Liberating hydrogen: Strong Lewis or Brønsted acids react with ammonia–borane (H3NBH3) to form an in situ boronium cation, resulting the formation of a mixture cyclic and acyclic BNHx oligomers liberation H2 (see scheme). A proposed mechanism is supported by examination reaction thermodynamics using density functional theory.

It isn't easy BN aromatic! 1,2-Dihydro-1,2-azaborine, a hybrid organic/inorganic benzene, is stable aromatic molecule with features that are distinct from its isoelectronic “organic” (benzene) and “inorganic” (borazine) counterparts. Experimental structural, spectroscopic, chemical data fully supported by high-level calculations. Detailed facts of importance to specialist readers published as ”Supporting Information”. Such documents peer-reviewed, but not copy-edited or typeset. They made...

Going full circle: Ammonia borane is a potential H2-releasing fuel. Polyborazylene, form of the spent fuel, can be regenerated efficiently in one-pot process by stepwise addition appropriate digesting and reducing agents. A unique feature this formation NH3, which retained some digested species. Detailed facts importance to specialist readers are published as "Supporting Information". Such documents peer-reviewed, but not copy-edited or typeset. They made available submitted authors. Please...

In situ(11)B NMR monitoring, computational modeling, and external trapping studies show that selectivity extent of H(2) release in metal-catalysed dehydrogenation ammonia borane, NH(3)BH(3), are determined by coordination reactive aminoborane, NH(2)BH(2), to the metal center.

Electronic structure calculations using various methods, up to the coupled-cluster CCSD(T) level, in conjunction with aug-cc-pVnZ basis sets n = D, T, and Q, extrapolated complete set limit, show that borane molecule (BH3) can act as an efficient bifunctional acid-base catalyst H2 elimination reactions of XHnYHn systems (X, Y C, B, N). Such a is needed generation from isoelectronic ethane amine compounds proceeds energy barrier much higher than X-Y bond energy. The asymptotic for release...

Thermochemical data calculated using ab initio molecular orbital theory are reported for 16 BxNxHy compounds with x = 2, 3 and y ≥ 2x. Accurate gas-phase heats of formation were obtained coupled cluster single double excitations perturbative triples (CCSD(T)) valence electron calculations extrapolated to the complete basis set (CBS) limit additional corrections including core/valence, scalar relativistic, spin−orbit predict atomization energies scaled harmonic frequencies correct zero point...

High-level electronic structure calculations have been used to map out the relevant portions of potential energy surfaces for release H2 from dimers ammonia borane, BH3NH3 (AB). Using correlation-consistent aug-cc-pVTZ basis set at second-order perturbation MP2 level, geometries stationary points were optimized. Relative energies computed these using coupled-cluster CCSD(T) theory with sets least up level and in some cases extrapolated complete limit. The results show that there are a number...

Thermochemical parameters of carbonic acid and the stationary points on neutral hydration pathways carbon dioxide, CO 2 + nH 2O --> H 2CO 3 ( n - 1)H 2O, with = 1, 2, 3, 4, were calculated using geometries optimized at MP2/aug-cc-pVTZ level. Coupled-cluster theory (CCSD(T)) energies extrapolated to complete basis set limit in most cases then used evaluate heats formation. A high energy barrier approximately 50 kcal/mol was predicted for addition one water molecule 1). This is lowered cyclic...

Aromatisch und doch anders: 1,2-Dihydro-1,2-azaborin, ein organisch/anorganisches Benzol, ist stabiles aromatisches Molekül, das sich dennoch von seinen isoelektronischen „organischen“ (Benzol) „anorganischen“ Analoga (Borazin) unterscheidet. Die experimentell ermittelten Struktur-, spektroskopischen chemischen Daten werden durch Rechnungen auf hohem Theorie-Niveau bestätigt.

Dabei kommt Wasserstoff heraus: Starke Lewis- oder Brønsted-Säuren erzeugen in situ aus dem Ammoniak-Boran-Komplex (H3NBH3) ein Boroniumkation, das unter Freisetzung von H2 zu einer Mischung cyclischen und acyclischen BNHx-Oligomeren reagiert (siehe Schema). Der vorgeschlagene Mechanismus wird durch Dichtefunktionalrechnungen zur Thermodynamik der Reaktion gestützt.

Thermochemical properties of a set small boron (Bn) and oxide (BnOm) clusters, with n = 1−4 m 0−3, their anions, the B42− dianion, were calculated by using coupled-cluster theory CCSD(T) calculations aug-cc-pVnZ (n D, T, Q, 5) basis sets extrapolated to complete limit additional corrections. Enthalpies formation, bond dissociation energies, singlet−triplet or doublet−quartet separation gaps, adiabatic electron affinities (EA), both vertical attachment detachment energies evaluated. The...

Heats of formation at 0 and 298 K are predicted for PF3, PF5, PF3O, SF2, SF4, SF6, SF2O, SF2O2, SF4O as well a number radicals derived from these stable compounds on the basis coupled cluster theory [CCSD(T)] calculations extrapolated to complete set limit. In order achieve near chemical accuracy (+/-1 kcal/mol), additional corrections were added binding energies based frozen core energies: correction core-valence effects, scalar relativistic first-order atomic spin-orbit vibrational...

Thermochemical parameters of the closo boron hydride BnHn2- dianions, with n=5-12, B3H8- and B11H14- anions, B5H9 B10H14 neutral species were predicted by high-level ab initio electronic structure calculations. Total atomization energies obtained from coupled-cluster CCSD(T)/complete basis set (CBS) extrapolated energies, plus additional corrections used to predict heats formation simplest BnHmy- in gas phase kcal/mol at 298 K: DeltaHf(B3H8-)=-23.1+/-1.0; DeltaHf(B5H52-)=119.4+/-1.5;...

Atomization energies at 0 K and heats of formation 298 are predicted for (CH3)H2N−BH3, (CH3)HN═BH2, (BH3)HN═CH2, (CH3)H2B−NH3, (CH3)HB═NH2, (NH3)HB═CH2, as well various molecules involved in the different bond-breaking processes, from coupled cluster theory (CCSD(T)) calculations. In order to achieve near-chemical accuracy (±1 kcal/mol), three corrections were added complete basis set binding based on frozen core CCSD(T) energies, core−valence, scalar relativistic, first-order atomic...

The gas-phase acidities of the 20 L-amino acids have been predicted at composite G3(MP2) level. A broad range structures neutral and anion were studied to determine lowest energy conformer. Excellent agreement is found with available experimental deprotonation enthalpies, calculated values are within error. We predict that tyrosine deprotonated CO(2)H site. Cysteine be SH but proton on shared S(-) Self-consistent reaction field (SCRF) calculations COSMO parametrization used pK(a)'s...

The heats of formation N(2)H, diazene (cis- and trans-N(2)H(2)), N(2)H(3), hydrazine (N(2)H(4)), as well their protonated species (diazenium, N(2)H(3)(+), hydrazinium, N(2)H(5)(+)), have been calculated by using high level electronic structure theory. Energies were coupled cluster theory with a perturbative treatment the triple excitations (CCSD(T)) employing augmented correlation consistent basis sets (aug-cc-pVnZ) up to quintuple-zeta, perform complete set extrapolation for energy....

Der Kreis schließt sich: Ammoniakboran ist ein potenzieller H2-freisetzender Brennstoff. Aus Polyborazylen, einer Form des verbrauchten Brennstoffs, lässt sich durch schrittweise Zugabe von abbauenden und reduzierenden Reagentien in einem Eintopfprozess H3B-NH3 regenerieren. Ein besonderes Merkmal dieses Prozesses die Bildung NH3, das einigen der Abbauprodukte fixiert wird. Detailed facts of importance to specialist readers are published as "Supporting Information". Such documents...

Heats of formation the lowest triplet state ethylene and ground ethylidene have been predicted by high level electronic structure calculations. Total atomization energies obtained from coupled-cluster CCSD(T) extrapolated to complete basis set limit using correlation consistent sets (CBS), plus additional corrections predict following heats in kcal/mol: Δ(C2H4,3A1) = 80.1 at 0 K 78.5 298 K, Δ(CH3CH,3A' ') 86.8 85.1 with an error less than ±1.0 kcal/mol. The vertical adiabatic singlet−triplet...

Potential energy surfaces for H2 release from hydrazine interacting with borane, alane, diborane, dialane and borane–alane were constructed MP2/aVTZ geometries zero point energies single at the CCSD(T)/aug-cc-pVTZ level. With one borane or alane molecule, barrier H2-loss of ∼38 30 kcal mol−1 does not compete B–N Al–N bond cleavage (∼30 ∼28 mol−1). The second molecule can play role a bifunctional catalyst. H2-elimination is reduced 38 to 23 mol−1, 20 in presence diborane dialane,...

The heats of formation for BN, HBNH, H2BNH2, and H3BNH3 their radicals, anions, cations, protonated species were predicted using the CCSD(T) method with correlation consistent basis sets extrapolated to complete set core−valence, scalar relativistic, spin−orbit, zero-point energy corrections. Chemical accuracy (±1 kcal/mol) is obtained these formation, allowing reliable results electron hydride affinities, ionization energies, basicities (neutral proton affinities), acidities (anion bond...

High level ab initio electronic structure calculations at the coupled cluster with a correction for triples extrapolated to complete basis set limit have been made thermodynamics of BrBrO(2), IIO(2), ClBrO(2), ClIO(2), and BrIO(2) isomers, as well various molecules involved in bond dissociation processes. Of BrBrO(2) BrOOBr is predicted be most stable by 8.5 9.3 kcal/mol compared BrOBrO 298 K, respectively. The weakest O-Br energy (BDE) 15.9 kcal/mol, it Br-Br 19.1 kcal/mol. smallest BDE...

Thermochemical parameters of three C(2)H(5)O* radicals derived from ethanol were reevaluated using coupled-cluster theory CCSD(T) calculations, with the aug-cc-pVnZ (n = D, T, Q) basis sets, that allow CC energies to be extrapolated at CBS limit. Theoretical results obtained for methanol and two CH(3)O* found agree within +/-0.5 kcal/mol experiment values. A set consistent values was determined its radicals: (a) heats formation (298 K) DeltaHf(C(2)H(5)OH) -56.4 +/- 0.8 (exptl: -56.21 0.12...

Thermochemical parameters of hydroxymethylene (HC:OH) and 1-hydroxyethylidene (CH3C:OH) were evaluated by using coupled-cluster, CCSD(T), theory, in conjunction with the augmented correlation consistent, aug-cc-pVnZ, basis sets, n = D, T, Q, 5, extrapolated to complete set limit. The predicted value at 298 K for Delta Hf(CH2O) is -26.0 +/- 1 kcal/mol, as compared an experimental -25.98 0.01 Hf(CH:OH) it 26.1 kcal/mol. hydroxymethylene-formaldehyde energy gap 52.1 0.5 singlet-triplet...