Theoretical Studies on the Excited-state Properties of Ru(Ⅱ) Polypyridyl Complexes

Using DFT/TDDFT methods,the excited-state lifetimes of Ru(Ⅱ) polypyridyl complexes were computed accurately and the reason of Ru(Ⅱ) polypyridyl complexes with long excited-state lifetimes was explained by the electron-transfer distances and HOMO-LUMO gaps.Finally,the photovoltaic conversion efficiencies of complexes were predicted using DFT and docking methods.This work has provided methods of predicting the excited-state lifetimes and photovoltaic conversion efficiencies of Ru(Ⅱ) polypyridyl complexes.     

Access to Bis(σ-B−H) Complexes of Ruthenium Bearing Monoaryl Borate and Borane Ligands

A series of ruthenium bis(σ-B−H) borate complexes 1 – 4 have been prepared by a salt-elimination protocol using lithium monoaryl trihydroborates Li[ArBH₃] (R=Ph, 3,5-(CF₃)₂C₆H₃, o-tol or Mes) and the corresponding metal halide Cp*Ru(PCy₃)Cl. All of these bis(σ-B−H) borate complexes are stable at room temperature and isolated in good yields (70–92 %). Additionally, treatment of 4 with the hydride abstracting agent B(C₆F₅)₃ generated rare cationic bis(σ-B−H) borane complex 5 . Crystallographic characterization data are provided for 3 and 5 . All these new complexes were fully characterized by multinuclear NMR spectroscopy and elemental analysis.     

Synthesis and Thermal Rearrangement of Tetramethyldisilane-bridged Bis(cyclopentadienyl) Diiron Complexes with Bis(phosphine)Substitution

Photolysis of [Me2SiSiMe2)[C5H4Fe(CO2)]2with a series of bis(phosphine)ligands Ph2P(CH2)n PPh2(n=1-4) leads to the formation of the corresponding diiron complexes with intramolecular and intermolecular bis(phosphine) substitution.When these complexes were heated in refluxing xylene.only in the complexes with intermolecular bis(phosphine )substitution the thermal rearrangement reaction occurred.     

Synthesis and Structure of Binary Complexes of Platinum Group Metals — Precursors of Metallic Materials

This paper reviews the results of structural studies of binary complexes whose cationic part contains cobalt, rhodium, iridium, ruthenium, and chromium chloropentammne. The structure of these compounds is discussed in the light of the design of new multicomponent precursor compounds. Data are given on the chemical and phase compositions of the polymetallic powders resulting from the thermal decomposition of the compounds studied.     

Studies on Transition Metal Complexes of Schiff Base( Ⅰ )——Oxygen-carrying Properties of Cobalt( Ⅱ )Schiff Base Complexes

Introduction The compounds that can take up and release molecular oxygen reversibly is of significance because they can be used as model compounds for the study of the reversible oxygenation mechanisms involved in the very complex natural oxygen carriers, e.g., the hemoglobins and hemocyanins, and as the means of separating molecular oxygen from the air. The dioxygen carriers extensively studied are the Cobalt     

TDDFT Studies of Electronic Structure and First Hyperpolarizability of Tetra-nuclear Cubane-like Transition Metal Clusters

A series of tri-nuclear transition metal clusters with incomplete cubane-like configurations have been studied by TDDFT method. The calculations show that they have enormously large second-order polarizabilities () and are potential nonlinear optical materials for infrared double frequency conversion1. In this paper some tetra-nuclear transition metal clusters with cubane-like configurations, MCu3X4 (PPh3)3 (M=W, Mo; X= S, O, Cl, Se, Br), were studied by TDDFT method for a reference…     

Impact of Group 10 Metals on the Solvent-Induced Disproportionation of o-Semiquinonato Complexes

The oxidation of [M^II(3,5-DTBCat)(DTBbpy)] (M=Ni ( [Ni] ), Pd ( [Pd] ), and Pt ( [Pt] ); 3,5-DTBCat=3,5-di-tert-butylcatecholato; DTBbpy=4,4′-di-tert-butyl-2,2′-bipyridine) afforded the dimeric {[Ni^II(3,5-DTBSQ)(DTBbpy)](PF₆)}₂ ( {[Ni](PF₆)}₂ ; 3,5-DTBSQ=3,5-di-tert-butylsemiquinonato) and monomeric semiquinonato (SQ) complexes [M^II(3,5-DTBSQ)(DTBbpy)](PF₆) (M=Pd ( [Pd](PF₆) ) and Pt ( [Pt](PF₆) )). The negative solvatochromic properties of the SQ complexes allowed us to estimate the relative order of their dipole moments: [Pd](PF₆) > [Pt](PF₆) > {[Ni](PF₆)}₂ . The complexes [Pd](PF₆) and [Pt](PF₆) adopt monomeric structures and are stable in CH₂Cl₂ and toluene, whereas they gradually disproportionate at room temperature to [M] and 3,5-di-tert-butylbenzoquinone (3,5-DTBBQ) in polar solvents such as THF, MeOH, EtOH, DMF, or DMSO. The results of spectroscopic studies suggested that the oxidized nickel complex adopts a monomeric structure ( [Ni](PF₆) ) in CH₂Cl₂, but a dimeric structure ( {[Ni](PF₆)}₂ ) in the other investigated solvents. In polar solvents, {[Ni](PF₆)}₂ may disproportionate to [Ni] and 3,5-DTBBQ at 323 K, thereby demonstrating a significant solvent- and metal-dependence in temperature. The relative activities of {[Ni](PF₆)}₂ and [M](PF₆) toward disproportionation are related to the electrochemically estimated K_dis values in CH₂Cl₂ and DMF. The present work demonstrates that solvent polarity and the dipole moments of the SQ complexes promote disproportionation, which can be controlled by a judicious choice of the metal ion, solvent, and temperature.     

Crystal Structures and Characterizations of Bis(pyrrolidinedithiocarbamato) Cu(II) and Zn(II) Complexes

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Sandwich Complexes of the As_4～(2-) Aromatic Ring with Some Transition Metals

The equilibrium geometries,energies,harmonic vibrational frequencies,and nucleus independent chemical shifts(NICS) of the new type sandwich structures [As4MAs4]n-(M = Fe,Co,Ni,Ru,Rh,Pd,Os,Ir and Pt;n = 0,1 or 2) are investigated at the B3LYP level.All the [As4MAs4]n-species adopt staggered(D4d) conformations as their stable structures and eclipsed(D4h) conformations as their transition states,and once the sandwich complexes are formed,the As42- square properties remain unchanged.The NICS calculation confirms that the complexes of Fe,Co,and Ni are aromatic with negative NICS values,and those of Ru,Rh,and Ir exhibit slight aromaticity,while those of Pd,Os,and Pt show slight antiaromaticity.     

Kinetics and Mechanism of Thermal Decomposition of Bis(η3-Allyl)Nickel Complexes

Kinetics and Catalysis - The kinetics of thermal decomposition of bis(η3-allyl) nickel complexes in various media is studied. The specific features of the mechanism are determined, including...     

Synthesis and Crystal Structures of the α and β Forms of Bis(salicylaldoxime)copper(Ⅱ) Complexes

Modified α and β bis(salicylaldoxime)copper(Ⅱ) have been obtained by recrystallization from ethyl acetate(CCDC Nos. 212157 & 212158). The X-ray analysis reveals that the two modificated forms have the same structure with different geometric parameters. The α form crystallizes in the P2(1)/c space group and the β form in the P1 space group. Both the crystal structures consist of centrosymmetric monomeric molecules of Cu(OC6H4CNOH)2. The IR spectra are in agreement with the structural data.     

Cyclometallaphosphiniminatopxosphane (and Arsane) Complexes of “Early” and “Late” Transition Metals Derived from Novel Heterodifunctional Phosphorus and Arsenic Ligands

Abstract

A new heterodifunctional ligand system Me₃EN=PPh₂(CH₂)_nQPh₂ (E - Si, Ge; Q = P, As; n ? 1, 2) has been developed. These heterodifunctional ligands provide hard (N) and soft (P, As) base character appropriate for combination with “early” and “late” transition metals respectively to form chelate and monodentate complexes. In addition M-N [sgrave] bond formation by means of metathetical Me₃EX elimination leads to a variety of useful functionalized phosphanes. Interactions with Ti(IV), Mo(O), W(O), Pd(II), Rh(I) and Ir(I) indicate the versatility of these ligands     

Synthesis and Electrochemical Studies of Ruthenium(II) Dicarbonyl Bis(ferrocenyl-β-diketonates)

The reaction of [Ru₃(CO)₁₂] ( 1 ) with six equiv. of FcC(O)CH₂C(O)R ( 2a , R = Me; 2b , R = Fc; Fc = Fe(η⁵-C₅H₄)(η⁵-C₅H₅)) produced the Ru^II compounds [Ru(CO)₂(FcC(O)CHC(O)R)₂] ( 3a , R = Me; 3b , R = Fc) in moderate yields. IR studies and single-crystal X-ray analysis ( 3a ) confirmed that the CO ligands are cis-oriented and that the respective β-diketonates O,O'-chelate-bonded setting-up an octahedral surrounding at Ru^II. Electrochemical (cyclic and square-wave voltammetry) and spectroelectrochemical (UV/Vis-NIR, IR) measurements were additionally carried out. Compounds 3a , b display two ( 3a : E₁^o' = 140; E₂^o' = 255 mV; ΔE^o' = 115 mV for [ 3a ]⁺/[ 3a ]²⁺) or four ( 3b : E₁^o' = 80 mV, E₂^o' 190 mV (ΔE^o' = 110 mV, [ 3b ]⁺/[ 3b ]²⁺), E₃^o' = 355 mV (ΔE^o' = 165 mV, [ 3b ]²⁺/[ 3b ]³⁺), E₄^o' = 490 mV (ΔE^o' = 135 mV, [ 3b ]³⁺/[ 3b ]⁴⁺)) electrochemical reversible one-electron redox processes indicating electrostatic interactions among the ferrocenyl groups as oxidation progresses, which was confirmed by UV/Vis-NIR and in situ IR spectroscopy. One ferrocenyl group on each β-diketonate ligand is by this means 1^st oxidized before the 2^nd ferrocenyl group of the same β-diketonate building block follows.     

Studies of Unusual Oxidation States of Transition Metals Ⅱ——Kinetics and Mechanism of Oxidation of Pyruvate by Diperiodatoargentate (Ⅲ)Ion

The kinetics of oxidation of pyruvate by diperiodatoargentate( III) ion (DPA) has been studied spec-trophotometrically in alkaline medium. It was found that the reaction order with respect to both DPA and pyruvate is unity and the rate equation can be expressed asThe rate increases with the increase in [OH ] and decreases with the increase in [periodate]. There is a positive ionic strength effect in this reaction system. A mechanism has been proposed to explain the experimental results. The observed activation parameters are presented.     

Electrochemical Behavior of Novel Bis(β-diketonate)phthalocyanine Complexes of Zr(IV) and Hf(IV)

We have used cyclic voltammetry to study the electrochemical properties of novel bis(-diketonate)phthalocyanine complexes of Zr(IV) and Hf(IV) in dichloromethane. We found three waves for the studied complexes that can be attributed to one-electron processes MPc(L)^0/1– ₂, MPc(L)^1+/0 ₂ and MPc(L)^2+/1+ ₂. We have shown that the electrochemical behavior of the complexes depends on the nature of the substituents in axial ligands and does not depend on the nature of the metals. We have analyzed the stability of the one-electron oxidation products of the complexes relative to disproportionation.     

Experimental and Theoretical Studies on the Inclusion Complexation of β-Cyclodextrin with Phenothiazine Derivatives

Inclusion complexation of -cyclodextrin (-CD) with N-phenylphenothiazine ( 1), N-benzylphenothiazine ( 2) and N-phenethylphenothiazine ( 3) has been studied by means of UV-vis spectroscopy and molecular dynamics simulations. The association constants (K_a) were determined to be 126, 312 and 211 dm³/mol for inclusion of -CD with 1, 2 and 3, respectively. It shows that the K_a values are affected by the substituents of the guest compounds. The structures of the complexes and the conformation of the guest compounds bound by -CD in the complex have been discussed.     

Bonding Situation of σ-E−H Complexes in Transition Metal and Main Group Compounds

The ambiguous bonding situation of σ-E−H (E=Si, B) complexes in transition metal compounds has been rationalized by means of Density Functional Theory calculations. To this end, the combination of the Energy Decomposition Analysis (EDA) method and its Natural Orbital for Chemical Valance (NOCV) extension has been applied to representative complexes described in the literature where the possible η¹ versus η² coordination mode is not unambiguously defined. Our quantitative analyses, which complement previous data based on the application of the Quantum Theory of Atoms in Molecules (QTAIM) approach, indicate that there exists a continuum between genuine η¹ and η² modes depending mainly on the strength of the backdonation. Finally, we also applied this EDA-NOCV approach to related main-group species where the backdonation is minimal.     

Synthesis and Structures of Dinuclear Aluminum Complexes Based on Bis(β-diketiminate) Ligands

A series of ten dinuclear aluminum alkyl complexes based on rigid, semirigid, and flexible bis(β-diketiminate) ligands (NacNac) has been obtained from the reaction of trimethylaluminum and the corresponding bis(β-diketimine)s. All compounds were fully characterized using NMR and IR spectroscopy and elemental analysis. The molecular structures of five compounds have been investigated by means of single-crystal X-ray diffraction analysis.     

Solid and Solution Structural Studies of Dimeric and Tetrameric Molybdenum(Ⅵ) Malate Complexes

Reactions of potassium molybdate with racemic malic acid (H3mal = C4H6O5) result in the isolation of two mesomeric molybdenum malate complexes Ks[(MoO2)2O(R-mal)2][(MoO2)2O(S- mal)2]·4H2O 1 and (Him)2K6[(MoO2)4O3(R-mal)2][(MoO2)4O3(S-mal)2]·8H2O 2. Complex 1 belongs to the monoclinic system, space group C2/c with a = 14.8637(3), b = 6.9544(1), c = 19.6783(5) A, β = 100.081(2)°, V= 2002.70(7)A3, Mr = 1452.88, Z= 2, F(000) = 1416, T= 173 K, Dc = 2.409 g/cm3, μ(MoKa) = 2.167, R = 0.0283 and wR = 0.0733.2 is of triclinic system, space group P1 with a = 8.7707(2), b = 9.3310(3), c = 17.9093(7) A, α = 83.781(3), β = 85.626(2), γ= 84.822(2)°, V = 1447.84(8) A3, Mr = 2160.68, Z = 1, F(000) = 1048, T= 173 K, Dc = 2.478 g/cm3, μ(MoKα) = 2.230, R = 0.0234 and wR = 0.0584.1 is the first isolated dinuclear molybdenum(Ⅵ) malato complex in 1:1 molar ratio. The molybdenum atoms in the two complexes are six-coordinated in an approximately octahedral geometry. Two malates coordinate tridentately with the Mo atom via their α-alkoxy, α-carboxy and α-carboxy groups in 1 and 2. β-Carboxy group in 2 further links with the other two Mo atoms to give a tetrameric unit. The solution 1H and 13C NMR spectra indicate that dimeric malate molybdenum in 1 dissociates partly in solution and exists in an equilibrium with tetrameric species, while 2 is stable and retains its tetrameric structure without any dissociation.