Theoretical determination of the X 2Σ+ and A 2Π potentials of CsO using relativistic effective core potentials

Theoretical potential energy curves are computed for the X ²Σ⁺ and A ²Π states of CsO using a relativistic effective core potential and a large valence Gaussian basis set. Seventeen electrons are correlated by a CI (SD ) calculation from each HF reference. We find the X ²Σ⁺ state lower by 497 and 726 cm^?1 at the HF and CI(SD) levels. Our calculated ω_e of 312 cm^?1 for the X ²Σ⁺ state agrees well with experimental values deduced from studies in matrices.     

Tricarbonyl(η5‐formylcyclopentadienyl)manganese(I) and tricarbonyl(η5‐formylcyclopentadienyl)rhenium(I) containing short π(CO)...π(CO) and π(CO)...π interactions

The structures of tricarbonyl(formylcyclopentadienyl)manganese(I), [Mn(C₆H₅O)(CO)₃], (I), and tricarbonyl(formylcyclopentadienyl)rhenium(I), [Re(C₆H₅O)(CO)₃], (II), were determined at 100 K. Compounds (I) and (II) both possess a carbonyl group in a trans position relative to the substituted C atom of the cyclopentadienyl ring, while the other two carbonyl groups are in almost eclipsed positions relative to their attached C atoms. Analysis of the intermolecular contacts reveals that the molecules in both compounds form stacks due to short attractive π(CO)...π(CO) and π(CO)...π interactions, along the crystallographic c axis for (I) and along the [201] direction for (II). Symmetry‐related stacks are bound to each other by weak intermolecular C—H...O hydrogen bonds, leading to the formation of the three‐dimensional network.     

Dehydrogenation of adenine induced by slow (<3 eV) electrons

Low energy (<3 eV) electrons impact to gas phase Adenine generates the dehydrogenated Adenine negative fragments, (A–H)⁻, and an H-atom neutral radical counterpart. Within the energy range of 0.7–2.8 eV, production of (A–H)⁻ arises from Dissociative Electron Attachment (DEA). In addition, a sharp peak is observed at near 0 eV. This peak is identified to arise from dissociative electron transfer reaction of SF₆⁻ (from the calibration gas) with Adenine.     

Theoretical analysis of the O + CS(0) → CO(υ′)+ S reaction by the two half-collisions model

A theoretical analysis of the O + CS → CO + S reaction is presented. It is shown that the experimental CO vibrational distribution can be explained by a collinear O + CS reaction which proceeds via the lowest triplet OCS electronic state.     

Koordinativ ungesättigte Dirutheniumkomplexe: Synthese und Kristallstrukturen von [Ru2(CO)3L(μ‐η1 : η2‐C≡CPh)(μ‐PtBu2)(μ‐Ph2PCH2PPh2)] (L = CO,PnBu3)

Coordinatively Unsaturated Diruthenium Complexes: Synthesis and X‐ray Crystal Structures of [Ru₂(CO)₃L(μ‐η¹ : η²‐C≡CPh)(μ‐P^tBu₂)(μ‐Ph₂PCH₂PPh₂)] (L = CO, PⁿBu₃) [Ru₂(CO)₄(μ‐H)(μ‐P^tBu₂)(μ‐dppm)] ( 1 ) reacts with several phosphines (L) in refluxing toluene under substitution of one carbonyl ligand and yields the compounds [Ru₂(CO)₃L(μ‐H)(μ‐P^tBu₂)(μ‐dppm)] (L = PⁿBu₃, 2 a ; L = PCy₂H, 2 b ; L = dppm‐P, 2 c ; dppm = Ph₂PCH₂PPh₂). The reactivity of 1 as well as the activated complexes 2 a – c towards phenylethyne was studied. Thus 1 , 2 a and 2 b , respectively, react with PhC≡CH in refluxing toluene with elimination of dihydrogen to the acetylide‐bridged complexes [Ru₂(CO)₄(μ‐η¹ : η²‐C≡CPh)(μ‐P^tBu₂)(μ‐dppm)] ( 3 ) and [Ru₂(CO)₃L(μ‐η¹ : η²‐C≡CPh)(μ‐P^tBu₂)(μ‐dppm)] ( 4 a and 4 b ). The molecular structures of 3 and 4 a were determined by crystal structure analyses.     

Dimethyldioxirane as a new and effective oxidation agent for the epoxidation of α,ω‐di(isobutenyl)polyisobutylene: A convenient synthesis of α,ω‐di(2‐methyl‐3‐hydroxypropyl)‐polyisobutylene

The synthesis and characterization of α,ω‐di(2‐methyl‐2,3‐epoxypropyl)polyisobutylene are reported. The epoxidation of α,ω‐di(isobutenyl)polyisobutylene was achieved at room temperature with dimethyldioxirane, which proved to be a very effective reagent for epoxidation without the formation of byproducts. A very good agreement was found for the conversion determined by ¹H NMR and matrix‐assisted laser desorption/ionization mass spectrometry (MALDI HMS). The epoxy end groups were converted quantitatively into aldehyde termini with zinc bromide as a catalyst. The aldehyde groups were then reduced with LiAlH₄ into primary hydroxyl functions to obtain α,ω‐di(2‐methyl‐3‐hydroxylpropyl)polyisobutylene with high efficiency. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3974–3986, 2002     

Specifically π→π* Induced Photoreactions of α,β-Unsaturated Ketones: Hydrogen Abstraction by the α-carbon. (Preliminary Communication)

Irradiations at 254 nm of the α,β-unsaturated γ-dimethoxy-methyl ketone 7 in iso-octane and t-butyl alcohol afforded in a specifically π→π*induced process and in high chemical yield the epimeric products 9 and 10 . These products were not formed on n→π* excitation of 7 at > 340 nm, but triplet energy transfer to 1,3-cyclohexadiene could be observed. Photolyses of the hexadeuterio analog 7-d₆ at 254 nm led to the fully deuteriated products (cf. 9-d₆ ) in both solvents, with stereospecific incorporation of a deuterium atom in position C(1α). The structures of 9 and 10 were determined by an X-ray diffraction analysis of 9 and chemical correlations of the two products. The structural constraints in 7 demand a hitherto unprecedented direct transfer of a methoxyl hydrogen to the α-carbon of the excited enone and formation of intermediate 8 .     

Low‐Temperature Synthesis of Diamminesodium(1+) Triamminesodium(1+) Trithioantimonate(3−) Ammoniate (1 : 2 : 1 : 2) ([Na(NH3)3]2[Na(NH3)2]SbS3⋅2 NH3), A Solvated Neutral Sodium Trithioantimonate(3−) (3 : 1) Na3SbS3) Ion Complex

A solution of sodium in liquid ammonia reacts with Sb₂S₃ to form large colorless crystals of the composition Na₃SbS₃⋅10 NH₃. The trigonal‐pyramidal SbS₃³⁻ anion is ion‐paired with three Na⁺ counter ions, the coordination spheres of which are completed by eight ammine ligands. The resulting neutral [Na(NH₃)₃]₂[Na(NH₃)₂]SbS₃ molecules crystallize together with two ammonia molecules of solvation in the space group P2₁/c (a=9.828(2), b=6.0702(4), c=33.4377(6) Å, β=91.362(7)°, V=1994.2(5) ų, Z=4).     

π–π Dimerization of a mono(pyridyl–imine) platinum(II) chelate

The cation of the title complex salt, chlorido{2,2‐dimethyl‐N‐[(E)‐1‐(pyridin‐2‐yl)ethylidene]propane‐1,3‐diamine}platinum(II) tetrafluoridoborate, [PtCl(C₁₂H₁₉N₃)]BF₄, exhibits a nominally square‐planar Pt^II ion coordinated to a chloride ion [Pt—Cl = 2.3046 (9) Å] and three unique N‐atom types, viz. pyridine, imine and amine, of the tridentate Schiff base ligand formed by the 1:1 condensation of 1‐(pyridin‐2‐yl)ethanone and 2,2‐dimethylpropane‐1,3‐diamine. The cations are π‐stacked in inversion‐related pairs (dimers), with a mean plane separation of 3.426 Å, an intradimer Pt...Pt separation of 5.0785 (6) Å and a lateral shift of 3.676 Å. The centroid (Cg) of the pyridine ring is positioned approximately over the Pt^II ion of the neighbouring cation (Pt...Cg = 3.503 Å).