The analysis of high-resolution spectra of the ν2 and ν5 bands of CH335Cl and CH337Cl

The ν₂ and ν₅ bands of CH³₃⁵Cl and CH³₃⁷Cl between 1300 and 1600 cm⁻¹ have been analysed using a Fourier transform spectrum with 0.006 cm⁻¹ resolution. For CH³₃⁵Cl, the microwave data and 1200 lines from the IR spectrum with J⩽ 50 were fitted with an overall r.m.s. error of 0.00079 cm⁻¹ using the method of predicative observations. A similar fit for 900 lines of CH³₃⁷Cl gave an overall r.m.s. error of 0.00055 cm⁻¹, providing erroneous microwave data on the ν₅ level are omitted. Improved molecular constants are reported for both isotopic species. As expected, the values for ν₂ and ν₅ are little affected by chlorine isotopic substitution.     

Reaction of C2H2(+) (n · ν2, m · ν5) with NO2: reaction on the singlet and triplet surfaces

Integral cross sections and product recoil velocity distributions were measured for reaction of C(2)H(2)(+) with NO(2), in which the C(2)H(2)(+) reactant was prepared in its ground state, and with mode-selective excitation in the cis-bend (2ν(5)) and CC stretch (n · ν(2), n = 1, 2). Because both reactants have one unpaired electron, collisions can occur with either singlet or triplet coupling of these unpaired electrons, and the contributions are separated based on distinct recoil dynamics. For singlet coupling, reaction efficiency is near unity, with significant branching to charge transfer (NO(2)(+)), O(-) transfer (NO(+)), and O transfer (C(2)H(2)O(+)) products. For triplet coupling, reaction efficiency varies between 13% and 19%, depending on collision energy. The only significant triplet channel is NO(+) + triplet ketene, generated predominantly by O(-) transfer, with a possible contribution from dissociative charge transfer at high collision energies. NO(2)(+) formation (charge transfer) can only occur on the singlet surface, and appears to be mediated by a weakly bound complex at low energies. O transfer (C(2)H(2)O(+)) also appears to be dominated by reaction on the singlet surface, but is quite inefficient, suggesting a bottleneck limiting coupling to this product from the singlet reaction coordinate. The dominant channel is O(-) transfer, producing NO(+), with roughly equal contributions from reaction on singlet and triplet surfaces. The effects of C(2)H(2)(+) vibration are modest, but mode specific. For all three product channels (i.e., charge, O(-), and O transfer), excitation of the CC stretch fundamental (ν(2)) has little effect, 2 · ν(2) excitation results in ～50% reduction in reactivity, and excitation of the cis-bend overtone (2 · ν(5)) results in ～50% enhancement. The fact that all channels have similar mode dependence suggests that the rate-limiting step, where vibrational excitation has its effect, is early on the reaction coordinate, and branching to the individual product channels occurs later.     

Characterization of [Re2Cl3(μ-dppm)2(NCCH3)2][Cl] and [Re2Cl3(μ-dppm)2(NCC6H5)2][Cl]·2CH2Cl2 by X-ray Crystallographic and Two-Dimensional NMR Spectroscopic Techniques

The complex Re₂Cl₆(P-n-Bu₃)₂ prepared in situ reacts with CH₃CN to form a blue-green solution. Addition of the chelating phosphine bis(diphenylphosphino)methane (dppm) results in the formation of the complex [Re₂Cl₃(-dppm)₂(NCCH₃)₂][Cl] (1) upon heating. The two acetonitrile molecules adopt a trans geometry on the rhenium center with the axially coordinated chlorine. The analogous trans benzonitrile species [Re₂Cl₃(-dppm)₂(NCC₆H₅)₂][Cl]·2CH₂Cl₂ (2) is synthesized under the same reaction conditions. The coupling constants of the AABB ³¹P{¹H} NMR spectra of the compounds were elucidated from ³¹P–³¹P homonuclear J-resolved NMR experiments. Additional characterization methods include ³¹P{¹H} NMR spectroscopy, UV-vis spectroscopy, and X-ray crystallography.     

Synchrotron far infrared spectroscopy of the ground, ν(5), and ν(15) states of thiirane

The high-resolution (0.001 cm(-1)) spectrum of thiirane has been recorded at the far-infrared beamline at the Australian synchrotron between 760-400 cm(-1) and 170-10 cm(-1). Ro-vibrational transitions of the highly Coriolis coupled ν(5) (628.1 cm(-1)) and ν(15) (669.7 cm(-1)) fundamentals, as well as pure rotational far-IR transitions have been assigned, and rotational, centrifugal distortion, and Coriolis interaction parameters determined. ν(15) gains the vast majority of its intensity from an interesting Coriolis intensity stealing mechanism, which is also outlined.     

Triethylaluminum-Based Ferrocenylalanes. Synthesis and Crystal Structure of (η5−C5H5)Fe[η5−C5H4Al2(C2H5)4Cl]

Abstract

The trietheylaluminum based ferrocenylalane (η⁵?C₅H₅)Fe[η⁵?C₅H₄Al₂(C₂H₅)₄Cl] was prepared from the reaction of triethylaluminum with chloromercuriferrocene in toluene and characterized by single crystal X-ray diffraction. The compound crystallizes in the triclinic space group P 1 with unit cell dimensions a = 9.353(3) Å, b = 10.281(7) Å, c = 11.599(9) Å, α = 79.64(7)°, β = 69.41(6)°, γ = 84.33(4)°, and Z = 2 for D_c = 1.27 g cm^?3. Full-matrix least-squares refinement has led to a final R factor of 0.068 based on 1866 independent observed reflections. The two diethylaluminum units are bridged by a chlorine atom and one carbon atom of a cyclopentadienyl group, thus forming an Al-Cl-Al-C ring. The four-membered ring is planar to within 0.02 Å. The Al-Cl distances are 2.404(4) Å and 2.266(5) Å. The Al-Cl-Al angle is 78.9(1)° while the Al-C-Al angle is 91.3(4)°. No significant aluminum-iron interaction is observed (Al… Fe = 3.137(4) Å).     

Substitution and insertion reactions of (η5-C5H5)Cr(CO)3C2H5

The complex (η⁵-C₅H₅)Cr(CO)₃Cp42 H₅ has been made and its reactions with σ donor ligands L (L = (MeO)₃P and (EtO)₃P) and with SO₂ studied. The alkyl phosphites give compounds of the composition (η⁵-C₅H₅)Cr(CO)₂LC₂H₅, and sulfur dioxide gives the corresponding S-sulfinato (η⁵-C₅H₅)Cr(CO)₃SO₂C₂H₅.     

Addition of boranes to (E)-(η5-C5H5)2Zr(CH=CHPh)Cl

In this study, the addition of boranes to (E)-(η⁵-C₅H₅)₂Zr(CH=CHPh)Cl (3) has been examined in order to investigate the regioselectivity of these ‘hydroboration’ reactions. We have found that these additions proceed with remarkable selectivity to give exclusive formation of a saturated organic molecule where one carbon atom has both the boron and the zirconium fragments. These reactions do not proceed via a conventional hydroboration reaction, but instead go through an initial transmetalation step to generate (E)-(η⁵-C₅H₅)₂Zr(H)Cl (1) and the corresponding alkenyl boron intermediate, whereupon subsequent hydrozirconation of this latter species gives the geminal products. An x-ray diffraction study has been conducted on gem-(η⁵-C₅H₅)₂Zr(CH(Bpin)CH₂Ph)Cl (pin = 1, 2-O₂C₂Me₄) (2). Crystals of 2 were orthorhombic with a = 18.545(3) Å, b = 15.713(3) Å, c = 16.157(3) Å in the space group Pccn. An x-ray diffraction study has also been conducted on the trinuclear zirconium oxide species (η⁵-C₅H₅)₂ZrO₂[ZrCl(η⁵-C₅H₅)₂]₂ (4). Crystals of 4 were orthorhombic with a = 13.6000(8) Å, b = 14.2252(8) Å, c = 17.6500(10) Å in the space group P2(1)2(1)2(1).      

Structure and properties of tripyridine nitrosocomplexes of ruthenium: mer-[Ru(NO)Py3Cl(OH)]Cl·1.5H2O and mer-[Ru(NO)Py3Cl(H2O)]Cl2·2H2O·0.5HCl

The reaction of K₂[Ru(NO)Cl₅] with pyridine in aqueous ethanol at pH ～ 7–8 affords a nitrosoruthenium hydroxocomplex mer-[Ru(NO)Py₃Cl(OH)]Cl·1.5H₂O (I) (yield ～55%). Treatment of hydroxocomplex I with hydrochloric acid at room temperature gives the aqua complex mer-[Ru(NO)Py₃Cl(H₂O)]Cl₂·2H₂O·0.5HCl (II). The structures of the compounds are determined by X-ray crystallography: I, space group P2₁/n, a = 9.2292(4) Å, b = 11.7781(4) Å, c = 17.4915(7) Å, β = 90.9560(10)°, R = 4.84%; II, space group P-1, a = 7.3528(9) Å, b = 11.5793(11) Å, c = 13.6961(16) Å, α = 84.558(3)°, β = 87.668(4)°, γ = 74.146(4)°, R = 6.22%. Compounds I and II are characterized by powder XRD, ¹H and ¹³C NMR, and IR spectroscopy. The thermal decomposition of compound II in the inert atmosphere is examined by thermal analysis.     

Structural chemistry of titanium and aluminium bimetallic hydride complexes VI. Molecular structure and physico-chemical properties of (η5-C5 H5) 2Ti(μ2-H)2 Al(Cl) (μ2 -H)2Ti(η5-C5H 5)2, a catalyst-precursor for hydrogenation in the [(η5-C5H5)2TiCl]2-LiAIH4 system

The complex (Cp₂Ti)₂AlH₄Cl has been isolated from the catalytic system (Cp₂TiCl)₂-LiAlH₄, which is a precursor of the catalyst for the hydrogenation and isomerization of olefins. This complex has been studied by X-ray diffraction. The complex forms rhomboidal crystals with unit cell dimensions a = 10.414, b = 11.998, c = 16.008 Å, space group P2₁2₁2₁, Z = 4, and density ϱ_calc = 1.40 g/cm³. The Cp₂Ti moieties are linked to the Al atom via double hydrogen bridges; the Cl atom is bonded to the Al atom. Analysis of the EPR spectral data and some chemical properties of (Cp₂Ti)₂AlH₄Cl solutions has led us to suggest a mechanism for the formation of the catalytically active species upon interaction of this compound with olefins and solvating solvents.     

Crystal structure and thermal properties of [Pt(NH3)5Cl][ReCl6]Cl·H2O

The crystal structure of double complex salt [Pt(NH₃)₅Cl][ReCl₆]Cl·H₂O is determined. Crystallographic characteristics are: a = 23.9502(4) Å, b = 7.5963(1) Å, c = 8.9016(2) Å, V = 1619.49(5) ų, space group Pnma, Z = 4, d _x = 3.150 g/cm³. The packing of structural fragments is studied. It is shown that on heating the salt in a helium atmosphere up to 840 °C a mixture of two solid solutions of fcc Pt_0.90Re_0.10 and hcp Pt_0.25Re_0.75 forms.     

Molar heat capacity and thermodynamic properties of crystalline Eu(C2H5O2N)2Cl3·3H2O

A complex of europium hydrochloric acid coordinated with 2-aminoacetic acid (C₂H₅O₂N), Eu(C₂H₅O₂N)₂Cl₃·3H₂O was synthesized and characterized by IR and elements analysis. The heat capacities of the complex was measured with an automatic adiabatic calorimeter, and the thermodynamic functions [H _T ? H _298.15] and [S _T ? S _298.15] were derived in the temperature range from 80 to 340 K with temperature interval of 5 K. Thermal decomposition behavior of the complex in nitrogen atmosphere was studied by thermogravimetric (TG) analysis and differential scan calorimeter (DSC).     

Infrared investigations of the order–disorder ferroelectric phase transitions in imidazolium halogenobismuthates(III) and halogenoantimonates(III): (C3N2H5)5Bi2Cl11, (C3N2H5)5Bi2Br11 and (C3N2H5)5Sb2Br11

Infrared spectra of the powdered (C₃N₂H₅)₅Bi₂Cl₁₁, (C₃N₂H₅)₅Bi₂Br₁₁and (C₃N₂H₅)₅Sb₂Br₁₁ crystals in the region of internal vibrations of the imidazolium cations (3600 and 400 cm⁻¹) at the temperature intervals of 10–300 K, covering paraelectric–ferroelectric phase transitions, are presented and discussed in this paper. The research shows that the vibrational states of the imidazolium cations change markedly during the paraelectric–ferroelectric phase transition. The continuous nature of these transitions is well reflected in the infrared spectra, which is consistent with the previous X-ray and dielectric findings.     

ℓ-Resonance effects in the νv5, 2ν5←ν5, and ν4 + ν5←ν4 bands of C2H2 and 13C12CH2 near 13.7 μm

An extension to the previous LSCD (lower state combination difference) determination of molecular parameters involving acetylene's ν₅ fundamental and the strongest one quantum hotbands, 2ν₅←ν₅ and ν₄ + ν₅←ν₄ [J. Molec. Spectrosc. 146, 389 (1991)] has been made. A novel iterative numerical diagonalization procedure was employed to fit the vibrational states involved in the seven one quantum hotbands. This method utilizes the Hellmann—Feynman theorem to calculate first derivatives and singular value decomposition (SVD) in its least-square procedure and permits the simultaneous evaluation of the effective dipole moment responsible for the ℓ-type resonance effect upon IR intensities. A set of molecular parameters describing the rotation—vibration levels of the ground state, ν₅, ν₄, 2ν₅ and ν₄ + ν₅ for the major isotope and for ¹³C¹²CH₂ are reported based upon FT-spectrometric data taken at the McMath Solar Telescope Observatory. The improved spectroscopic parameters retrieved from this investigation will serve as a database for modelling abundances of acetylene in various astrophysical sources.     

The crystal and molecular structure of bis(η5-trimethylsilylcyclopentadienyl)titanium(IV) dichloride,Ti(η5-C5H4SiMe 3)2Cl2

Summary The crystal and molecular structure of the titanocene complex Ti(⁵-C₅H₄SiMe ₃)₂Cl₂ has been determined by X-ray diffraction studies. The compound crystallizes in the triclinic crystal system [a=6.747(8),b=12.815(2),c=12.928(4) Å and =67.16(2), =82.29(5), =74.83(4)°] in the space group with 2 formula units in the unit cell. The coordination about the titanium atom formed by the two chlorine atoms and the centroids of the cyclopentadienyl rings is that of a distorted tetrahedron. The Cl-Ti-Cl angle is 91.63° while the (centroid)-Ti-(centroid) angle is 131.02°.

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Die Kristall- und Molekülstruktur von Bis(⁵-trimethylsilylcyclopentadienyl)titan(IV)dichlorid, Ti(⁵-C₅H₄SiMe ₃)₂Cl₂

Zusammenfassung Die Kristall- und Molekülstruktur des Titanocen-Komplexes Ti(⁵-C₅H₄SiMe ₃)₂Cl₂ wurde durch eine Röntgenstrukturanalyse bestimmt. Die Verbindung kristallisiert im triklinen Kristallsystem [a=6.747(8),b=12.815(2),c=12.928(4) Å und =67.16(2), =82.29(5), =74.83(4)°] in der Raumgruppe mit 2 Formeleinheiten pro Elementarzelle. Das Titanatom ist von zwei Chloratomen und den Centroiden der Cyclopentadienylringe umgeben, wobei die Koordination des Titanatoms verzerrt tetraedrisch ist. Die Winkel Cl-Ti-Cl und (Centroid)-Ti-(Centroid) betragen 91.63° bzw. 131.02°.

     

Comparison and assessment of procedures for calculating the R(12) line strength of the ν1 + 2 ν2 + ν3 band of CO2

Recently, results for the CO(2) R(12) line strength parameter have been reported, which differ significantly and are inconsistent with respect to quoted uncertainties. We investigate to what extent this inconsistency might be caused by the chosen data analysis methods. To this end, we assess and compare a parametric fitting procedure and a non-parametric approach. We apply the methods to simulated and measured line spectra, and we specify the conditions required for the safe application of the two procedures. For our present data, the corresponding conditions are satisfied for both methods, and consistent results are obtained. However, the simulations reveal that the fitting procedure can show shortcomings when the uncertainty in the wavenumber is large.     

Study of the ν1, ν1 + ν3 and ν2 + ν3 infrared bands of ONCl

A type (ΔK_a = 0) rovibrational lines of the near-prolate asymmetric top ¹⁶O¹⁴N³⁵Cl have been assigned on high resolution Fourier transform spectra: 820 lines of the ν₁ band, centered around 1800 cm⁻¹, 435 lines of the ν₁ + ν₃ band, centered around 2131 cm⁻¹, and 257 lines of the ν₂ + ν₃ band, centered around 925 cm⁻¹. Least-squares calculations have been carried out over these lines, using the A reduced Watson's hamiltonian in I^r representation; r.m.s. standard deviations of 0.0016 cm⁻¹, 0.0016 cm⁻¹ and 0.006 cm⁻¹ have been respectively obtained, making it possible to measure molecular constants of the (001), (101) and (011) vibrational levels of ¹⁶O¹⁴N³⁵Cl.     

New [Ti(η5-C5H5)Cl2(OR)] complexes. Crystal and molecular structure of η5-Cyclopentadienyl(cyclohexoxy)titanium(IV) dichloride

Summary A series of new compounds with molecular formula [Ti(⁵-C₅H₅)Cl₂(OR)] (R=C₆H₁₁ (cyclohexyl,1), CH₂CH(CH₃)₂ (2), CH(C₂H₅)₂ (3), and CH₂C₆H₅ (4)) has been obtained by the reaction of [Ti(⁵-C₅H₅)Cl₃] with the appropriate alcohol. All complexes were characterized by elemental analysis and by IR and¹H NMR spectroscopy. The structure of1 was determined by X-ray diffraction studies; crystal data: triclinic,a=11.334(2),b=13.590(2),c=12.237(2) Å, =113.501(5), =118.182(5), =101.993(6),V=1328.2(4) ų,T=298K, space P1,Z=4, two crystallographically independent molecules in the unit cell. FinalR andR _w values are 0.0583 and 0.0632, respectively. Compound1 exhibits surprisingly short Ti-Cl and Ti-O distances, suggesting strong donation by the chloride and in particular by the alkoxide ligand. The Ti-O-C angle is unusually large.

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Neue [Ti(⁵-C₅H₅)Cl₂(OR)]-Komplexe. Kristall- und Molekülstruktur von ⁵-Cyclopentadienyl(cyclohexoxy)titan(IV) Dichlorid

Zusammenfassung Durch Umsetzung von [Ti(⁵-C₅H₅)Cl₃] mit dem geeigneten Alkohol wurde eine Reihe von neuen Verbindungen der Formel [Ti(⁵-C₅H₅)(OR)] (R=C₆H₁₁ (cyclohexyl,1), CH₂CH(CH₃)₂ (2), CH(C₂H₅)₂ (3) und CH₂C₆H₅ (4)) erhalten. Alle Komplexe wurden elementaranalytisch sowie IR- und¹H-NMR-spektroskopisch charakterisiert. Die Struktur von1 wurde röntgenographisch bestimmt; Kristalldaten: triklin,a=11.334(2),b=13.590(2),c=12.237(2) Å, =113.501(5), =118.182(5), =101.993(6),V=1328.2(4) ų,T=298K, Raumgruppe P1,Z=4, zwei kristallographisch unabhängige Moleküle in der Elementarzelle; abschließendeR-Werte:R=0.0583 undR _w=0.0632. Verbindung1 zeigt überraschend kurze Ti-Cl- und Ti-O-Abstände; dies deutet auf eine starke -Elektronendonorwirkung des Chlorid- und vor allem des Alkoxidliganden hin. Der Ti-O-C-Bindungswinkel ist ungewöhnlich groß.

     

Detection of σ-alkane complexes of manganese by NMR and IR spectroscopy in solution: (η5-C5H5)Mn(CO)2(ethane) and (η5-C5H5)Mn(CO)2(isopentane)

Irradiation of CpMn(CO)₃ in liquid ethane at 135 K at 355 nm yields a photoproduct that exhibits ν(CO) bands in the IR spectrum shifted to low wavenumber with respect to CpMn(CO)₃ that are indicative of a Mn(i) dicarbonyl. Parallel experiments employing in situ irradiation within an NMR probe (133 K, 355 nm photolysis) reveal the ¹H NMR signals of this product and confirm its formulation as the σ-ethane complex CpMn(CO)₂(η²-C1–H-ethane). The resonance of its coordinated C–H group is observed at δ –5.84 and decays with lifetime of ca. 360 s. Analogous photolysis experiments in isopentane solution with IR detection produce CpMn(CO)₂(η²-C–H-isopentane) with similar IR bands to those of CpMn(CO)₂(η²-C–H-ethane). ¹H NMR spectra of the same species were obtained by irradiation of CpMn(CO)₃ in a 60 : 40 mixture of propane and isopentane; three isomers of CpMn(CO)₂(η²-C–H-isopentane) were detected with coordination of manganese at the two inequivalent methyl positions and at the methylene group, respectively. The lifetimes of these isomers are ca. 380 ± 20 s at 135 K and do not vary significantly from each other. These σ-complexes of manganese are far more reactive than those of related CpRe(CO)₂(alkane) complexes which are stable in solution at 170–180 K. The room temperature lifetimes of CpMn(CO)₂(η²-C–H-ethane) and CpMn(CO)₂(η²-C–H-isopentane), as determined by TRIR spectroscopy, are 2.0 ± 0.1 and 28 ± 1 μs, respectively.