Acenaphthene Complexes Research Articles

Synthesis and the Optical and Electrochemical Properties of Indium(III) Bis(arylimino)acenaphthene Complexes.

Aryl bis(imino)acenaphthenes (Ar-BIANs) are well-established rigid and sterically bulky diimine ligands, which are redox-noninnocent and versatile π-acceptors due to their low-lying π* orbitals and are frequently used to bind transition metals. However, the coordination chemistry of Ar-BIAN ligands to main group elements is not as well-developed as that of their transition metal counterparts. In particular, there are no comprehensive studies describing the spectroscopic and electrochemical properties of main group Ar-BIAN complexes. Herein, we report the synthesis and full characterization of a series of new indium(III) Ar-BIAN complexes, bearing 2,6-dialkyl (1b and 2b), 4-nitro (3b), and 4-dimethylamino (4b) groups at the aryl-diimine part of the ligand. Their optical and electrochemical properties have been revealed by UV-vis spectroscopy and cyclic voltammetry, respectively. Additionally, DFT calculations were performed to gain insights into the nature of the properties displayed.

Voltage clustering in redox-active ligand complexes: mitigating electronic communication through choice of metal ion.

The redox-active bis(imino)acenapthene (BIAN) ligand was used to synthesize homoleptic aluminum, chromium, and gallium complexes of the general formula (BIAN)3M. The resulting compounds were characterized using X-ray crystallography, NMR, EPR, magnetic susceptibility and cyclic voltammetry measurements and modeled using both DFT and ab initio wavefunction calculations to compare the orbital contributions of main group elements and transition metals in ligand-based redox events. Complexes of this type have the potential to improve the energy density and electrolyte stability of grid-scale energy storage technologies, such as redox flow batteries, through thermodynamically-clustered redox events.

Catalytic Polymer Membranes under Forcing Conditions: Reduction of Nitrobenzene by CO/H2O Catalyzed by Ruthenium Bis(arylimino)acenaphthene Complexes

AbstractPolymeric membranes embedding a metal complex have been previously employed as reusable catalysts under relatively mild conditions. Herein, the first example of a polymeric catalytic membrane employed under very forcing conditions (160 °C and 5 MPa CO) is reported. The reaction investigated was the reduction of nitrobenzene to aniline by CO/H2O, catalyzed by ruthenium bis(arylimino)acenaphthene (Ar‐BIAN) complexes. To better retain the complex in the membrane, a modified ligand, with long alkyl chains in the para positions of the aryl rings, was prepared. Among several polymers tested as membranes, PEEK‐WC, a modified polyether ether ketone, gave the best results. Attempts to embed the ligand only in the membrane and functionalize it with the metal later, analogously to the in situ generation of the active species practiced for the homogeneous system, failed and it was necessary to synthesize new complexes that could be reduced under the reaction conditions. Best results were obtained using [Ru(Ar‐BIAN)(CO)2Cl2]+Et3N. During the reaction, the complex is transformed into a mixture of [Ru3(CO)12] and a reduced form of the ligand, Ar‐BIANH2. The latter was independently prepared and shown to be able to reduce nitrobenzene even in the absence of any metal. A new kind of support was designed to allow the placing of the membrane in a stirred autoclave. Using only water as solvent, no metal or ligand leaching was detected and several recycles were performed. All employed membranes were thoroughly characterized by different techniques.

LOWEST EXCITED STATES REORDERING IN (ARENE)M(CO)<sub>3</sub>, WHERE M = Cr or W, COMPLEXES

A series of electronic spectral changes was observed when (arene)M(CO)3 complexes (where arene = benzene, chlorobenzene, phenyltrimethylsilane, acenaphthene, mesitylene, and M = Cr or W) were irradiated with 313 nm light in benzene solution at 298 K in the presence of excess pyridine. These photolysis were neatly leading to the formation of (arene)M(CO)2(py) without any interference from further net photoreaction or thermal reaction on the same time scale. The lower photoreactivity was exhibited by acenaphthene complex. The influences of ring substituents in these complexes and of entering ligands on their photoreactions are discussed in detail with respect to reordering of their electronic states. Keywords: photolysis, arene metal tricarbonyl, excited states reordering

Structure of 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene complexes of non-transition metals from the standpoint of shielding of the central metal

Structure of 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene complexes of non-transition metals from the standpoint of shielding of the central metal

Synthesis of Hyperbranched Polymers with Rhenium(I) Bis(Stilbazoylimino)Acephthalene Complexes at the Branching Units

Two hyperbranched polymers that contains chlorotricarbonyl rhenium(I) bis(stilbazoylimino)acenaphthene complexes were synthesized. The AB2 typed monomers are based on 3- or 4-stilbazoylimino groups that coordinated to the rhenium center as the bidentate ligands. Self-polymerization could be initiated by the addition of silver triflate that activated the rhenium center by removing the chloride ligand. The sizes of the polymers were studied by various methods including gel permeation chromatography and light scattering, and atomic force microscopy. Addition of electrolyte to the polymer solutions resulted in decrease in molecular size, but after a critical concentration (ca. 10 mM), the sizes increased due to the formation of aggregates. These polymers were fabricated into multilayer films by the layer-by-layer electrostatic self-assembly with another polyanion. The multilayer films could function as the active layer in photovoltaic cells. The open-circuit voltage, short circuit current, and fill factor of the best device were measured to be 0.62 V, 3.7 μA/cm2, and 0.17, respectively. The power conversion efficiencies of the cells were in the order of 10−4 %. The contribution of metal complex in the photosensitization process was confirmed by the plot of incident photon-to-electron conversion efficiency as the function of incident light wavelength.

Fabrication of photovoltaic cells using rhenium diimine complex containing polyelectrolytes by the layer-by-layer electrostatic self-assembly method

A series of poly(p-phenylenevinylene)s polycations incorporated with rhenium(I) chlorotricarbonyl bis(phenylimino)acenaphthene complex and pendant pyridinium side groups was synthesized. Due to the presence of ionic pendant groups, the polymers could be used to form multilayer thin films with sulfonated polyaniline (SPAN) by the layer-by-layer (LbL) electrostatic assembly process. The rhenium complexes could function as photosensitizers and SPAN could serve as a charge carrying polymer, and the resulting multilayer films form the active layer of photovoltaic cells. Upon irradiation of the photovoltaic devices by simulated AM 1.5 solar light, the power conversion efficiencies were measured to be of the order of 10−4%. Measurement of the incident photon-to-electron conversion efficiency (IPCE) at different wavelengths confirmed that the photosensitization was due to the presence of rhenium complexes in the polymer. The photocurrent generation and decay processes could be simulated by triexponential functions, which consisted of a rapid process followed by a relatively slow process.

Study of ground state EDA complex formation between [70]fullerene and a series of polynuclear aromatic hydrocarbons

[70]fullerene has been shown to form 1:1 EDA complex with anthracene, naphthalene, phenanthrene, pyrene and acenaphthene in CCl 4 medium. Charge transfer (CT) bands have been detected in all the cases. Isosbestic points have been observed in the cases of phenanthrene and acenaphthene complexes. Ionisation potentials of the donors and CT transition energies have been found to correlate in accordance with Mulliken equation and from this correlation the electron affinity of C 70 has been found to be 2.59 eV. Enthalpies and entropies of formation of the complexes have been estimated from the formation constants of the complexes determined spectrophotometrically at three different temperatures.

Dimerization–Carbostannylation of Alkynes Catalyzed by a Palladium–Diimine Complex: Regioselectivity, Stereoselectivity and Mechanism

Abstract Double insertion of alkynes into the C–Sn bond of an alkynyl-, alkenyl-, allyl- or arylstannane proceeded in the presence of a palladium–diimine complex to afford highly conjugated alkenylstannanes with exclusive syn selectivity. Perfect regioselectivities were observed in the dimerization–carbostannylation of ethyl propiolate with a palladium–1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene complex, which allowed regio- and stereoselective synthesis of stannyl-substituted muconic acid derivatives. The π-conjugation of the dimerization–carbostannylation products was further extended through a cross-coupling or homocoupling reaction. A palladacyclopentadiene is proposed as an intermediate species.

X-ray crystal structure of the 1:1 dimethylpicric acid–acenaphthene complex

The dimethylpicric acid–acenaphthene complex is orthorhombic, space group P212121; at 24° a = 7.3685(1), b = 15.4159(1), c = 16.1296(3) A, D x = 1.491(2) g cm−3, V = 1832.19(4) A3, Z = 4. The phenolic OH group in the dimethylpicric acid is intramolecularly hydrogen bonded to one of the ortho nitro groups with an O⋯O distance of 2.500(2) A. This nitro group is twisted out of the plane of the benzene ring by 8.2°; the twist angles of the other nitro groups are 52.6 and 83.5°. The acenaphthene molecule deviates slightly from planarity as a consequence of the torsion angle at CH 2-CH 2 being 1.8 rather then 0°. The molecules pack in stacks of alternating picric acid and acenaphthene molecules. Each stack is surrounded by a close-packed arrangement of six other stacks. The acenaphthene molecules are 2.7° away from being parallel to the benzene ring in the picric acid. The distances from the benzene ring to the acenaphthene carbon atoms range from 3.26 to 3.49 A on one side of the ring and from 3.30 to 3.54 A on the other.

Nucleophilic addition reactions of [(polyarene)Mn(CO) 3] + complexes containing naphthalene type ligands

[(η 6-Polyarene)Mn(CO) 3] + complexes containing naphthalene type ligands undergo regioselective nucleophilic addition reactions with H- and C-donors to give moderate to good yields of η 5-cyclohexadienyl complexes. Products derived from hydride addition to naphthalene, phenanthrene and acenaphthene complexes have been characterized by X-ray diffraction.