Al(III), Ga(III); X = Cl-, Br-) and were hydrolized to form the corresponding hydroxide derivatives, [TTDPzMOH]. The In(III) complex, [TTDPzIn(OAc)], was obtained from the free-base macrocycle [TTDPzH2] with In(OH)(OAc)2 in CH3COOH. A single-crystal X-ray study was made at 173 K on the two isostructural species [TTDPzMCl] (M = Al(III), Ga(III)), which have space group P, with a = 12.470(14), b = 12.464(13), and c = 13.947(12) angstroms, alpha = 70.72(3), beta = 79.76(3), and gamma = 90.06(3) degrees, V = 2009.3(3) angstroms3, and Z = 4 for [TTDPzAlCl] and a = 12.429(3), b = 12.430(3), and c = 13.851(3) angstroms, alpha = 70.663(6), beta = 79.788(8), and gamma = 89.991(9) degrees, V = 1983.3(7) angstroms3, and Z = 4 for [TTDPzGaCl]. Square pyramidal coordination exists about the M(III) centers, with Cl- occupying the apical position (Al-Cl = 2.171(5) and Ga-Cl = 2.193(1) angstroms). Al(III) and Ga(III) are located at distances of 0.416(6) and 0.444(2) angstroms from the center of the N4 system. The molecular packing consists of stacked double layers with internal and external average interlayer distances of 3.2 and 3.3 angstroms, respectively. IR spectra show nu(Al-Cl) at 345 cm(-1) for [TTDPzAlCl], nu(Al-Br) at 330 cm(-1) for [TTDPzAlBr], and nu(Ga-Cl) at 382 cm(-1) for [TTDPzGaCl]. The UV-vis spectra in weakly basic (pyridine, DMF, DMSO) and acidic solvents (CF3COOH, H2SO4) show the typical intense pi --> pi transition bands in the Soret (300-400 nm) and Q-band regions (640-660 nm), the bands evidencing some dependence on the nature of the solvent, particularly in acidic solutions. Cyclic voltammetry, differential pulse voltammetry, and thin-layer spectroelectrochemical measurements in pyridine and dimethylformamide of the species [TTDPzMX] indicate reversible first and second one-electron reductions, whereas additional ill-defined reductions are observed at more negative potentials. The examined species are much easier to reduce than their phthalocyanine or porphyrin analogues as a result of the remarkable electron-attracting properties of the TTDPz macrocycle which contains annulated strongly electron-deficient thiadiazole rings.

The reduction of oxygen and hydrogen peroxide on dinuclear ruthenium phthalocyanine electrocatalytic surfaces

The electrochemical properties of both mononuclear L2RuIIPc and dinuclear [(THF)Rupc]2 species are described. The former is dominated by ring oxidation and reduction processes while the latter displays a series of metal localized processes. A Pourbaix diagram describes the various surfaces which can be generated by exposing a graphite electrode modified with [(THF)Rupc]2 to aqueous buffer at different polarization over a wide range of pH. The behavior of these various surfaces towards the electrocatalytic reduction of both oxygen and hydrogen peroxide is described. Most importantly, three different regimes of hydrogen peroxide reduction are observed dependent on the nature of the modified electrode surface. At high pH the four electron reduction of oxygen to water is observed via a 2 + 2 mechanism.Key words: phthalocyanine, ruthenium, ruthenium phthalocyanine, cyclic voltammetry, suface modified electrode, Pourbaix diagram, electrocatalysis, oxygen reduction, hydrogen peroxide reduction.

X-ray Absorption Spectroscopy Studies of Ruthenoxane Phthalocyanine Derivative HO-[(Pc)RuO](n)()-H

Comprehensive EXAFS investigation carried out on ruthenoxane phthalocyanine and on its chemical precursors ruthenium phthalocyanine dimer and ruthenium bis-pyridine phthalocyanine are reported. The distances around the ruthenium atom were obtained by data analysis and confirm the structural models already proposed for the first two compounds and indicate two pyridines axially coordinated to the central metal for the adduct.