The circular dichroism of the charge-transfer bands of M(bpy)2+3 (M = Re,Ru, Os)

The absolute configuration of (?)_D-Ru(bpy)₃(ClO₄)₂ has been determined to be the right-hand screw configuration Δ. CD spectra of M(bpy)²⁺₃ (M = Fe, Ru, Os) doped in a uniaxial host. Lattice lead to a new assignment of CD bands in the MLCT region. The CD arises from intrinsically allowed electronic and magnetic transition dipole moments, the latter coming from metal-centered transitions.     

M(bpy)2+3(M=Fe,Ru,Os)电子结构与相关性质

报导了对配合物Ｍ（ｂｐｙ）＾２＋３（Ｍ＝Ｆｅ,Ｒｕ,Ｏｓ）的量子化学密度泛函法研究的结果。Ｂ３ＬＹＰ／ＬａｎＬ２ＤＺ方法与基组的水平上进行计算,探讨Ｍ（ｂｐｙ）＾２＋３电子结构特征及相关性质,特别是中心原子对配合物的配位键长、光谱性质,电荷布局及化学稳定性等的影响规律,为该类配合物的合成,为分析光、电、催化作用机理提供理论参考。     

Optical absorption spectrum of excited ruthenium tris-bipyridyl (Ru(bpy)2+3)

The optical absorption spectrum of excited ruthenium tris-bipyridyl (Ru(bpy)²⁺₃) in the range of 244–500 nm is determined by applying the method of intensity dependence measurement.     

The electronic structure of Cu(ethanediimine)+2

Extended-Hückel and multiple-scattering Xα molecular orbital calculations are reported for the Cu(ethanediimine)⁺₂ complex. The results obtained are in agreement. From the calculated electronic transition energies, it is inferred that the lowest excited state is a B₂ state of metal-to-ligand charge-transfer type, confirming resonance Raman results.     

M(bpy)2+3(M=Fe,Ru,Os)电子结构与相关性质

报导了对配合物(M=Fe,Ru,Os)的量子化学密度泛函(DFT)法研究的结果.在B3LYP/LanL2DZ方法与基组的水平上进行计算,探讨的电子结构特征及相关性质,特别是中心原子对配合物的配位键长、光谱性质、电荷布居及化学稳定性等的影响规律,为该类配合物的合成,为分析光、电、催化作用机理提供理论参考.     

Influence of added salts on the cage escape yields in the photoredox quenching of Ru(bpy)2+3 excited states

The influence of electrolytes on the photoredox kinetics and cage escape yields of redox products (π_redox) in the quenching of Ru(bpy)^2+*₃ by methylviologen (MV²⁺), Tl^III and Hg^II have been investigated. For all three quenchers π_redox appears to be strongly dependent on the nature of the anion. Photoelectrochemical cells based on the latter systems are described.     

Photodissociation of the dimer ions Ar+2, Ne+2, and (CO2)+2

The tandem quadrupole photodissociation mass spectrometer has been used to study photodissociation reactions of Ar⁺₂, Ne⁺₂, and (CO₂)⁺₂. The cross sections for photodissociation of Ar⁺₂ exhibited a strong dependence on ion source pressure, varying from 2 × 10 ^?18cm² at 0.1 torr to 6 × 10^?19cm² at 0.5 torr. A large photodissociation cross section (2 × 10^?17cm² for the reaction (CO₂)⁺₂ → CO⁺₂+ CO₂ was observed at the red end of the visible spectrum (580–620 nm) suggesting that this may be an important reaction in CO₂ rich planetary ionspheres such as that of Mars.     

[M(bpy)3] (M = Fe,Ru, Os): New Crystalline Materials from the reductive electrocrystallization of [M(bpy)3](PF6)2

Reductive electrocrystallization at a constant current density (11.0–11.5 μA/cm²) of millimolar solutions of [M(bpy)₃](PF₆)₂, where M = Fe, Ru, or Os, and bpy = 2,2′-bipyridine in acetonitrile containing 0.1M Bu₄NPF₆ results in the formation of dark crystals on the Pt cathode. The crystals grow as long, thin, and shiny needles having a hexagonal cross section of 0.1–0.5 mm in diameter. Combustion microanalyses results are consistent with the composition for [Fe(bpy)₃], [Ru(bpy)₃], and [Os(bpy)₃]. In addition, the chromophores are conserved, as confirmed by recording both the electronic and the ¹H-NMR spectra after reoxidation of the electrocrystals in humid air. The spectra are identical to those for authentic samples of [Fe(bpy)₃]²⁺, [Ru(bpy)₃]²⁺, and [Os(bpy)₃]²⁺. A ratio of 2.0 ± 0.1 e^?/molecule is observed upon completion of the controlled potential electrolysis of a solution of [M(bpy)₃]²⁺, which results in the precipitation of a dark solid and the almost complete fading of the color of the original solution. Unexpectedly, the crystals do not exhibit an ESR signal. These data indicate the formation of novel materials, crystalline [Fe(bpy)₃], [Ru(bpy)₃], and [Os(bpy)₃].     

Cu(bpy)2+2与鸟嘌呤及鸟苷相互作用的研究

在中性磷酸盐缓溶冲液中，用电化学和荧光光谱法研究了Cu(bpy)²⁺₂与鸟嘌呤和鸟苷的相互作用。结果表明鸟嘌呤和鸟苷与Cu(bpy)²⁺₂的配位比均为1∶1，配位常数分别为4.62×10⁴ L/mol和1.96×10⁴ L/mol。紫外光谱电化学实验进一步表明，鸟嘌呤或鸟苷与Cu(bpy)²⁺₂发生了相互作用。     

二价钌有机螯合物Ru(dpphen)2+3与花生酸混合LB膜的结构及光谱特性

对不同组分的Ru(dpphen)     

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.     

Evidence for symmetry reduction in excited states of [Ru(bpy)3]+ and related compounds

Photoselection and other spectroscopic data for [Ru(bpy)₃]²⁺, [Ru(phen)₃]²⁺, [Ru(bpy)(py)₄]²⁺ and [Os(bpy)₃]²⁺ suggest that the emitting state for the tris compounds may be localized on a single ring.     

Ci calculations of the low lying electronic states of the radical SiH3, SiH+3 and SiH−3

SCF and CI calculations for the silicon-hydrogen compounds SiH₃, SiH⁺₃ and SiH^? with D_3h and C_3v geometries are carried out f     

Stabilization and electron spin resonance characterization of Ru(bpy)3 and Ru(bpy)3 by radiolysis of Ru(bpy)3 adsorbed on silica gel

Ru(bpy)₃³⁺, which is important in artificial photosynthetic systems due to its high reduction potential, is stabilized together with its counter anion, Ru(bpy)₃⁺, by radiolysis of Ru(bpy)₃²⁺ adsorbed on silica gel at 77 K. Both species are characterized by electron spin resonance.     

Structural, electronic, and acid/base properties of [Ru(bpy)2(bpy(OH)2)]2+ (bpy = 2,2'-bipyridine, bpy(OH)2 = 4,4'-dihydroxy-2,2'-bipyridine)

We have synthesized the complex [Ru(bpy)(2)(bpy(OH)(2))](2+) (bpy =2,2'-bipyridine, bpy(OH)(2) = 4,4'-dihydroxy-2,2'-bipyridine). Experimental results coupled with computational studies were utilized to investigate the structural and electronic properties of the complex, with particular attention paid toward the effects of deprotonation on these properties. The most distinguishing feature observed in the X-ray structural data is a shortening of the CO bond lengths in the modified ligand upon deprotonation. Similar results are also observed in the computational studies as the CO bond becomes double bond in character after deprotonating the complex. Electrochemically, the hydroxy-modified bipyridyl ligand plays a significant role in the redox properties of the complex. When protonated, the bpy(OH)(2) ligand undergoes irreversible reduction processes; however, when deprotonated, reduction of the substituted ligand is no longer observed, and several new irreversible oxidation processes associated with the modified ligand arise. pH studies indicate [Ru(bpy)(2)(bpy(OH)(2))](2+) has two distinct deprotonations at pK(a1) = 2.7 and pK(a2) = 5.8. The protonated [Ru(bpy)(2)(bpy(OH)(2))](2+) complex has a characteristic UV/Visible absorption spectrum similar to the well-studied complex [Ru(bpy)(3)](2+) with bands arising from Metal-to-Ligand Charge Transfer (MLCT) transitions. When the complex is deprotonated, the absorption spectrum is altered significantly and becomes heavily solvent dependent. Computational methods indicate that the deprotonated bpy(O(-))(2) ligand mixes heavily with the metal d orbitals leading to a new absorption manifold. The transitions in the complex have been assigned as mixed Metal-Ligand to Ligand Charge Transfer (MLLCT).     

Synthesis and crystal structure of (ThCu3)(Mn3+2Mn4+2)O12, a new ferrimagnetic perovskite-like compound

Single crystals of [ThCu₃](Mn³⁺₂Mn⁴⁺₂]O₁₂, a ferrimagnetic perovskite-like compound, have been synthesized by hydrothermal conditions at 600°C and 2 kbar. They have been found to be cubic, of space group Im3, with a = 7.359 Å, and isostructural with [NaMn₃](Mn³⁺₂Mn⁴⁺₂)O₁₂. The crystal structure has been refined by single-crystal X-ray diffraction data. The Th⁴⁺ cations are surrounded by slightly distorted icosahedra; the ThO distance is 2.556 Å. The Cu²⁺ cations are also surrounded by 12 oxygens, which are arranged as three mutually perpendicular rectangles of different size, the smallest and the largest of which are almost squares. The three sets of CuO distances are 1.973, 2.800, and 3.238 Å. The octahedral MnO distance is 1.950 Å. A test based on neutron diffraction powder data indicated that the square sites are occupied by only the Cu²⁺ cations.     

羰基原子簇化合物M3(CO)12(M=Fe,Ru,Os)的激光解离研究

在自制的仪器上以冲激光溅射铁、钌、锇的三核羰基原子簇化合物。由原位质谱观察和分析溅射产生的正负离子。比较了解离碎片及分布发现羰基锇原子簇化合物具有特殊的结构稳定性。它们不仅具有很强的金属键,而且锇与羰基分子还形成了很强的配位键。     

Zero-phonon and vibronic structure of [Os(bpy)32+ doped into single-crystal [Ru(bpy)3](ClO4)2

Highly resolved emission and absorption spectra of [Os(bpy)₃]²⁺, doped into single-crystal [Ru(bpy)₃](ClO₄)₂, are reported. Our investigations, at low temperatures (2⩽T⩽50 K) and high magnetic fields ( 0⩽H⩽6 T ), lead to the following results: The three lowest excited states of [Os(bpy)₃]²⁺ in this matrix are identified from zero-phonon transitions lying at 14169 ± cm⁻¹ (line I), 14230± cm⁻¹ (line II), and 14380 ± 2 cm⁻¹ (line III). These transitions are found at the same energies (within the experimental error of ± 2 cm⁻¹) in absorption and emission. The extinction coefficients of II and III are ≈ 10³ XXX mol⁻¹ cm⁻¹ while the transition |0>→ |I> (line I) is strongly forbidden. However, under high magnetic fields this absorption line grows in due to a mixing of |I> with |II>. A large number of vibronic peaks is identified in the emission spectra. The corresponding vibrational modes are compared to Raman and IR data of [Ru(bpy)₃]²⁺ and [Os(bpy)₃]²⁺. Several distinct modes couple more strongly to the transition from the lowest excited state |I>, others to the transition from |II>, as is shown by investigating the magnetic field dependence of the emission spectra.     

Anomalous electronic energy partitioning in Mg*(3p) + (F2, Cl2) and Ca*(3P) + Cl2 reactions

Absolute cross sections were measured for beam attenuation, MX⁺(¹Σ_g⁺) chemiionization and MX(A²Π) chemiluminescence. The latter disagree strikingly with predictions based on adiabatic correlations. Information theoretic analysis shows some channels to be statistically, other highly non-statistically populated. A qualitative MO model is in accord with these findings.