We report the first optimum geometries and harmonic vibrational frequencies for ring pentamer several water hexamer (prism, cage, cyclic two book) at coupled-cluster including single, double, full perturbative triple excitations (CCSD(T))/aug-cc-pVDZ level of theory. All five examined isomer minima previously reported by Møller-Plesset perturbation theory (MP2) are also on CCSD(T) potential energy surface (PES). In addition, all minimum structures n = 2–6 cluster isomers quite close to ones...

We establish a new estimate for the binding energy between two benzene molecules in parallel-displaced (PD) conformation by systematically converging (i) intra- and intermolecular geometry at minimum, (ii) expansion of orbital basis set, (iii) level electron correlation. The calculations were performed second-order Møller-Plesset perturbation (MP2) coupled cluster including singles, doubles, perturbative triples replacement [CCSD(T)] levels electronic structure theory. At both theory,...

The biradical character β (1 for an ideal biradical) is determined from multi-reference configuration interaction (MRCI) wavefunctions. Triatomics in the series FX2+ (X=O, S, Se, Te, Po) exhibit unusually high characters X=Te, Po (0.76<β<0.92), largest among homologous 18 valence electron molecules CX22−, NX2−, X3, and OX2. On same scale, of O3 just 0.19, whereas that C(CH2)3 0.97. As a service to our authors readers, this journal provides supporting information supplied by authors. Such...

We investigate the bonding mechanism in ozone (O3) and its sulfur-substituted analogues, SO2, OS2, S3. By analyzing their ground-state multireference configuration interaction wave functions, we demonstrate that these systems can be represented as a mixture of closed-shell structure with one half bonds between central terminal atoms an open-shell single bond two lone electrons on each atom (biradical). The biradical character (β) further emerges simple measure relative contribution those...

The diatomic neutral oxides and their ions, MO(0,+/-), M = Sc, Ti, Cr, Mn, have been studied through multireference configuration interaction coupled-cluster methods. With the purpose to paint a more comprehensive detailed picture on these not so easily tamed systems, we constructed complete potential energy curves for large number of states all MO(0,+/-)'s reporting structural spectroscopic properties. Our overall results are in very good agreement with the, general limited, experimental...

Through a variety of highly correlated methods combined with large basis sets we have studied the electronic structure FeO, FeO(+), and FeO(-). In particular, constructed complete potential energy curves for 48, 24, 4 states FeO(-) species, respectively, at multireference level theory. For all examined report energetics, common spectroscopic parameters, dipole moments. Overall our results are in good agreement experiment, but encountered as well interesting differences between experiment...

We report MP2 and Coupled Cluster Singles, Doubles, perturbative Triples [CCSD(T)] binding energies with basis sets up to pentuple zeta quality for the (H2O)m=2-6,8 water clusters. Our best CCSD(T)/Complete Basis Set (CBS) estimates are -4.99 ± 0.04 kcal/mol (dimer), -15.8 0.1 (trimer), -27.4 (tetramer), -35.9 0.3 (pentamer), -46.2 (prism hexamer), -45.9 (cage -45.4 (book -44.3 (ring -73.0 0.5 (D2d octamer), -72.9 (S4 octamer). have found that percentage of both uncorrected (De) set...

A chiral phosphoric acid catalyzed allenylboration reaction is reported. Homopropargyl alcohols with an internal alkyne unit were obtained in good yields high enantioselectivities under the developed conditions.

Abstract An enantioselective allenylation of aldehydes catalyzed by a chiral, nonracemic phosphoric acid was reported. Under the developed conditions, 1,1′‐disubstituted allenic alcohols were obtained in 64–98% yields with 88–99% ee. Computational studies conducted to probe origin asymmetric induction. Mechanistic suggest that pinacol moiety propargylboronate is critical enantioselectivity reaction supported experimental data. magnified image

The diatomic molecule vanadium oxide, VO, and its charged species VO+ VO- were studied by multireference coupled cluster methods in conjunction with large basis sets. investigation of 22 states the construction 21 full potential energy curves allowed for a detailed understanding electronic structure these species. Our best binding energies ground VO (X4Sigma-), (X3Sigma-), (X3Sigma-) De = 150, 138, 143 kcal/mol, respectively, harmony corresponding experimental values. For both all studied,...

We report the variation of binding energy Formic Acid Dimer with size basis set at Coupled Cluster iterative Singles, Doubles and perturbatively connected Triple replacements [CCSD(T)] level theory, estimate Complete Basis Set (CBS) limit, examine validity Superposition Error (BSSE)-correction for this quantity that was previously challenged by Kalescky, Kraka, Cremer (KKC) [J. Chem. Phys. 140, 084315 (2014)]. Our results indicate BSSE correction, including terms account substantial geometry...

We present quantum mechanical calculations of the collision-induced absorption spectra nitrogen molecules, using ab initio dipole moment and potential energy surfaces. Collision-induced are first calculated isotropic interaction approximation. Then, we improve upon these results by considering full anisotropic potential. also develop computationally less expensive coupled-states approximation for calculating validate this comparing to numerically exact close-coupling low energies. Angular...

Tetra-amino beryllium complexes and ions, Be(NH3)40,±, have a tetrahedral Be(NH3)42+ core with one, two, or three outer electrons orbiting its periphery. Our calculations reveal new class of molecular entities, solvated electron precursors, Aufbau rules (1s, 1p, 1d, 2s, 1f, 2p, 2d) that differ from their familiar hydrogenic counterparts resemble those jellium nuclear-shell models. The core's radial electrostatic potential suffices to reproduce the chief features ab initio results. Wave...

Abstract The electronic structure of the simplest Criegee intermediate, H 2 COO, is practically that a closed shell. On biradical scale ( β ), where 0 corresponds to pure shell and 1 biradical, its value only 0.10, suggesting ground state best described as C=O δ+ −O δ− zwitterion. However, this picture nearly inert contradicts rich reactivity in atmosphere. It shown mixing with first triplet excited state, which type C . −O−O , responsible for formation strongly bound products during...

Mass spectrometric analysis of the anionic products interaction between platinum atomic anions, Pt- , and methane, CH4 CD4 in a collision cell shows preferred generation [PtCH4 ]- [PtCD4 complexes low tendency toward dehydrogenation. is shown to be H-Pt-CH3- by synergy anion photoelectron spectroscopy quantum chemical calculations, implying rupture single C-H bond. The calculated reaction pathway accounts for observed selective activation methane . This study presents first example anion.

Mass spectrometric analysis of the anionic products interaction among Pt–, methane, and carbon dioxide shows that methane activation complex, H3C–Pt–H–, reacts with CO2 to form [H3C–Pt–H(CO2)]−. Two hydrogenation one C–C bond coupling are identified as isomers [H3C–Pt–H(CO2)]− by a synergy between anion photoelectron spectroscopy quantum chemical calculations. Mechanistic study reveals both CH4 activated Pt atom successive depletion negative charge on drives insertion into Pt–H Pt–C bonds...

Cu-catalyzed highly stereoselective and enantiodivergent syntheses of (Z)- or (E)-β,γ-unsaturated ketones from 1,3-butadienyl silanes are developed. The nature the silyl group dienes has a significant impact on stereo- enantioselectivity reactions. Under developed catalytic systems, reactions acyl fluorides with phenyldiemthylsilyl-substituted 1,3-diene gave (Z)-β,γ-unsaturated bearing an α-tertiary stereogenic center excellent enantioselectivities high Z-selectivities, where...

Dinitrogen fixation under ambient conditions remains a challenge in the field of catalytic chemistry due to inertness N2. Nitrogenases and heterogeneous solid catalysts have displayed remarkable performance conversion dinitrogen ammonia. By introduction molybdenum centers molecular complexes, one most azophilic metals transitional metal series, moderate ammonia yields been attained. Here, we present combined multiconfigurational/density functional theory study that addresses how ligand...

Using the coupled-cluster methodology and large correlation consistent basis sets, we have examined BX YBBY (1Σg+) molecules, where X = He, Ne, Ar, Kr, CO, CS, N2 Y N2. For B−X series constructed full potential energy curves reporting total energies, equilibrium geometries, binding also spectroscopic constants for diatomic sequence. The B−CO, B−CS, B−N2 ground states are of 4Σ- 2Π symmetries, respectively, with having remarkably strong energies respect to their adiabatic fragments. all...

High-valent Fe(iv)-oxo species have been found to be key oxidizing intermediates in the mechanisms of mononuclear iron heme and non-heme enzymes that can functionalize strong C-H bonds. Biomimetic molecular complexes successfully synthesized characterized, but their catalytic reactivity is typically lower than enzymatic analogues. The activation step proceeds through two competitive mechanisms, named σ- π-channels. We performed high-level wave function theory calculations on bare FeO2+ a...

Tetra-amino lithium and sodium complexes M(NH3) (M = Li, Na) have one or two electrons that occupy diffuse orbitals distributed chiefly outside the core. The lowest-energy 1s, 1p, 1d follow Aufbau principles found earlier for beryllium tetra-ammonia complexes. Two ground state M(NH3)4 can bind covalently by coupling their 1s1 into a σ-type molecular orbital. lowest excited states of [M(NH3)4]2 species are obtained promoting from this σ to other bonding anti-bonding π-type orbitals....

Low-energy electrons dissolved in liquid ammonia or aqueous media are powerful reducing agents that promote challenging reduction reactions but can also cause radiation damage to biological tissue. Knowledge of the underlying mechanistic processes remains incomplete, particularly with respect details and energetics electron transfer steps. In this work, we show how ultraviolet (UV) photoexcitation metal-ammonia clusters could be used generate tunable low-energy situ. Specifically, identified...

Urea is a key molecule in the search for origin of life and basic chemical produced large quantities by industry. Its formation from ammonia carbon dioxide requires either high pressures temperatures or, under milder conditions, catalysts or additional reagents. Here we report spontaneous urea ambient conditions surface layer aqueous droplets. Single optically-trapped droplets were probed using Raman bands as markers. We found to act like microscopic flow reactor with gradients providing...

Alkyl substituted nitrogen heterocycles are important building blocks in drug molecules, agrochemicals, and materials. Herein we report a simple efficient way to prepare such compounds by coupling alkyl halides with heteroarenium salts. Detailed experimental computational studies indicate that this reaction goes through radical avoids the formation of undesired homocoupling salts via recycling dimers C–C bond cleavage under blue light.