Synthesis and crystal structures of (C8h8)Nd(C5H9C5H4) (THF)2 and [(C8H8)Gd(C5H9C4H4(THF)][(C8H8)GD(C5H9C5H4(THF)2]

LnCl₃ (Ln=Nd, Gd) reacts with C₅H₉C₅H₄Na (or K₂C₈H₈) in THF (C₅H₉C₅H₄ = cyclopentylcyclopentadienyl) in the ratio of 1 : to give (C₅H₉C₅H₄)LnCl₂(THF)_n (orC₈H₈)LnCl₂(THF)_n], which further reacts with K₂C₈H₈ (or C₅H₉C₅H₄Na) in THF to form the litle complexes. If Ln=Nd the complex (C₈H₈)Nd(C₅H₉C₅H₄)(THF)₂ (a) was obtained: when Ln=Gd the 1 : 1 complex [(C₈H₈)Gd(C_%H₉)(THF)][(C₈H₈)Gd(C₅H₉H₄)(THF)₂] (b) was obtained in crystalline form.

The crystal structure analysis shows that in (C₈H₈)Ln(C₅H₉C₅H₄)(THF)₂ (Ln=Nd or Gd), the Cyclopentylcyclopentadieny (η⁵), cyclooctatetraenyl (η⁸) and two oxygen atoms from THF are coordinated to Nd³⁺ (or Gd³⁺) with coordination number 10.

The centroid of the cyclopentadienyl ring (Cp′) in C₅H₉C₅H₄ group, cyclooctatetraenyl centroid (COTL) and two oxygens (THF) form a twisted tetrahedron around Nd³⁺ (or Gd³⁺). In (C₈H₈)Gd(C₅H₉C₅H₄)(THF), the cyclopentyl-cyclopentadienyl (η⁵), cyclooctatetraenyl (η⁸) and one oxygen atom are coordinated to Gd³⁺ with the coordination number of 9 and Cp′, COT and oxygen atom form a triangular plane around Gd³⁺, which is almost in the plane (dev. -0.0144 Å).     

Singlet-triplet energy separations in divalent five-membered cyclic conjugated C5H3X, C4H3SiX, C4H3GeX, C4H3SnX, and C4H3PbX (X = H, F, Cl, and Br)

Singlet-triplet energy gaps in cyclopenta-2,4-dienylidene, as well as its 2- or 3-halogenated derivatives, are compared and contrasted with their sila, germa, stana, and plumba analogues; at HF/6-31G* and B3LYP/ 6-311++G(3df, 2p) levels of theory. Energy gaps (ΔG_t-s), between triplet (t) and singlet (s) states, appear linearly proportional to: (i) the size of the group 14 divalent element (M = C, Si, Ge, Sn and Pb), (ii) the angle ∠C-M-C, and (iii) the ΔG_(LUMO-HOMO) of the singlet state involved. The magnitude of ΔG_t-s, for each 2- and/or 3-substituted species studied, increases with an order of: carbenes < silylenes < germylenes < stanylenes < plumbylenes. This order reverses for the barriers of the ring puckering. The puckering occurs with more ease for every singlet, compared to its corresponding triplet form.Regardless of the group 14 element (M) employed, every 3-halo-substituted species is more stable than the corresponding 2-halo-substituted isomer. For M = Pb, Sn and/or Ge; 3-halo-substituted species have higher ΔG_t-s than their corresponding 2-halo-substituted analogues. For M = Si, similar ΔG_t-s are found for 2- and 3-halogenated isomers. For M = C, 3-halo-substituted species have lower ΔG_t-s than their corresponding 2-halo-substituted analogues.Every cyclic singlet has a larger ∠C-M-C angle, than its corresponding cyclic triplet state, except for 3-halosilacyclopenta-2,4-dienylidenes where triplet has a larger ∠C-M-C angle than its corresponding singlet state.     

Thermodynamic study of systems with lower critical solution temperatures: H2O + (C2H5)3N,D2O + (C2H5)3N

Chand, A., McQuillan, A.R. and Fenby, D.V., 1979. Thermodynamic study of systems with lower critical solution temperatures: H₂O + (C₂H₅)₃N, D₂O + (C₂H₅)₃N. Fluid Phase Equilibria, 2: 263–274.Molar excess enthalpies and molar excess volumes are reported for the systems H₂O + (C₂H₅)₃N and D₂O + (C₂H₅)₃N at temperatures below and above their lower critical solution temperatures. The molar excess enthalpies are slightly less exothermic for the D₂O system. The molar excess volumes of the H₂O and D₂O systems are within experimental error of one another. Compositions of conjugate solutions estimated from the calorimetric and volumetric measurements agree with those obtained from published liquid—liquid phase diagrams.     

DFT studies on coplanar poly-cage cubanes C8+4nH8 (n=1–5)

Coplanar poly-cage cubanes C_8+4nH₈ (n=1–5) have been studied using DFT method at B3LYP/D95** level of theory, vibrational frequencies of these molecules have been calculated at B3LYP/D95** level of theory and spectrums of these molecules have been simulated else, heats of formation of these molecules also have been estimated here.     

脉冲光声量热法测量n-C4H9Co(Salen)H2O的Co-C键离解能

By using photoacoustic calorimetry, a photoacoustic measurement system is applied to determine the Co-C bond dissociation energy of n C₄H₉Co(Salen)H₂O, which is 116±8kJ·mol^-1. This value is in agreement with the activation enthalpy of the Co-C bond homolytic cleavage reaction that obtained by the kinetic method.     

Thermal behaviour of two new salts of malonic acid: Cu(C3H2O4)·4H2O and Cu(NH4)2(C3H2O4)2

Two new salts of malonic acid have been prepared: the copper(II) malonate tetrahydrate and the copper(II)-ammonium double malonate. Their study by thermal analysis (TG and DTA) leads to the following results:Cu(C₃H₂O₄)·4H₂O: the dehydration is rather complex and it is only under careful conditions that an intermediate hydrate Cu(C₃H₂O₄)·3H₂O could be traced. At about 170°C the dehydration is not ended (the salt holds yet about 0.15H₂O) and the anhydrous salt occurs only at about 240°C. It decomposes immediately leading to residues the composition of which depends upon the surrounding atmosphere; the part played by the gas given off is discussed.Cu(NH₄)₂(C₃H₂O₄)₂: this salt melts and decomposes simultaneously at about 190°C. During the decomposition the copper nitride Cu₃N forms as intermediate compound (as well as copper metal). Concerning the final residues of the decomposition the results and the conclusions are the same as the ones of the previous case.     

Hydrothermal synthesis and characterization of a new 3D vanadium(III) phosphite (C4H8N2H4)0.5(C4H8N2H3)[V4(HPO3)7(H2O)3]1.5H2O

A new vanadium(III) phosphite, (C₄H₈N₂H₄)_0.5(C₄H₈N₂H₃)[V₄(HPO₃)₇(H₂O)₃]1.5H₂O, has been synthesized hydrothermally by using V₂O₅, H₃PO₃ as reactants, piperazine as the structure-directing agent. The as-synthesized product was characterized by powder X-ray diffraction, IR spectroscopy, inductively coupled plasma analysis, thermogravimetric analysis, and SQUID magnetometer. Single-crystal X-ray diffraction analysis shows that the title compound crystallized in the trigonal space group (No. 165) with the parameters: , , and Z=4. Its structure is built up by alternation of octahedral VO₆ or VO₅(H₂O) and pseudo-pyramidal HPO₃ units to form infinite 2D layers, and these layers are interconnected by sharing vertex-oxygen with octahedral VO₆ units to generate a 3D open-framework structure with 12-membered ring channels in a and b directions, respectively, where there exist entrapped diprotonated and mono-protonated piperazine cations, and water molecules. Magnetic measurement indicates that paramagnetic behavior is observed down to 4 K.     

Vibrational energy transfer in cyclopropane (C3H6)

Infrared laser-induced fluorescence measurements of vibrational relaxation in cyclopropane are presented. Following laser excitation of the CH-stretch vibrations υ₆ and υ₈ time-dependent fluorescence signals from υ₁₀ and υ₇/υ₁₁ were recorded. Activation and deactivation rate constants for C₃H₆C₃H₆ collisions were found for υ₁₀ and υ₇/υ₁₁. A simplified model for the vibrational relaxation of cyclopropane is discussed.     

C2H3Cl分子团簇内部离子-分子反应产生C4H5Cl+的研究

用同步辐射对（Ｃ２Ｈ３Ｃｌ）２分子团簇进行了光电离研究，发现该团簇内部发生了离子－分子化学反应，生成了十分稳定的反应产物Ｃ４Ｈ５Ｃｌ＾＋，不再是ｖａｒｄｅｒＷａａｌｓ弱键络合物，本文对反主尖机理进行了初步探讨。     

Reactions of C2(a 3πu) with CH4, C2H2, C2H4, C2H6, and O2 using multiphoton UV excimer laser photolysis

C₂(a ³π_u) disappearance rate constants of 1.44, 0.96, 0.0296, 0.0130 and < 10^?6(x10^?10cm³s^?1) are reported for reactions with C₂H₄, C₂H₂, O₂, C₂H₆, and CH₄, respectively at 298 K. C₂(a ³π_u) fragments are generated by multiphoton ArF excimer laser photodissociation at C₂H₂, and monitored by dye laser induced fluorescence. Arguments are presented which favor chemical reactions over the C₂(a ³π_u) → (X ¹σ⁺_g) quenching channel. C₂ + C₂H₂ represents the one possible exception to the reactive channel.     

Evidence for the distortion of C2H4 and C2H2 chemisorbed on W(100)

The adsorption of C₂H₄ on W(100) has been studied by ultraviolet photoelectron spectroscopy with hν = 21.22 eV. The spectrum measured after in initial saturation exposure at 80 K exhibits structure which correlates well with energy levels recently calculated by Demuth and Eastman (DE) for sp³ rehybridized C₂H₄. Dehydrogenation of the adsorbate, either by subsequent heating to 295 K or direct adsorption at 295 K, yields a spectrum which correlates with DE's calculation for sp² rehybridized C₂H₂. These results suggest that C₂H₄ and C₂H₂ may be distorted from their planar and linear structures respectively and that the CC bonds on these molecules are stretched by adsorption on W(100). Qualitative arguments suggest that the bonding site for both melecules is directly over a W atom and that the Dewar—Chatt model for πd bonding in organometallic compounds is applicable.     

Synthesis and crystal structure of Ir(C2H4)2(C5H7O2)

We report a new synthesis and characterization of Ir(C₂H₄)₂(C₅H₇O₂) [(acetylacetonato)-bis(η²-ethene)iridium(I)], prepared from (NH₄)₃IrCl₆ · H₂O in a yield of about 45%. The compound has been characterized by X-ray diffraction crystallography, infrared, Raman, and NMR spectroscopies and calculations at the level of density functional theory. Ir(C₂H₄)₂(C₅H₇O₂) is isostructural with Rh(C₂H₄)₂(C₅H₇O₂), but there is a substantial difference in the ethylene binding energies, with Ir-ethylene having a stronger interaction than Rh-ethylene; two ethylenes are bound to Ir with a binding energy of 94 kcal/mol and to Rh with a binding energy of 70 kcal/mol.     

Etude vibrationnelle des composes (C4H4P)Mn(CO)3 et [C4H2(CH3)2P]Mn(CO)3 et calcul du champ de force du cycle C4H4P complexe

The Raman and infrared spectra (4000200 cm^?1) of (C₄H₄P)Mn(CO)₃ and (C₄D₄P)Mn(CO)₃, and of [C₄H₂(CH₃)₂P]Mn(CO)₃ and [C₄D₂(CH₃)₂P]Mn(CO)₃ in the liquid and solid states (10–400 K) have been investigated. A complete vibrational assignment is proposed and valence force fields of the (C₅H₅) and (C₄H₄P) cycles are compared. From these results, it is clearly shown that the (C₄H₄P) rings are more electrophilic and weaker π-electron donors than (C₅H₅) rings, this is in agreement with their chemical behavior.     

Determination of molecular line parameters for acrolein (C3H4O) using infrared tunable diode laser absorption spectroscopy

Acrolein (C₃H₄O) molecular line parameters, including infrared (IR) absorption positions, strengths, and nitrogen broadened half-widths, must be determined since they are not included in the high resolution transmission (HITRAN) molecular absorption database of spectral lines. These parameters are required for developing a quantitative analytical method for measuring acrolein in a single puff of cigarette smoke using tunable diode laser absorption spectroscopy (TDLAS). The task is complex since acrolein has many highly overlapping infrared absorption lines in the room temperature spectrum and the cigarette smoke matrix contains thousands of compounds. This work describes the procedure for estimating the molecular line parameters for these overlapping absorption lines in the wavenumber range (958.7–958.9 cm⁻¹) using quantitative reference spectra taken with the infrared lead-salt TDLAS instrument at different pressures and concentrations. The nitrogen broadened half-width for acrolein is 0.0937 cm⁻¹ atm⁻¹ and to our knowledge, is the first time it has been reported in the literature.     

Synthesis and X-ray structure of the Mo(VI) species Mo4O12(C12H30N4S2)2(C3H7ON)n (n ≈ 2)

Dissolution of Mo₂O₅((CH₃)₂NCH₂CH₂NHCH₂CH₂S)₂ in dimethylformamide results in the formation of a species without coordinated sulphur, as indicated by ⁹⁵Mo NMR spectroscopy. Subsequent crystallization of this solution yielded the compound Mo₄O₁₂(C₁₂H₃₀N₄S₂)₂(C₃H₇ON)₂ which X-ray crystallography shows to consist of a novel Mo₄O₁₂ core, containing an eight-membered Mo₄O₄ ring with the two pairs of diagonal molybdenum atoms linked by disulphido-containing groups.     

(C5H5FeS1,55)4: Ein neuartiger vierkerniger Fe-S-Cluster in einer (C5H5FeS)4-Matrix

Ohne Zusammenfassung

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(C₅H₅FeSi_1.5)₄: A new quadrinuclear Fe-S cluster in a (C₅H₅FeS)₄ matrix

     

Structure des ions [C4H7O]+ obtenus par fragmentations du [1-methylcyclobutanol]

The mass spectra of metastable molecular and fragment ions demonstrate that the loss of CH₃^. from [1-methylcyclobutanol]^.+ leads competitively to three different ions: $\text{a}$ = protonated cyclobutanone; $\text{b}$ = [n-C₃H₇CO]⁺ and $\text{c}$ = protonated methylvinylketone.     

Magnetic investigation of Er(C2O4) (C2O4)·3H2O

Single crystal susceptibilities of Er(C₂O₄) (C₂O₄H)·3H₂O are reported over the 1.5–20 K interval, and EPR spectra at 4.2 K of Y (C₂O₄) (C₂O₄H·3H₂O doped with Er³⁺ are also reported. The susceptibilities follow the CurieWeiss law, with g_| = 12.97 ± 0.05, g_⊥ = 2.98 ± 0.05, θ_| = ?0.25 ± 0.05 K, and θ_⊥ = ?0.12 ± 0.05 K.