Interaction energy and the shift in OH stretch frequency on hydrogen bonding for the H2O → H2O,CH3OH → H2O,and H2O → CH3OH dimers

The ability to use calculated OH frequencies to assign experimentally observed peaks in hydrogen bonded systems hinges on the accuracy of the calculation. Here we test the ability of several commonly employed model chemistries—HF, MP2, and several density functionals paired with the 6‐31+G(d) and 6‐311++G(d,p) basis sets—to calculate the interaction energy (D_e) and shift in OH stretch fundamental frequency on dimerization (δ(ν)) for the H₂O → H₂O, CH₃OH → H₂O, and H₂O → CH₃OH dimers (where for X → Y, X is the hydrogen bond donor and Y the acceptor). We quantify the error in D_e and δ(ν) by comparison to experiment and high level calculation and, using a simple model, evaluate how error in D_e propagates to δ(ν). We find that B3LYP and MPWB1K perform best of the density functional methods studied, that their accuracy in calculating δ(ν) is ≈ 30–50 cm^?1 and that correcting for error in D_e does little to heighten agreement between the calculated and experimental δ(ν). Accuracy of calculated δ(ν) is also shown to vary as a function of hydrogen bond donor: while the PBE and TPSS functionals perform best in the calculation of δ(ν) for the CH₃OH → H₂O dimer their performance is relatively poor in describing H₂O → H₂O and H₂O → CH₃OH. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010     

Ab initio molecular orbital study on structures and energetics of CH3O−(H2O)n and CH3S−(H2O)n in gas phase

The purpose of this article was to calculate the structures and energetics of CH₃O⁻(H₂O)_n and CH₃S⁻(H₂O)_n in the gas phase; the maximum number of water molecules that can directly interact with the O of CH₃O⁻; and when n is larger, we asked how the CH₃O⁻ and CH₃S⁻ moiety of CH₃O⁻(H₂O)_n and CH₃S⁻(H₂O)_n changes and how we can reproduce experimental ΔH ⁰_{n−1, n}. Using the ab initio closed-shell self-consistent field method with the energy gradient technique, we carried out full geometry optimizations with the MP2/aug-cc-pVDZ for CH₃O⁻(H₂O)_n (n=0, 1, 2, 3) and the MP2/6–31+G(d,p) (for n=5, 6). The structures of CH₃S⁻(H₂O)_n (n=0, 1, 2, 3) were fully optimized using MP2/6–31++G(2d,2p). It is predicted that the CH₃O⁻(H₂O)₆ does not exist. We also performed vibrational analysis for all clusters [except CH₃O⁻(H₂O)₆] at the optimized structures to confirm that all vibrational frequencies are real. Those clusters have all real vibrational frequencies and correspond to equilibrium structures. The results show that the above maximum number of water molecules for CH₃O⁻ is five in the gas phase. For CH₃O⁻(H₂O)_n, when n becomes larger, the C—O bond length becomes longer, the C—H bond lengths become smaller, the HCO bond angles become smaller, the charge on the hydrogen of CH₃ becomes more positive, and these values of CH₃O⁻(H₂O)_n approach the corresponding values of CH₃OH with the n increment. The C—O bond length of CH₃O⁻(H₂O)₃ is longer than the C—O bond length of CH₃O⁻ in the gas phase by 0.044 Å at the MP2/aug-cc-pVDZ level of theory. The structure of the CH₃S⁻ moiety in CH₃S⁻(H₂O)_n does not change with the n increment. ©1999 John Wiley & Sons, Inc. J Comput Chem 20: 1138–1144, 1999     

Preparation of New Derivatives of the closo-Dodecaborate Anion [B12H10(OC(O)CH3){OC(O)(CH2)3CH3}]2–, [B12H10(OH){OC(O)(CH2)3CH3}]2–, [B12H10(SCN){OC(O)(CH2)3CH3}]2–, and [B12H10(I){OC(O)(CH2)3CH3}]2–

Nucleophilic substitution reactions of the monosubstituted anions [B₁₂H₁₁X]^2–, where X = OC(O)CH₃, OH, SCN, and I, with pentanoic acid were studied. The obtained compounds were shown to contain the [B₁₂H₁₀X{OC(O)(CH₂)₃CH₃}]^2– anions.     

Atmospheric chemistry of n‐CH3(CH2)xCN (x = 0–3): Kinetics and mechanisms

Smog chamber/Fourier transform infrared (FTIR) techniques were used to measure the kinetics of the reaction of n‐CH₃(CH₂)_xCN (x = 0–3) with Cl atoms and OH radicals: k(CH₃CN + Cl) = (1.04 ± 0.25) × 10⁻¹⁴, k(CH₃CH₂CN + Cl) = (9.20 ± 3.95) × 10⁻¹³, k(CH₃(CH₂)₂CN + Cl) = (2.03 ± 0.23) × 10⁻¹¹, k(CH₃(CH₂)₃CN + Cl) = (6.70 ± 0.67) × 10⁻¹¹, k(CH₃CN + OH) = (4.07 ± 1.21) × 10⁻¹⁴, k(CH₃CH₂CN + OH) = (1.24 ± 0.27) × 10⁻¹³, k(CH₃(CH₂)₂CN + OH) = (4.63 ± 0.99) × 10⁻¹³, and k(CH₃(CH₂)₃CN + OH) = (1.58 ± 0.38) × 10⁻¹² cm³ molecule⁻¹ s⁻¹ at a total pressure of 700 Torr of air or N₂ diluents at 296 ± 2 K. The atmospheric oxidation of alkyl nitriles proceeds through hydrogen abstraction leading to several carbonyl containing primary oxidation products. HC(O)CN, NCC(O)OONO₂, ClC(O)OONO₂, and HCN were identified as the main oxidation products from CH₃CN, whereas CH₃CH₂CN gives the products HC(O)CN, CH₃C(O)CN, NCC(O)OONO₂, and HCN. The oxidation of n‐CH₃(CH₂)_xCN (x = 2–3) leads to a range of oxygenated primary products. Based on the measured OH radical rate constants, the atmospheric lifetimes of n‐CH₃(CH₂)_xCN (x = 0–3) were estimated to be 284, 93, 25, and 7 days for x = 0,1, 2, and 3, respectively.     

Enzyme-catalysed Transformations of Compounds Containing the –CH2-AsO3H2 Group

Enzymes that act on substrates R–O–PO₃H₂ often work on substrate analogues R–O–AsO₃H₂; such substrates are unstable, since esters of H₃AsO₄ hydrolyse easily. They also form easily, so that an enzyme that acts on R–O–PO₃H₂ often acts on a mixture of R–OH and arsenate via an ester that forms at the active site. Similarly coenzyme analogues may be formed; for example, a stable and active aspartate aminotransferase forms from the apoenzyme with free pyridoxal and arsenate. Enzymes that convert R–O–PO₃H₂ into a diester often act on R–CH₂–AsO₃H₂, a stable substrate analogue; then the product is unstable and hydrolyses to re-form the analogue, giving a futile cycle. For example, RNA polymerase acquires exonuclease activity in the presence of H₂O₃P–CH₂–AsO₃H₂; adenylate kinase acquires ATPase activity in the presence of the arsonomethyl analogue of AMP. A recent observation is that HO–CH₂–CHOH–CH₂–CH₂–AsO₃H₂ is a good substrate for glycerol-3-phosphate dehydrogenase. The product is unstable and eliminates arsenite, sharing this ability with other 3-oxoalkylarsonates. Thus this enzyme–catalysed oxidation is a lethal synthesis, in view of the toxicity of arsenite. Another unusual biochemical reaction of an arsonic acid is seen in the ability of a bacterium to use arsonoacetate as its sole source of carbon and energy. In contrast with the elimination of arsenite by 3-oxoalylarsonic acids, 3-oxoalkylphosphonic acids, R–CO–CH₂–CH₂–PO₃H₂, are stable. 2-Oxoalkylphosphonic acids, R–CO–CH₂–PO₃H₂, however, are moderately unstable to hydrolysis, yielding phosphate and R–CO–CH₃. 2-Oxoalkylarsonic acids, R–CO–CH₂–AsO₃H₂, decompose in the same way, but much more readily, yielding arsenate. © 1997 by John Wiley & Sons, Ltd.     

Analysis of Nascent Rotational Energy Distributions and Reaction Mechanisms of the Gas‐Phase Radical–Radical Reaction O(3P)+(CH3)2CH→C3H6+OH

This paper reports on the gas‐phase radical–radical dynamics of the reaction of ground‐state atomic oxygen [O(³P), from the photodissociation of NO₂] with secondary isopropyl radicals [(CH₃)₂CH, from the supersonic flash pyrolysis of isopropyl bromide]. The major reaction channel, O(³P)+(CH₃)₂CH→C₃H₆ (propene)+OH, is examined by high‐resolution laser‐induced fluorescence spectroscopy in crossed‐beam configuration. Population analysis shows bimodal nascent rotational distributions of OH (X²Π) products with low‐ and high‐N′′ components in a ratio of 1.25:1. No significant spin–orbit or Λ‐doublet propensities are exhibited in the ground vibrational state. Ab initio computations at the CBS‐QB3 theory level and comparison with prior theory show that the statistical method is not suitable for describing the main reaction channel at the molecular level. Two competing mechanisms are predicted to exist on the lowest doublet potential‐energy surface: direct abstraction, giving the dominant low‐N′′ components, and formation of short‐lived addition complexes that result in hot rotational distributions, giving the high‐N′′ components. The observed competing mechanisms contrast with previous bulk kinetic experiments conducted in a fast‐flow system with photoionization mass spectrometry, which suggested a single abstraction pathway. In addition, comparison of the reactions of O(³P) with primary and tertiary hydrocarbon radicals allows molecular‐level discussion of the reactivity and mechanism of the title reaction.     

Three new isomers of [C2H6O]+˙: The radical cations [CH3O(H)CH2]+˙, [CH3CHOH2]+˙ and a low-energy isomer of unassigned structure

Three new [C₂H₆O]⁺˙ ions have been generated in the gas phase by appropriate dissociative ionizations and characterized by means of their metastable and collisionally induced fragmentations. The heats of formation, ΔH_f⁰, of the two ions which were assigned the structures [CH₃O(H)CH₂]⁺˙ and [CH₃CHOH₂]⁺˙ could not be measured. The third isomer, to which the structure \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 2} = \mathop {\rm C}\limits^{\rm .} {\rm H} \cdot \cdot \cdot \mathop {\rm H}\limits^ + \cdot \cdot \cdot {\rm OH}_{\rm 2} $\end{document} is tentatively assigned, was measured to have ΔH_f⁰ = 732±5 kJ mol^?1, making it the [C₂H₆O]⁺˙ isomer of lowest experimental heat of formation. It was found that the exothermic ion–radical recombinations [CH₂OH]⁺+CH₃˙→[CH₃O(H)CH₂]⁺˙ and \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 3} \mathop {\rm C}\limits^{\rm + } {\rm HOH + H}^{\rm .} $\end{document}→[CH₃CHOH₂]⁺˙ have large energy barriers, 1.4 and ?0.9 eV, respectively, whereas the recombinations yielding [CH₃CH₂OH]⁺˙ have little or none.     

铋(Ⅲ)配合物Bi(1,10-phen)[S2CN(CH3)2]2(NO3),

Three bismuth（Ⅲ） complexes Bi（1,10-phen）[S2CN（CH3）2]2（NO3） （1）, {Bi（S2COCH3）[S2CNC6Hs（CH3）]2}2 （2） and [Bi（S2CNBu2）2（CH3OH）（NO3）]∞ （3） were synthesized and characterized by elemental analysis and IR spectra. Their crystal structures were determined by X-ray single crystal diffraction analysis. Studies show that complex 1 has a monomeric structure with the central bismuth atom eight-coordinated in a capped distorted pentagonal bipyramidal geometry. The complex 2 takes centrosymmetric dimeric structure and the bismuth atoms are seven-coordinated in distorted pentagonal bipyramidal geometry.In complex 3, the bismuth atoms are seven-coordinated in distorted pentagonal bipyramidal geometry by bridging nitrate O atoms and the resulting structure is onedimensional infinite chain polymer.     

A Computational Study of the Kinetics and Mechanism for the C2H3 + CH3OH Reaction

The mechanism for the C₂H₃ + CH₃OH reaction has been investigated by the Gaussian‐4 (G4) method based on the geometric parameters of the stationary points optimized at the B3LYP/6–31G(2df, p) level of theory. Four transition states have been identified for the production of C₂H₄ + CH₃O (TSR/P1), C₂H₄ + CH₂OH (TSR/P2), C₂H₃OH + CH₃ (TSR/P3), and C₂H₃OCH₃ + H (TSR/P4) with the corresponding barriers 8.48, 9.25, 37.62, and 34.95 kcal/mol at the G4 level of theory, respectively. The rate constants and branching ratios for the two lower energy H‐abstraction reactions were calculated using canonical variational transition state theory with the Eckart tunneling correction at the temperature range 300–2500 K. The predicted rate constants have been compared with existing literature data, and the uncertainty has been discussed. The branching ratio calculation suggests that the channel producing CH₃O is dominant up to about 1070 K, above which the channel producing CH₂OH becomes very competitive.     

Kinetics of the reactions of CH3O with Cl and CIO

The kinetics of the reactions CH₃O + Cl → H₂CO + HCl (1) and CH₃O + ClO → H₂CO + HOCl (2) have been studied using the discharge-flow techniques. CH₃O was monitored by laser-induced fluorescence, whereas mass spectrometry was used for the detection or titration of other species. The rate constants obtained at 298 K are: k₁ = (1.9 ± 0.4) × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹ and k₂ = (2.3 ± 0.3) × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹. These data are useful to interpret the results of the studies of the reactions of CH₃O₂ with Cl and ClO which, at least partly, produce CH₃O radicals. © 1996 John Wiley & Sons, Inc.     

Master Equation Modeling of the Unimolecular Decompositions of α‐Hydroxyethyl (CH3CHOH) and Ethoxy (CH3CH2O) Radicals

The unimolecular decomposition of two radical isomers of C₂H₅O (CH₃CH₂O/ethoxy, CH₃CHOH/α‐hydroxyethyl) are investigated by means of Rice–Ramsperger–Kassel–Marcus/master equation simulations in helium and nitrogen bath gases on an accurate one‐dimensional potential energy surface. For ethoxy, simulations are carried out between temperatures of 406 and 1200 K and pressures of 0.001 and 100 atm. For CH₃CHOH, simulations are carried out between temperatures of 800 and 1500 K and pressures of 0.001 and 100 atm. Results are compared with available experimental data, with good agreement. The dominant product of α‐hydroxyethyl decomposition is CH₃CHO + H, with C₂H₃OH + H and CH₃ + CH₂O, being minor channels. Rate coefficients are strongly dependent on temperature and pressure and are recommended with attendant uncertainty factor estimates. The relative roles of vinyl alcohol and acetaldehyde in the context of combustion chemistry are also discussed.     

Study on the equilibrium in the M(CH3COO)2 ? CH3OH ? H2O system (M  Mg2+, Ca2+, Ba2+) at 25°C

The complex formation and dehydration processes in the system M(CH₃COO)₂? CH₃OH? H₂O have been studied by the methods of the physico-chemical analysis at 25°C; (M = Mg²⁺, Ca²⁺ and Ba²⁺). In the Mg(CH₃COO)₂? CH₃OH? H₂O system. methanol was found to behave as a solvent in which complex formation reactions take place, including also methanolation of Mg²⁺. The fields of equilibrium existence of two new compounds have been found: Mg(CH₃COO)₂ · 3H₂O · CH₃OH and Mg(CH₃COO)₂ · 1,5 CH₃OH. In the systems M(CH₃COO)₂? CH₃OH? H₂O (M = Ca²⁺, Ba²⁺), methanol was found to react as a dehydrating reagent.     

Kinetic study of the reaction of OH with CH3I revisited

A flash photolysis resonance fluorescence technique has been employed to investigate the kinetics and mechanism of the reaction of OH(X²Π) radicals with CH₃I over the temperature and pressure ranges 295–390 K and 82–303 Torr of He, respectively. The experiments involved time‐resolved RF detection of the OH (A²Σ⁺ → X²Π transition at λ = 308 nm) following FP of H₂O/CH₃I/He mixtures. The OH(X²Π) radicals were produced by FP of H₂O in the vacuum‐UV at wavelengths λ > 115 nm using a commercial Perkin‐Elmer Xe flash lamp. Decays of OH in the presence of CH₃I are observed to be exponential, and the decay rates are found to be linearly dependent on the CH₃I concentration. The measured rate coefficients for the reaction of OH with CH₃I are described by the Arrhenius expression k_OH+CH3I = (4.1 ± 2.2) × 10^?12 exp [(?1240 ± 200)K/T] cm³ molecule^?1s^?1. The implications of the reported kinetic results for understanding the CH₃I chemistry of both atmospheric and nuclear industry interests are discussed. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 547–556, 2011     

Formation and hydrolysis of gas‐phase [UO2(R)]+: R═CH3, CH2CH3, CH═CH2, and C6H5

The goals of the present study were (a) to create positively charged organo‐uranyl complexes with general formula [UO₂(R)]⁺ (eg, R═CH₃ and CH₂CH₃) by decarboxylation of [UO₂(O₂C─R)]⁺ precursors and (b) to identify the pathways by which the complexes, if formed, dissociate by collisional activation or otherwise react when exposed to gas‐phase H₂O. Collision‐induced dissociation (CID) of both [UO₂(O₂C─CH₃)]⁺ and [UO₂(O₂C─CH₂CH₃)]⁺ causes H⁺ transfer and elimination of a ketene to leave [UO₂(OH)]⁺. However, CID of the alkoxides [UO₂(OCH₂CH₃)]⁺ and [UO₂(OCH₂CH₂CH₃)]⁺ produced [UO₂(CH₃)]⁺ and [UO₂(CH₂CH₃)]⁺, respectively. Isolation of [UO₂(CH₃)]⁺ and [UO₂(CH₂CH₃)]⁺ for reaction with H₂O caused formation of [UO₂(H₂O)]⁺ by elimination of ·CH₃ and ·CH₂CH₃: Hydrolysis was not observed. CID of the acrylate and benzoate versions of the complexes, [UO₂(O₂C─CH═CH₂)]⁺ and [UO₂(O₂C─C₆H₅)]⁺, caused decarboxylation to leave [UO₂(CH═CH₂)]⁺ and [UO₂(C₆H₅)]⁺, respectively. These organometallic species do react with H₂O to produce [UO₂(OH)]⁺, and loss of the respective radicals to leave [UO₂(H₂O)]⁺ was not detected. Density functional theory calculations suggest that formation of [UO₂(OH)]⁺, rather than the hydrated U^VO₂⁺, cation is energetically favored regardless of the precursor ion. However, for the [UO₂(CH₃)]⁺ and [UO₂(CH₂CH₃)]⁺ precursors, the transition state energy for proton transfer to generate [UO₂(OH)]⁺ and the associated neutral alkanes is higher than the path involving direct elimination of the organic neutral to form [UO₂(H₂O)]⁺. The situation is reversed for the [UO₂(CH═CH₂)]⁺ and [UO₂(C₆H₅)]⁺ precursors: The transition state for proton transfer is lower than the energy required for creation of [UO₂(H₂O)]⁺ by elimination of CH═CH₂ or C₆H₅ radical.     

Syntheses and structural study of trinuclear iron acetates [Fe3O(CH3COO)6(H2O)3]Cl· 6H2O and [Fe3O(CH3COO)6(H2O)3] [FeCl4]· 2CH3COOH

The structure of two trinuclear iron acetates [Fe₃O(CH₃COO)₆(H₂O)₃]Cl· 6H₂O (I) and [Fe₃O(CH₃COO)₆(H_2O)₃][FeCl₄] · 2CH₃COOH (II) was determined by X-ray diffraction analysis. Crystals I and II are ionic and belong to the orthorhombic system with parameters a = 13.704(3), b = 23.332(5), c = 9.167(2) Å, R = 0.0355, space goup P2₁2₁2 for I and a = 10.145(4), b = 15.323(6), c = 22.999(8) Å, R = 0.0752, space group Pbc2₁ for II. The complex cation [Fe₃O(CH₃COO)₆(H₂O)₃]⁺ has a μ₃-O-bridged structure typical for trinuclear iron (III) compounds. As shown by Mössbauer spectroscopy, the iron(III) ions are in the high-spin state. In trinuclear cations, antiferromagnetic exchange interaction takes place between the Fe(III) ions with the exchange parameter J = -26.69 cm^?1 for II (Heisenberg-Dirac-Van Vleck model for D_3h, symmetry).     

Synthese und Kristallstruktur von Praseodympropionat-trihydrat,Pr(CH3CH2COO)3(H2O)3

Synthesis and Crystal Structure of Praseodymium Propionate Trihydrate, Pr(CH₃CH₂COO)₃(H₂O)₃ Single crystals of Pr(CH₃CH₂COO)₃(H₂O)₃ were obtained by dissolving freshly prepared praseodymium hydroxide in diluted propionic acid. The crystal structure (monoclinic, P2₁/c, Z = 4, a = 1034.2(2) pm, b = 1521.2(3) pm, c = 2086.3(7) pm, β = 102.87(2)°, R1 = 0.0864, wR2 = 0.1196) consists of one-dimensional infinite chains parallel [010]. Pr1 and Pr2 are coordinated by four tridentate-bridging propionate groups. Additionally, Pr1 is coordinated by three “coordination water” molecules, Pr2 by two bidentate propionate groups. There are, in addition, three “crystal water” molecules so that praseodymium propionate trihydrate should be formulated as [(H₂O)₃Pr1(CH₃CH₂COO)₄Pr2(CH₃CH₂COO)₂] (H₂O)₃.     

Die Konstitution des Tetramethylammoniumsilicats der Zusammensetzung 1,0 N(CH3)4OH 1,0 SiO2 · 8,0–8,3 H2O

By means of paperchromatographic, kinetic and X-ray methods it is shown that the tetramethylammonium silicate of the composition 1 N(CH₃)₄OH · 1 SiO₂ · ～8 H₂O has not – as hitherto supposed – the constitution of a poly- or phyllosilicate, but that of a tetra-anhydrido-bis-cyclotetrasilicate (double-fourringsilicate), [(CH₃)₄N]₈[Si₈O₂₀] · ～69 H₂O. Its trimethylsilylation by means of hexamethyldisiloxane gives the corresponding, crystalline trimethylsilyl ester [(CH₃)₃Si]₈[Si₈O₂₀], which has been characterised by mass spectroscopy.     

UV absorption spectra of HO2, CH3O2, C2H5O2, and CH3C(O)CH2O2 radicals and mechanism of the reactions of F and Cl atoms with CH3C(O)CH3

Pulse radiolysis techniques were used to measure the gas phase UV absorption spectra of the title peroxy radicals over the range 215–340 nm. By scaling to σ(CH₃O₂)_{240 nm} = (4.24 ± 0.27) × 10^?18, the following absorption cross sections were determined: σ(HO₂)_{240 nm} = 1.29 ± 0.16, σ(C₂H₅O₂)_{240 nm} = 4.71 ± 0.45, σ(CH₃C(O)CH₂O₂)_{240 nm} = 2.03 ± 0.22, σ(CH₃C(O)CH₂O₂)_{230 nm} = 2.94 ± 0.29, and σ(CH₃C(O)CH₂O₂)_{310 nm} = 1.31 ± 0.15 (base e, units of 10^?18 cm² molecule^?1). To support the UV measurements, FTIR‐smog chamber techniques were employed to investigate the reaction of F and Cl atoms with acetone. The F atom reaction proceeds via two channels: the major channel (92% ± 3%) gives CH₃C(O)CH₂ radicals and HF, while the minor channel (8% ± 1%) gives CH₃ radicals and CH₃C(O)F. The majority (>97%) of the Cl atom reaction proceeds via H atom abstraction to give CH₃C(O)CH₂ radicals. The results are discussed with respect to the literature data concerning the UV absorption spectra of CH₃C(O)CH₂O₂ and other peroxy radicals. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 283–291, 2002     

Kristallstruktur und Schwingungsspektrum von (H2NPPh3)2[SnCl6]·2CH3CN

Crystal Structure and Vibrational Spectrum of (H₂NPPh₃)₂[SnCl₆]·2CH₃CN Single crystals of (H₂NPPh₃)₂[SnCl₆]·2CH₃CN ( 1 ) were obtained by oxidative addition of tin(II) chloride with N‐chloro‐triphenylphosphanimine in acetonitrile in the presence of water. 1 is characterized by IR and Raman spectroscopy as well as by a single crystal structure determination: Space group , Z = 2, lattice dimensions at 193 K: a = 1029.6(1), b = 1441.0(2), c = 1446.1(2) pm, α = 90.91(1)°, β = 92.21(1)°, γ = 92.98(1)°, R₁ = 0.0332. 1 forms an ionic structure with two different site positions of the [SnCl₆]^2? ions. One of them is surrounded by four N‐hydrogen atoms of four (H₂NPPh₃)⁺ ions, four CH₃CN molecules form N–H···N≡C–CH₃ contacts with the other four N‐hydrogen atoms of the cations. Thus, 1 can be written as [(H₂NPPh₃)₄(CH₃CN)₄(SnCl₆)]²⁺[SnCl₆]^2?.     

[Be3(μ3‐O)3(MeCN)6{Be(MeCN)3}3](I)6 – ein Berylliumkomplex mit Cyclo‐(Be3O3)‐Kern und sein Hydrolyseprodukt [Be(H2O)4](I)2·2MeCN

Single crystals of [Be₃(μ₃‐O)₃(MeCN)₆{Be(MeCN)₃}₃](I)₆·4CH₃CN ( 1 ·4CH₃CN) were obtained in low yield by the reaction of beryllium powder with iodine in acetonitrile suspension, which probably result from traces of beryllium oxide containing the applied beryllium metal. The compound 1 ·4CH₃CN forms moisture sensitive, colourless crystal needles, which were characterized by IR spectroscopy and X‐ray diffraction (Space group Pnma, Z = 4, lattice dimensions at 100(2) K: a = 2317.4(1), b = 2491.4(1), c = 1190.6(1) pm, R₁ = 0.0315). The hexaiodide complex cation 1 ⁶⁺consists of a cyclo‐Be₃O₃ core with slightly distorted chair conformation, stabilized by coordination of two acetonitrile ligands at each of the beryllium atoms and by a {Be(CH₃CN)₃}²⁺ cation at each of the oxygen atoms. This unique coordination behaviour results in coplanar OBe₃ units with short Be–O distances of 155.0 pm and 153.6 pm on average of bond lengths within the cyclo‐Be₃O₃ unit and of the peripheric BeO bonds, respectively. Exposure of compound 1 ·4CH₃CN to moist air leads to small orange crystal plates of [Be(H₂O)₄]I₂·2CH₃CN ( 3 ·2CH₃CN). According to the crystal structure determination (Space group C2/c, Z = 4, lattice dimensions at 100(2) K: a = 1220.7(1), b = 735.0(1), c = 1608.5(1) pm, β = 97.97(1)°, R₁ = 0.0394), all hydrogen atoms of the dication [Be(H₂O)₄]²⁺ are involved to form O–H ··· N and O–H ··· I hydrogen bonds with the acetonitrile molecules and the iodide ions, respectively. Quantum chemical calculations (B3LYP/6‐311+G**) at the model [Be₃(μ₃‐O)₃(HCN)₆{Be(HCN)₃}₃]⁶⁺ show that chair and boat conformation are stable and that the distorted chair conformation is stabilized by packing effects.