Thiacalix[3]pyridine produces a stable mononuclear rhodium(II) complex with mutual Jahn-Teller effect

Thiacalix[3]pyridine (Py3S3) consists of pyridines and bridging sulfur atoms producing a stable octahedral mononuclear Rh(II) complex [Rh(II)(Py3S3)2]2+ showing mutual Jahn-Teller effect, a metal based reversible redox couple of Rh(III/II) at 0.02 V vs. SCE and a g(perpendicular) > g(||) relationship in EPR measurements.     

Anomalously large formula unit volume and its effect on the thermal behavior of LiBF4

The crystal structure of LiBF4 has been determined by single-crystal X-ray diffraction measurements. LiBF4 crystallizes as a merohedral twin in the trigonal space group P3(1)21 with a=4.892(5) A, c=11.002(12) A, V=228.0(4) A3, and Z=3 at 200 K. The twin is generated by a 2-fold rotation about the [10] direction. The lithium cation is coordinated by four fluorine atoms in a distorted tetrahedral manner, wherein two Li-F distances of 1.862(5) and 1.846(5) A are observed. The formula unit volume (FUV=V/Z) of 77.9 A3 for LiBF4 at 298 K is considerably larger than 72.7 A3 for NaBF4 and 72.5 A3 for AgBF4, despite the smaller size of Li+, indicating loose ionic packing of LiBF4. The thermodynamic evaluation of the decomposition temperature for LiBF4 was performed using the empirical relationship between the standard entropy and the FUV obtained. The results indicate that the large FUV of LiBF4 contributes to its higher decomposition temperature compared to that of LiPF6.     

Efficient Emission of Ultraviolet Light by Solid State Organic Fluorophores: Synthesis and Characterization of 1,4-Dialkeny-2,5-dioxybenzenes

The design and development of organic luminophores that exhibit efficient ultraviolet (UV) fluorescence in the solid state remains underexplored. Here, we report that 1,4-dialkenyl-2,5-dialkoxybenzenes and 1,4-dialkenyl-2,5-disiloxybenzenes act as such UV-emissive fluorophores. The dialkenyldioxybenzenes were readily prepared in three steps from 2,5-dimethoxy-1,4-diacetylbenzene or 2,5-dimethoxy-1,4-diformylbenzene via two to four steps from 1,4-bis(diethoxyphosphonylmethyl)-2,5-dimethoxybenzene. The dialkenyldioxybenzenes emit UV light in solution (λ_em=350–387 nm) and in the solid state (λ_em=328–388 nm). In addition, the quantum yields in the solid state were generally higher than those in solution. In particular, the adamantylidene-substituted benzenes fluoresced in the UV region with high quantum yields (Φ=0.37–0.55) in the solid state. Thin films of poly(methyl methacrylate) doped with the adamantylidene-substituted benzenes also exhibited UV emission with good efficiency (Φ=0.27–0.45). Density functional theory calculations revealed that the optical excitation of the dialkenyldimethoxybenzenes involves intramolecular charge-transfer from the ether oxygen atoms to the twisted alkenyl-benzene-alkenyl moiety, whereas the dialkenylbis(triphenylsiloxy)benzenes were optically excited through intramolecular charge-transfer from the oxygen atoms and twisted π-system to the phenyl-Si moieties of each triphenylsilyl group.     

Halofluorination of alkenes with ionic liquid EMIMF(HF)2.3

Halofluorination of alkene by means of N-halosuccinimide and ionic liquid, 1-ethyl-3-methylimidazorium oligo hydrogenfluoride (EMIMF(HF)_2.3), was demonstrated. Various alkenes were converted into β-halo organofluorides in good yields after non-aqueous work-up.     

Hexafluoro-, heptafluoro-, and octafluoro-salts, and [MnF5n+1] (n = 2, 3, 4) polyfluorometallates of singly charged metal cations, Li-Cs, Cu, Ag, In and Tl

The AMF₆, A₂MF₇, A₃MF₈, AM₂F₁₁, AM₃F_l6 and AM₄F₂₁ compounds (A = Li, Na, K, Rb, Cs, Cu, Ag, In, Tl; M = P, As, V, Rh, Ru, Au, Pt, Ir, Os, Re, Sb, Mo, W, Nb, Ta, Bi) are reviewed.Some of the structural data of the AMF₆ compounds are based just on powder diffraction work from the middle of the last century. The crystal structure types of AMF₆ compounds have been re-classified in this review, based mainly on single crystal data. The crystal structure types of AMF₆ compounds can be classified into six main groups: LiSbF₆ type, NaSbF₆ type, structures of cubic APF₆ and AAsF₆ with orientational disorder of the anions, tetragonal KSbF₆ (T) types and similar structures, AgSbF₆ type and similar structures, and KOsF₆ type.Reported crystal structures of A₂MF₇, A₃MF₈, AM₂F₁₁, AM₃F_l6 and AM₄F₂₁ compounds are limited. K₂MF₇ (M = Nb, Ta) crystallizes in the monoclinic and K₂WF₇ in the orthorhombic crystal system. Among the A₃MF₈ compounds the complete crystal structure has been determined only for Na₃TaF₈, which is monoclinic. The only known examples of crystal structures of AM₂F₁₁ compounds are ASb₂F₁₁ (A = Ag, K, Cs). Crystals of KSb₂F₁₁ are orthorhombic and isostructural to AgSb₂F₁₁, while CsSb₂F₁₁ is monoclinic. CsSb₃F₁₆ is the only example of a structurally characterized AM₃F_l6 compound. Its crystals are orthorhombic. For the rest of the known A₂MF₇, A₃MF₈, AM₂F₁₁, AM₃F_l6 and AM₄F₂₁ compounds, only lattice parameters are known.     

A mild ring opening fluorination of epoxide with ionic liquid 1-ethyl-3-methylimidazorium oligo hydrogenfluoride (EMIMF(HF)2.3)

Ring opening fluorination of epoxides with hydrogen fluoride in ionic liquid 1-ethyl-3-methylimidazorium oligo hydrogenfluoride EMIMF(HF)_2.3 was demonstrated. This ionic liquid released hydrogen fluoride graduately to make mild conditions without oligomerization of epoxides.     

Some examples and the connection between cylindrical measures and measurable norms

In this paper, we construct an example of a cylindrical measure μ and a norm ‖·‖ such that ∥·∥ is μ-measurable by Dudley et al. and not μ-measurable by Gross and moreover is γ-measurable.     

Electronic and magnetic characteristics of polycyclic aromatic hydrocarbons with factorizable Kekulé structure counts

The Kekule? structure count (K) for some types of polycyclic aromatic hydrocarbons (PAHs), such as fluoranthene and perylene, can be factorized into the product of those for two or more aromatic subunits. The ring-current map for these PAHs placed in a perpendicular magnetic field exhibits a substantial localization on aromatic subunits. We found that such localization of π circulation is a characteristic of fairly small K-factorizable species in the neutral electronic state. Even in such a case, no single π molecular orbital (πMO) is associated with localized π circulation. Apparent localization of π circulation is caused by the superposition of currents induced by all occupied πMOs. π circulation is less localized in larger K-factorizable species.