An ab initio study of intermolecular interactions of nitromethane dimer and nitromethane trimer

Different geometries of nitromethane dimer and nitromethane trimer have been fully optimized employing the density functional theory B3LYP method and the 6-31++G** basis set. Three-body interaction energy has been obtained with the ab initio supermolecular approach at the levels of MP2/6-31++G**//B3LYP/6-31++G** and MP2/aug-cc-pVDZ//B3LYP/6-31++G**. The internal rotation of methyl group induced by intermolecular interaction has been observed theoretically. For the optimized structures of nitromethane dimer, the strength of C--H...O--N H-bond ranges from -9.0 to -12.4 kJ mol(-1) at the MP2/aug-cc-pVDZ//B3LYP/6-31++G** level, and the B3LYP method underestimates the interaction strength compared with the MP2 method, while MP2/6-31++G**//B3LYP/6-31++G** calculated DeltaE(C) is within 2.5 kJ mol(-1) of the corresponding value at the MP4(SDTQ)/6-31G**//B3LYP/6-31++G** level. The analytic atom-atom intermolecular potential has been successfully regressed by using the MP2/6-31++G**//B3LYP/6-31++G** calculated interaction energies of nitromethane dimer. For the optimized structures of nitromethane trimer the three-body interaction energies occupy small percentage of corresponding total binding energies, but become important for the compressed nitromethane explosive. In addition, it has been discovered that the three-body interaction energy in the cyclic nitromethane trimer is more and more negative as intermolecular distances decrease from 2.2 to 1.7 A.     

Acid-base interactions of benzo-annelated porphyrazines in proton-donor media

Acid-base interactions of benzo-annelated trifluoromethylphenylporphyrazines in media based on acetic and trifluoroacetic acids were studied. The quantitative characteristics of the equilibria between acid-base species were obtained. Variation of the porphyrazine structure leads to changes not only in the macroring basicity, but also in the structure and order of formation of acidic species depending on the nature of the proton-donor medium.     

Acid-base interactions in the methanesulfonic acid-propylene carbonate system

The methanesulfonic acid (MSA)—propylene carbonate (PC) system with component concentrations of 0–100% was studied at 30°C using the Multiple Attenuated Total Reflection (MATR) IR spectroscopy. The formation of a strong 1∶1 molecular complex of MSA with PC was established. In the presence of an excess of the acid, a second MSA molecule adds to this complex to give the molecular complex (2MSA)·PC. When excess propylene carbonate is used, the MSA·PC complex is solvated by a propylene carbonate molecule. No protonation of the base or formation of complexes with a strong symmetrical H bond was observed. Continuous absorption was not detected in IR spectra of the solutions. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 313–318 February, 1999.     

Acid-base interactions of benzoannelated porphyrazines in a dichloromethane-trifluoroacetic acid solution

Acid-base interactions of benzoannelated trifluoromethylphenylporphyrazines in a CH₂Cl₂-CF₃COOH medium were studied. The stability constants of the acid forms were determined and assumptions were made concerning their structure. It was shown that successive introduction of benzene rings into a porphyrazine molecule enhances the macrocycle basicity.     

Acid-base interactions of complexes of substituted triazoloporphyrazines in media containing acetic acids

Acid-base interactions of Cu(II) and Ni(II) complexes of substituted triazoloporphyrazines in benzene-AcOH and dichloromethane-AcOH mixtures were studied and quantitative characteristics of equilibria were obtained. The replacement of one pyrrole ring in porphyrazine molecule by triazole ring was shown to increase the basicity of a macrocycle; the N(1) atom of triazole ring was proposed to be the center of protonation.     

Studies on interactions of ions with nitromethane and acetonitrile using CNDO/force method

CNDO/force calculations on the complexes of nitromethane and acetonitrile with H⁺, Li⁺, F⁻ and Cl⁻ have been carried out to determine their geometrical parameters and stretching force constants. The results are discussed in terms of specific interactions between the ions and the molecules.     

Prenylation of olefins in nitromethane

The prenylation of isopentenyl and 3,3-dimethylallyl derivatives could be achieved effeciently with dimethyl, vinyl carbinol and a variety of acids in nitromethane. Geraniol and isopentenylacetate led to farnesyl derivatives.     

Mass spectrum of nitromethane

The mass spectrum of nitromethane points to rupture of the CH₃? NO₂ bond as the dominant primary reaction, as also observed in pyrolysis, photolysis and radiolysis. Isomerization of the molecular ion to the nitrite configuration seems to contribute little in the mass spectrum of nitromethane, in contrast to those of nitrobenzene and other nitroarenes. The nitrite ion is probably the immediate precursor of [NO]⁺ at its appearance potential, but most of the [NO]+ yield seems to stem from secondary decomposition of excited [NO₂]⁺.     

Acid-base interactions and adhesion capacity in the system constituted by an epoxy coating and a metal

Free surface energy and acidity parameter of solid surfaces of polyepoxides used as anticorrosive coatings were measured. Formulations of epoxy resins with various curing agents were studied. The adhesion capacity of epoxy films to various metallic surfaces was evaluated.     

The boron trifluoride nitromethane adduct

The separation of the boron isotopes using boron trifluoride·organic-donor, Lewis acid·base adducts is an essential first step in preparing ¹⁰B enriched and depleted crystalline solids so vital to nuclear studies and reactor applications such as enriched MgB₂, boron carbide, ZrB₂, HfB₂, aluminum boron alloys, and depleted silicon circuits for radiation hardening and neutron diffraction crystal structure studies. The appearance of this new adduct with such superior properties demands attention in the continuing search for more effective and efficient means of separation. An evaluation of the boron trifluoride nitromethane adduct, its thermodynamic and physical properties related to large-scale isotopic separation is presented. Its remarkably high separation factor was confirmed to be higher than the expected theoretical value. However, the reportedly high acid/donor ratio was proven to be an order of magnitude lower. On-going research is determining the crystal structure of deuterated and ¹¹B enriched ¹¹BF₃·CD₃NO₂ by X-ray and neutron diffraction.     

Esters of nitromethane nitronic acid

Russian Chemical Bulletin - For the first time, O-methyl and O-ethyl esters of dinitromethane were isolated in an individual state. Their structures were confirmed by spectral methods, elemental...     

Carbamate preparation by nitromethane carbonylation

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, p. 1190, May, 1988.