Reactions of Diethylazo-Dicarboxylate with Frustrated Lewis Pairs.

Reactions of PAr /B(C F ) (Ar=o-Tol, Mes, Ph) FLPs with diethyl azodicarboxylate (DEAD) afford the corresponding FLP addition products 1-3 in which P-N and B-O linkages are formed. In contrast, the reaction of BPh , PPh and DEAD gave product 4 where P-N and N-B linkages were confirmed. In all cases, other binding modes were computed to be both higher in energy and readily distinguishable by P and B NMR parameters.

Catalyst-free CO hydrogenation with BHNH in water: DFT mechanistic insights.

Extensive DFT calculations show that BHNH may transfer dihydrogen as separated hydride and proton to CO rather than HCO in water over a barrier of 25.9 kcal mol, followed by faster hydride transfer from borate anions to either electrophilic CO or protic HO or HCOH, leading to competitive formate production and H release.

Exploiting Phase Transitions in Catalysis: Adsorption of CO on doped VO -Polymorphs.

VO is well known for its low-temperature metal-insulator transition between two phases with tetragonal rutile and monoclinic structure. The adsorption of CO on the two polymorphs of Mo-doped VO is calculated to investigate the effect of a substrate phase change on the adsorption energy. The system is investigated theoretically at density-functional theory level using a hybrid functional with London dispersion correction.

Optimization of the rSCAN-3c Composite Electronic-Structure Method for Use with Slater-Type Orbital Basis Sets.

The "Swiss army knife" composite density functional electronic-structure method rSCAN-3c ( , , 064103) is extended and optimized for the use with Slater-type orbital basis sets. The meta generalized-gradient approximation (meta-GGA) functional rSCAN by Furness et al. is combined with a tailor-made polarized triple-ζ Slater-type atomic orbital (STO) basis set (mTZ2P), the semiclassical London dispersion correction (D4), and a geometrical counterpoise (gCP) correction.

Effect of Doping on Rutile TiO Surface Stability and Crystal Shapes.

Transition-metal-(TM-)doped TiO has been considered as promising electrode material for the oxygen evolution reaction (OER). OER activity is expected to depend on the coordination of the surface atoms. In this study, we theoretically investigate the stability of low-index surfaces of TM-doped rutile, (110), (100), (101) and (001), with 50 % of the Ti atoms substituted by Sc, Y, V, Nb or Ta.

Conformational Energy Benchmark for Longer -Alkane Chains.

We present the first benchmark set focusing on the conformational energies of highly flexible, long -alkane chains, termed ACONFL. Unbranched alkanes are ubiquitous building blocks in nature, so the goal is to be able to calculate their properties most accurately to improve the modeling of, e.g.

The Role of Packing, Dispersion, Electrostatics, and Solvation in High-Affinity Complexes of Cucurbit[n]urils with Uncharged Polar Guests.

The rationalization of non-covalent binding trends is both of fundamental interest and provides new design concepts for biomimetic molecular systems. Cucurbit[n]urils (CBn) are known for a long time as the strongest synthetic binders for a wide range of (bio)organic compounds in water. However, their host-guest binding mechanism remains ambiguous despite their symmetric and simple macrocyclic structure and the wealth of literature reports.

Towards understanding solvation effects on the conformational entropy of non-rigid molecules.

The absolute molecular entropy is a fundamental quantity for the accurate description of thermodynamic properties. For non-rigid molecules, a substantial part of the entropy can be attributed to a conformational contribution. Systems and properties where this is relevant, , protein-ligand binding affinities or p values refer usually to the liquid phase.

Automated Molecular Cluster Growing for Explicit Solvation by Efficient Force Field and Tight Binding Methods.

An automated and broadly applicable workflow for the description of solvation effects in an explicit manner is introduced. This method, termed quantum cluster growth (QCG), is based on the semiempirical GFN2-xTB/GFN-FF methods, enabling efficient geometry optimizations and MD simulations. Fast structure generation is provided using the intermolecular force field xTB-IFF.

Computational study of ground-state properties of μ -bridged group 14 porphyrinic sandwich complexes.

The structural properties of μ -bridged porphyrinic double-decker complexes are investigated and the influence of various ligands, metals, substituents, and bridging atoms on the dominant structural motif is elucidated. A variety of quantum chemical methods including semiempirical (SQM) methods and density functional theory (DFT) is assessed for the calculation of ecliptic and staggered conformational energies. Local coupled cluster (DLPNO-CCSD(T1)) data are generated for reference.

Dispersion corrected rSCAN based global hybrid functionals: rSCANh, rSCAN0, and rSCAN50.

The regularized and restored semilocal meta-generalized gradient approximation (meta-GGA) exchange-correlation functional rSCAN [Furness et al., J. Phys.

Effect of cation configuration and solvation on the band positions of zinc ferrite (100).

Zinc ferrite ZnFe[Formula: see text]O[Formula: see text] belongs to the spinel-type ferrites that have been proposed as photocatalysts for water splitting. The electronic band gap and the band edge positions are of utmost importance for the efficiency of the photocatalytic processes. We, therefore, calculated the absolute band energies of the most stable surface of ZnFe[Formula: see text]O[Formula: see text], the Zn-terminated (100) surface at self-consistent hybrid density functional theory level.

Intermolecular Carbosilylation of α-Olefins with C(sp )-C(sp) Bond Formation Involving Silylium-Ion Regeneration.

A regioselective addition of alkynylsilanes across unactivated, terminal alkenes is reported. The reaction is initiated by the capture of a sterically unhindered silylium ion by a silylated phenylacetylene derivative to form a bis(silylated) ketene-like carbocation. This in situ-generated key intermediate is the actual catalyst that maintains the catalytic cycle by a series of electrophilic addition reactions of silylium ions and β-silicon-stabilized carbocations.

BSSE-corrected consistent Gaussian basis sets of triple-zeta valence with polarization quality of the fifth period for solid-state calculations.

Revised versions of our published pob-TZVP basis sets [Laun, J.; Vilela Oliveira, D. and Bredow, T.

The Non-Ancillary Nature of Trimethylsilylamide Substituents in Boranes and Borinium Cations.

The known boranes (R(Me Si)N) BF (R=Me Si 1, tBu 2, C F 3, o-tol 4, Mes 5, Dipp 6) and borinium salts (R(Me Si)N) B][B(C F ) ] (R=Me Si 7, tBu 8) are prepared and fully characterized. Compound 7 is shown to react with phosphines to generate [R PSiMe ] and [R PH] (R=Me, tBu). Efforts to generate related borinium cations via fluoride abstraction from (R(Me Si)N) BF (R=C F 3, o-tol 4, Mes 5) gave complex mixtures suggesting multiple reaction pathways.

The Varied Frustrated Lewis Pair Reactivity of the Germylene Phosphaketene (CH{(CMe)(2,6- Pr C H N)} )GePCO.

The germylene species (CH{(CMe)(2,6-iPr C H N)} )GePCO 1 is shown to react with the Lewis acids (E(C F ) E=B, Al). Nonetheless, 1 participates in FLP chemistry with electron deficient alkynes or olefins, acting as an intramolecular FLP. In contrast, in the presence of B(C F ) and an electron rich alkyne, 1 behaves as Ge-based nucleophile to effect intermolecular FLP addition to the alkyne.

Photocatalytic H production and degradation of aqueous 2-chlorophenol over B/N-graphene-coated Cu/TiO: A DFT, experimental and mechanistic investigation.

Energy and environmental challenges are global concerns that scientists are interested in alleviating. It is on this premise that we prepared boron/nitrogen graphene-coated Cu/TiO (B/N-graphene-coated Cu/TiO) photocatalyst of varying B:N ratios with dual functionality of H production and 2-Chlorophenol (2-CP) degradation. In-situ coating of Cu with B/N-graphene is achieved via solvothermal synthesis and calcination under an inert atmosphere.

Quantum Chemistry-based Molecular Dynamics Simulations as a Tool for the Assignment of ESI-MS/MS Spectra of Drug Molecules.

In organic mass spectrometry, fragment ions provide important information on the analyte as a central part of its structure elucidation. With increasing molecular size and possible protonation sites, the potential energy surface (PES) of the analyte can become very complex, which results in a large number of possible fragmentation patterns. Quantum chemical (QC) calculations can help here, enabling the fast calculation of the PES and thus enhancing the mass spectrometry-based structure elucidation processes.

The long-awaited synthesis and self-assembly of a small rigid -symmetric trilactam.

The challenging synthesis of a fused -symmetric trilactam (1) was executed in racemic and enantiomerically pure form. The rigidity, symmetry and high density of hydrogen bonding motifs make 1 an attractive candidate for self-assembly study, which revealed different hydrogen bond patterns in the crystals of -1- and (+)-()-1.

The Ionic Product of Water in the Eye of the Quantum Cluster Equilibrium.

The theoretical description of water properties continues to be a challenge. Using quantum cluster equilibrium (QCE) theory, we combine state-of-the-art quantum chemistry and statistical thermodynamic methods with the almost historical Clausius-Clapeyron relation to study water self-dissociation and the thermodynamics of vaporization. We pay particular attention to the treatment of internal rotations and their impact on the investigated properties by employing the modified rigid-rotor-harmonic-oscillator (mRRHO) approach.

Ionic Liquid-Based Low-Temperature Synthesis of Crystalline Ti(OH)OF·0.66HO: Elucidating the Molecular Reaction Steps by NMR Spectroscopy and Theoretical Studies.

We present an in-depth mechanistic study of the first steps of the solution-based synthesis of the peculiar hexagonal tungsten bronze-type Ti(OH)OF·0.66HO solid, using NMR analyses (H, C, F, and B) as well as modeling based on density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulation. The reaction uses an imidazolium-based ionic liquid (IL, e.

Benchmark Study on the Calculation of Sn NMR Chemical Shifts.

A new benchmark set termed for assessing quantum chemical methods for the computation of Sn NMR chemical shifts is presented. It covers 51 unique Sn NMR chemical shifts for a selection of 50 tin compounds with diverse bonding motifs and ligands. The experimental reference data are in the spectral range of ±2500 ppm measured in seven different solvents.

Stereochemical Behavior of Pairs of P-stereogenic Phosphanyl Groups at the Dimethylxanthene Backbone.

The P-stereogenic bis(phosphanes) 7 and 9, featuring pairs of P(Mes)-ethynyl or vinyl substituents at the dimethyl xanthene backbone show rather low barriers of stereochemical inversion at phosphorus. π-Conjugative effects are probably causing these low inversion barriers. Compound 7 reacted with B(C F ) to form the nine-membered heterocyclic product 10, featuring a [P]-C≡C-B(C F ) substituent.

Hydrocarbon Macrocycle Conformer Ensembles and C-NMR Spectra.

NMR as a routine analytical method provides important three-dimensional structure information of compounds in solution. Here we apply the recently released CRENSO computational workflow for the automated generation of conformer ensembles to the quantum mechanical calculation of C-NMR spectra of a series of flexible cycloalkanes up to C H . We evaluate the computed chemical shifts in comparison with corresponding experimental data in chloroform.

A New Oxygen Containing Pyclen-Type Ligand as a Manganese(II) Binder for MRI and Mn PET Applications: Equilibrium, Kinetic, Relaxometric, Structural and Radiochemical Studies.

A new pyclen-3,9-diacetate derivative ligand (H) was synthesized possessing an etheric O-atom opposite to the pyridine ring, to improve the dissociation kinetics of its Mn(II) complex (pyclen = 3,6,9,15-tetraazabicyclo(9.3.1)pentadeca-1(15),11,13-triene).