Neutron scattering study of the reorientational motions in Cr(CO)3(η6C6H6) and Mn(CO)3(η5C5H5)

Incoherent quasi-eleastic neutron scattering experiments: using different resolutions and a wide Q range, have been performed on polycrystalline samples of Cr(CO)₃(η⁶C₆H₆) and Mn(CO)₃(η⁵C₅H₅) in the 280–320 K temperature range. It is shown that aromatic rings are involved into a reorientational process characterized by an activation energy of ≈ 16 kJ mol^?1 and by correlation times of the order of 2 × 10^?11 s and 5 × 10^?11 s at 300 K for C₆H₆ and C₅H₅ rings respectively. Experimental elastic incoherent structure factors are in agreement with the 2π/6 and 2π/5 jump models and the fitted spectra confirm these models. From a comparison with heat-capacity results we conclude that M(CO)₃ groups are fixed during the reorientational process. Finally a comparison with literature data is presented.     

Kristall- und molekülstruktur von hexaphenyldistannylselenid (C6H5)3SnSeSn(C6H5)3

The crystal and molecular structure of hexaphenylditin selenide (C₆H₅)₃SnSeSn(G₆H₅)₃ was determined by X-ray diffraction data and was refined to R  0.055. The compound is monoclinic, space group P2₁, with a  9.950(4), b  18.650(7), c  18.066(6) Å, β  106.81(4)°, Z  4. The two molecules in the asymmetric unit differ slightly in their conformations, both having approximate C₂ symmetry. Bond lengths and angles are: SnSe 2.526 (2.521(3) ? 2.538(3)) Å; SnC 2.138 (2.107(16)?2.168(19)) Å; SnSeSn 103.4(1)°, 105.2(1)°. There are only slight angular distortions at the SnSeC₃ tetrahedra (SeSnC angles: 104.3(5)?114.8(4)°). The bond data indicate essentially single bonds around the Sn atoms.     

Kristall-und molekülstrukturen zweier modifikationen de hexaphenyldigermylsulfids (C6H5)3GeSGe(C6H5)3

en Two differnt crystal modifications of hexaphenyldigermanium sulfide (C₆H₅GeSGe(C₆H₅)₃ (I and II were obtained by crystallization from hot benzene/methanol or form ethanol at 20°C. Single crystal X-ray structural analyses for both I (low temperature data at ?130°C) and II (at 20°C) (I, R = 0.046; II, R = 0.048) were performed. I is monoclinic, P2¹/c, with a = 11.020(3), b = 15.473(3), c 18.606(3) »,π = 106.92(2)°, Z = 4; II is orthorhombic, P2₁2₁2₁, with a = 2.617(2), b = 17.345(3), c = 18.408(3) », Z = 4.The molecules have different conformeric structures with respect to a rotation of the (C₆H₆)₃Ge groups around the Ge bonds with very similar bond lenghts and angles. Bond data for I(II) are: GeS 2.212(1) and 2.261(1) » (2.227(2) and 2.240(2) »); GeC 1.933(4) ? 1.971(4), mean 1.945(5) » (1.931(7)?1.954(7), mean 1.943(4) »); GeSGe 111.2(1)° (110.7(1)°). The Ge bond lenghts are comparable to those in thiogermanates and do not indicate significant π-bond contributions.     

Ein fünffach koordinierter ionischer zirkonium(IV)-komplex mit der (π-C5H5)2ZrIV-Baueinheit: [(π-C5H5)2Zr(H2O)3]2+(CF3SO3−)2·THF

The ionic complex [(π-C₅H₅)₂Zr(H₂O)₃]²⁺(CF₃SO₃^?)₂·THF, which corresponds to the 18-electron rule, is formed in the reaction of (π-C₅H₅)₂Zr(CF₃SO₃)₂(THF) with H₂O in tetrahydrofuran. It crystallizes in the hexagonal space group P6₃ with Z = 6 and unit cell dimensions at ? 100°C of a 21.945(5) and c 8.711(3) Å. The geometry of the (π-C₅H₅)₂Zr moiety (length of the vectors between Zr and the C₅ ring centroids: 2.210 and 2.193 Å; angle between these vectors: 129.0°; angle between the C₅ ring normals: 128.3°) agrees with that of neutral, four-coordinate (π-C₅H₅)₂ZrX₂ compounds. The three H₂O ligands lie in the plane that bisects the angle between the C₅ ring planes. The ZrO distances are 2.239(7), 2.195(7), and 2.261(7) Å. The CF₃SO₃^? anions and the THF molecule of crystallization are packed around the complex cation in such a way that their oxygen atoms point towards the H₂O ligands. The CF₃ sides of the anion, on the other hand, are clustered together so as to produce hydrophobic domains in the crystal structure.     

Hydrothermal synthesis, crystal structure, and thermal analysis of a Novel trinuclear manganese complex: Mn3(C12H8N2)2(C10H11O5)6

A novel trinuclear manganese(II) complex, Mn₃(C₁₂H₈N₂)₂(C₁₀H₁₁O₅)₆ (I), has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction. The crystal belongs to the monoclinic system, space group P2₁/n, with cell parameters a = 12.1935(7), b = 19.0249(11), c = 18.0515(10)?, β = 105.0430(10)°, V = 4044.1(4)?³, Z = 2. Two of the three manganese atoms in the crystal structure are crystallographically equivalent and adopt N₂O₄ coordination mode, whereas the remaining manganese atom adopts O₆ coordination mode, which forms a nearly regular octahedron. The experimental result of thermal analysis shows that complex I remains stable below 300°C.     

Temperature dependence of the reaction rate constants for O(3P) atoms with C2H4, C3H6 and NO(M = N2O), determined by a modulation technique

Rate constants for the reaction of O(³P) atoms with C₃H₄, C₃H₆ and NO(M = N₂O) have been measured over the temperature range 300–392°K using a modulation-phase shift technique. The Arrhenius expressions obtained are:C₂H₄, k₂ = 3.37 × 10⁹ exp[?(1270 ± 200)/RT]liter mole^?1 sec^?1,C₃H₆, k₂ = 2.08 × 10⁹ exp[?(0 ± 300)/RT]liter mole^?1 sec^?1,NO(M = N₂O), k₁ = 9.6 × 10⁹ exp[(900 ± 200/RT]liter² mole^?2 sec^?1.These temperature dependencies of k₂ are in good agreement with recent flash photolysis-resonance flourescence measurements, although lower than previous literature values.     

Synthesis, Characterization, Luminescence, and Electrochemistry of New Tetranuclear Gold(I) Amidinate Clusters: Au4[PhNC(Ph)NPh]4, Au4[PhNC(CH3)NPh]4, and Au4[ArNC(H)NAr]4

The syntheses and the X-ray structures of the tetranuclear gold(I) benzamidinate, Au₄[PhNC(Ph)NPh]₄, and the tetranuclear gold(I) acetamidinate, Au₄[PhNC(CH₃)NPh]₄, clusters are reported. The clusters are produced by the reaction of the sodium salt of an amidine ligand with the gold precursor Au(THT)Cl in a (1:1) stoichiometry. The average Au...Au distance between adjacent Au(I) atoms is ∼2.9 ?, typical of compounds having an aurophilic interaction. The four gold atoms are arranged in a square (Au...Au...Au... = 88–91°) in the acetamidinate and in a distorted square (Au...Au...Au... = 82–97°) in the benzamidinate derivative. Electrochemical oxidation of the tetranuclear complex Au₄[PhNC(Ph)NPh]₄ show three reversible waves at 0.87, 1.19, 1.42 V vs. Ag/AgCl at a scan rate of 100 mV/s in CH₂Cl₂ similar to the three reversible waves seen before from the tetranuclear complexes Au₄[ArNC(H)NAr]₄, Ar = C₆H₄-4-OMe, Ar = C₆H₄-4-Me, and Ar = C₆H₃-3,5-Cl. A summary of the chemistry of the tetranuclear Au(I) amidinate complexes Au₄[ArNC(H)NAr]₄, Ar = C₆H₄-4-OMe, C₆H₃-3,5-Cl, C₆H₄-4-Me, C₆H₄-3-CF₃, C₆F₅, C₁₀H₇ also is presented. The tetranuclear clusters Au₄[ArNC(H)NAr]₄, Ar = C₆H₄-4-OMe, Ar = C₆H₄-3-CF₃, Ar = C₆H₄-4-Me and Ar = C₆H₄-3,5-Cl are the first tetranuclear gold(I) cluster species from group 11 elements to show fluorescence at room temperature. The lifetimes of the naphthyl and trifluoromethylphenyl complexes are in the millisecond range indicating phosphorescent processes. Recently it has been shown that Au₄[ArNC(H)NAr]₄ are very effective catalysts upon calcination for room temperature CO oxidation. Congratulations to Dieter Fenske, a superb synthetic chemist with exceptional talents in cluster chemistry, on the occasion of his 65th birthday.     

Synthesis of π-(arene)metallocarboranes containing iron and ruthenium. Crystal structure of 3,1,2-(η6-1,3,5-(CH3)3C6H3)FeC2B9H11

The reaction of bis(arene)iron(II) salts (arene = mesitylene or hexamethylbenzene) or benzenedichlororuthenium(II) dimer with Tl[3,1,2-TlC₂B₉H₁₁] in THF produces neutral, air-stable π-(arene)(Fe, Ru)C₂B₉H₁₁ complexes in low or moderate yields. The metallocarboranes are formal analogues of [π-(arene)Fe, Ru)ⁿ⁺(C₅H₅)] species, and a single crystal X-ray structure of the title compound has established the closo sandwich geometry expected for the molecule on the basis of electron counting rules. The carborane cage was found to be disordered in the crystal but the essential features of the molecular geometry were not obscured. The mesitylene is symmetrically bound to the iron, and the Fe-arene (centroid) distance of 1.60 Å is similar to that found in the previously-characterized [(CH₃)₆C₆]Fe^I(C₅H₅) complex, despite the difference in the metal electronic configurations (d⁶ vs d⁷) and the change from the B₉C₂H₁₁^2? cage to C₅H₅^?. Crystals of 3,1,2-(η⁶-1,3,5-(CH₃)₃C₆H₃)FeC₂B₉H₁₁ are orthorhombic, space group Pn2₁a, with a = 12.638(4), b = 12.432(4), c = 9.686(3) Å.     

X-ray crystal analysis of tricyclohexyltin trifluoroacetate and Mössbauer data for (cyclo-C6H11)3SnO2CR′ (R′ = CH3, CH2CL,CHCL2, CCl3 and CF3)

The halogenocarboxylates (cyclo-C₆H₁₁)₃SnO₂CR′, (R′ = CH₃, CH₂Cl, CHCl₂, CCl₃ and CF₃) have been prepared, and characterized by Mössbauer and IR spectroscopy. The crystal structure of (cyclo-C₆H₁₁)₃SnO₂CCF₃ has been determined by X-ray analysis. The crystals are orthorhombic, space group Pcmn, with unit cell parameters a 14.390 ± 0.004, b, 13.427 ± 0.004, c 11.516 ± 0.003 Å. The structure was resolved by Patterson methods and refined to an R value of 0.147. The coordination about the tin atom can be considered distorted trigonal-pyramidal or distorted tetrahedral. Mössbauer data are explained in terms of distortions of bond angles about the tin atom.     

Synthesis and crystallographic characterization of a dicyclopentadienylvanadium alkynide complex: (C5H5)2VCCC(CH3)3

(C₅H₅)₂VCl reacts with LiCCC(CH₃)₃ to form (C₅H₅)₂VCCC(CH₃)₃ which was characterized by spectroscopic, analytical, and crystallographic methods. The complex crystallizes from pentane at 0°C as a monomer in the orthorhombic space group Pnma with four molecules in a unit cell of dimensions a 9.075(3), b 9.807(3), c 16.444(5) Å. Full-matrix least-squares refinement based upon 1300 nonzero intensity data converged to a final conventional R factor of 0.060. The molecule has a mean VC₅H₅-ring centroid distance of 1.941 Å with 146.6° ring centroid-V-ring centroid angle. The vanadium alkynide carbon distance is 2.075(5) Å.     

Synthese und eigenschaften neur kupfer- und gold-komplexe des typs C5H5MPR3, C5Me5MPR3 und R″C2MPR3 (M = Cu,Au) sowie die kristallstruktur von C5H5AuPPr3i

The complexes C₅H₅CuPR₃ (R = Me, Prⁱ), C₅H₅AuPR₃ (R = Me, Prⁱ), C₅Me₅CuPR₃ (R = Me, Prⁱ, Ph) and C₅Me₅AuPR₃ (R = Prⁱ, Ph) are prepared from [ClCuPR₃]_n or ClAuPR₃ and LiC₅H₅ (TlC₅H₅) or LiC₅Me₅, respectively. According to the ¹H and ¹³C NMR spectra, the cyclopentadienyl and pentamethylcyclopentadienylgold compounds are fluxional in solution. The X-ray crystal structure of C₅H₅AuPPr₃ⁱ has been determined at ?120°C. The gold atom is in a linear arrangement (PAuC(1) = 177.0(2)°) and primarily σ-bonded to the cyclopentadienyl ring which shows a weak “slip distortion” toward a η³-mode of coordination. The complexes C₅R′₅AuPR₃ (R′ = H, Me) and C₅Me₅CuPPr₃ⁱ react with 1-alkynes such as C₂H₂, HC₂Ph and HC₂CO₂Me to form alkinylgold and copper compounds R″C₂MPR₃. They have been characterized by IR, UV and NMR (¹H, ¹³C, ³¹P) spectroscopy.     

1-Allyl derivatives: Synthesis and crystal structures for [(NH2C5H4N(C3H5))2Cu3Cl3(NO3)2] and [C9H7N(C3H5)Cu(NO3)2]

1-Allyl-4-aminopyridinium chloride reacts with Cu(NO₃)₂ · 3H₂O in an ethanolic solution under the conditions of ac electrochemical synthesis at copper electrodes to form crystals of compound [(NH₂C₅H₄N(C₃H₅))₂Cu₃Cl₃(NO₃)₂] (I). The crystals of compound I are monoclinic: space group P2₁/c, Z = 4, a = 25.770(7), b = 7.230(4), c = 12.505(5) ?, β = 92.58(3)°, V = 2328(2) ?³. The direct interaction of 1-allylquinolinium nitrate with Cu(NO₃)₂ · 3H₂O in a methanolic solution in the presence of metallic copper yields crystals of compound [C₉H₇N(C₃H₅)Cu(NO₃)₂] (II). The crystals of compound II are triclinic: space group P , a = 6.756(3), b = 8.391(4), c = 12.489(5) ?, α = 77.18(3)°, β = 89.48(4)°, γ = 73.32(3)°, V = 662.0(5) ?³. The structure of compound I is built of infinite linear anions: polymeric fragments {(NH₂C₅H₄N(C₃H₅))₂Cu₃Cl₃(NO₃)₂} _n . Each of two copper atoms (Cu(1) and Cu(2)) π-coordinates the C=C bonds of the allyl groups of the 1-allyl-4-aminopyridinium cations, the oxygen atom of the nitrate ions, and two chlorine atoms. The third copper atom Cu(3) is linearly linked with two chlorine atoms. Particular polymeric fragments are additionally joined by the N-H…O, C-H…O, C-H…Cl hydrogen bonds. The crystal structure of compound II is built-up of the isolated L₂Cu₂(NO₃)₄ fragments (L is the 1-allylquinolinium cation). The metal atom is localized in the trigonal pyramidal coordination environment of three oxygen atoms of the nitrate ions and of the C=C bond of the allyl group of the cation. The particular L₂Cu₂(NO₃)₄ fragments are additionally joined by the C-H…O hydrogen bonds. Original Russian Text ? A.V. Pavlyuk, T. Lis, M.G. Mys’kiv, 2009, published in Koordinatsionnaya Khimiya, 2009, Vol. 35, No. 6, pp. 458–462.     

Electron scattering differential cross sections for C2H2, C2H4, and C2H6 by gas phase electron diffraction - binding effects

Experimental differential cross sections for 40 keV electrons scattered by C₂H₂, C₂H₄ and C₂H₆ molecules were measured using the gas electron diffraction method in the range of the scattering variable s from s = 1 A^?1 to s = 30 A^?1. The differential cross sections for neon were also measured and compared with calculated differential cross sections to calibrate the diffractograph. Experimental differential cross sections show significant deviations with respect to theoretical differential cross sections calculated from the Debye-Ehrenfest model, mainly in the range of small scattering angles. The observed differences are connected to chemical binding effects. From the experimental data, an estimation of the binding energy was carried out. The deduced values: ?0.58 ± 0.20 au for C₂H₂, ?0.94 ± 0.30 au for C₂H₄ and ?1.23 ± 0.40 au for C₂H₆ are in agreement with those obtained by thermochemical methods.     

Kinetics of the association of H+3 with H2 at low temperatures

The rate constant for the formation of H⁺₅ (D⁺₅) at (86 ± 3) °K by the three-body process has been determined (k₃(H) = (2.16 ± 0.10) × 10^?28 × 10^?28 cm⁶/molecule² sec and k₃(D) = (1.47 ± 0.20) × 10^?28 cm⁶/molecule² sec) in a high pressure mass spectrometer. Comparison of this result with published rate data at 300 °K indicates the reaction has an apparent activation energy of ?1.5 kcal/mole.     

稀土配合物[Pr(C3H7NO2)2(C3H4N2)(H2O)](ClO4)3的标准生成焓及热分解动力学研究

合成了高氯酸镨和咪唑(C₃H₄N₂), DL-α-丙氨酸(C₃H₇NO₂)混配配合物晶体. 经傅立叶变换红外光谱、化学分析和元素分析确定其组成为[Pr(C₃H₇NO₂)₂(C₃H₄N₂)(H₂O)](ClO₄)₃. 使用具有恒温环境的溶解-反应量热计, 以2.0 mol•L^－1 HCl为量热溶剂, 在T＝(298.150±0.001) K时测定出化学反应PrCl₃•6H₂O(s)＋2C₃H₇NO₂(s)＋C₃H₄N₂(s)＋3NaClO₄(s)＝[Pr(C₃H₇NO₂)₂(C₃H₄N₂)(H₂O)](ClO₄)₃(s)＋3NaCl(s)＋5H₂O(1)的标准摩尔反应焓为Δ_rH_m^ө＝(39.26±0.11) kJ•mol^－1. 根据盖斯定律, 计算出配合物的标准摩尔生成焓为Δ_fH_m^ө{[Pr(C₃H₇NO₂)₂(C₃H₄N₂)(H₂O)](ClO₄)₃(s), 298.150 K}＝(－2424.2±3.3) kJ•mol^－1. 采用TG-DTG技术研究了配合物在流动高纯氮气(99.99%)气氛中的非等温热分解动力学, 运用微分法(Achar-Brindley-sharp和Kissinger法)和积分法(Satava-Sestak和Coats-Redfern法)对非等温动力学数据进行分析, 求得分解反应的表观活化能E＝108.9 kJ•mol^－1, 动力学方程式为dα/dt＝2(5.90×10⁸/3)(1－α)[－ln(1－α)]^－1exp(－108.9×10³/RT).     

Fulvene—platinum complexes: x-ray crystal structure of [Pt(η2-C5H4CPh2)(PPh3)2]

Bis(cycloocta-1,5-diene)platinum reacts with 2,3,4,5-tetraphenylfulvene to afford the complex [Pt(η²-CH₂C₅Ph₄)(cod)] (cod  C₈H₁₂) in which the metal atom is coordinated to the exo-cyclic double bond of the fulvene. Related compounds [Pt(η²-CH₂C₅Ph₄L₂] (L  PPh₃, PMePh₂, PMe₂Ph, AsPh₃ or CNBu^t have also been prepared and characterised. Reaction of the complexes [Pt(C₂H₄)₂(L)] (L  P(cyclo-C₆H₁₁)₃, PPh₃ or AsPh₃) with 2,3,4,5-tetraphenylfulvene yields the compounds [Pt(C₂H₄)(η²-CH₂C₅PH₄)(L)]. NMR data for the new species are reported and discussed. 6,6-Diphenylfulvene reacts with [Pt(cod)₂] and PPh₃ ($\text{1}\text{2}$ mol ratio) to give the complex [Pt(η²-C₅H₄CPh₂)-(PPh₃)₂] in which the metal atom is bonded to carbon atoms C(2) and C(3) of the fulvene ring. This was established by an X-ray diffraction study. Crystals are monoclinic, space group P2₁/n, with Z  4 in a unit cell of dimensions a  13.761(4), b  21.653(13), c  17.395(6) Å, β,  104.46(2)°. The structure has been solved and refined to R  0.064 (R′  0.064) for 3139 independent diffracted intensifies measured at room temperature. The platinum atom is in a trigonal environment formed by the two ligated phosphorus atoms and the CC bond of the fulvene which is elongated to 1.52(3) Å. The c₅ fulvene ring is planar, and makes an angle of 108° with the coordination plane around the platinum. In this plane the metal atom is slightly asymmetrically bonded with PtC 2.15(2) and 2.24(2) Å, and PtP 2.280(6) and 2.301(6) Å.     

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.     

Vibrational characteristics and structures of allyl groups C3H+5, C3H·5 and C3−5 involved in σ, π and ionic bondings with metals

Several spectroscopic characteristics of the structure and of the nature of internal bonds in allyl groups C₃H⁺₅, C₃H^·₅ and C₃H^?₅ are compared and clearly deduced from infrared and Raman spectra of some organometallic compounds.     

The synthesis and decarbonylation of (η5-C5H5)Mo(Co)2(COCH3)E(C6H5)3, where E is arsenic or antimony

The synthesis of the title compounds by reaction of (η⁵-C₅H₅)Mo(CO)₃CH₃ with excess As(C₆H₅)₃ or Sb(C₆H₅)₃ in CH₃CN is described. Thermal decarbonylation results in the preferential ejection of As(C₆H₅)₃ or Sb(C₆H₅)₃ from the new acetyl complexes, which accounts for the failure of previous attempts to synthesise the acetyl complexes. Photolytic decarbonylations lead to new-alkyl complexes (η⁵-C₅H₅)Mo(CO)₂(CH₃)E(C₆H₅)₃. IR and NMR data for the new complexes are tabulated.     

Rotational and vibrational distributions of N2(C 3Πu) excited by state-selected Ar(3P2) and Ar(3P0) metastable atoms

The ESR method is used to study the oxidation kinetics of the CH₃, C₂H₅, n-C₄H₉, i-C₄H₉, s-C₄H₉, t-C₄H₉, n-C₆H₁₃, C₆H₁₁, C₆H₅CH₂, CH₃C₆H₄CH₂, and C₆H₅CH₂CH₂ radicals in methanol matrix at 87 K. The reaction kinetics are shown to be describable in terms of a time-dependent rate constant k(t). The contribution from the matrix relaxation to k(t) has been determined. The oxidation rate and the shape of the kinetic curve are independent of the type of the radical. Models interpreting the experimental data are discussed.