Theoretical description of halogen bonding : an insight based on the natural orbitals for chemical valence combined with the extended-transition-state method (ETS-NOCV)

In the present study we have characterized the halogen bonding in selected molecules H 3 N – ICF 3 ( 1- NH 3 ), (PH 3 ) 2 C – ICF 3 ( 1-CPH 3 ), C 3 H 7 Br – (IN 2 H 2 C 3 ) 2 C 6 H 4 ( 2-Br ), H 2 – (IN 2 H 2 C 3 ) 2 C 6 H 4 ( 2-H 2 ) and Cl – (IC 6 F 5 ) 2 C 7 H 10 N 2 O 5 ( 3-Cl) , containing from one halogen bond ( 1-NH 3 , 1-CPH 3 ) up to four connections in 3-Cl (the two Cl – HN and two Cl – I), based on recently proposed ETS- NOCV analysis. It was found based on the NOCV- deformation density components that the halogen bonding C – X ... B (X-halogen atom, B-Lewis base), contains a large degree of covalent contribution (the charge transfer to X ... B inter-atomic region) supported further by the electron dona- tion from base atom B to the empty σ *(C – X) orbital. Such charge transfers can be of similar importance compared to the electrostatic stabilization. Further, the covalent part of halogen bonding is due to the presence of σ -hole at outer part of halogen atom (X). ETS-NOCV approach allowed to visualize formation of the σ -hole at iodine atom of CF 3 I molecule. It has also been demonstrated that strongly elec- trophilic halogen bond donor, [C 6 H 4 (C 3 H 2 N 2 I) 2 ][OTf] 2 , can activate chemically inert isopropyl bromide ( 2-Br ) moiety via formation of Br – I bonding and bind the hydrogen mol- ecule ( 2-H 2 ). Finally, ETS-NOCVanalysis performed for 3- Cl leads to the conclusion that, in terms of the orbital- interaction component, the strength of halogen (Cl – I) bond is roughly three times more important than the hydrogen bonding (Cl – HN)

Common defence – the past or the future?

The contents of the doctrines at the operational and tactical levels focus primarily on the ways in which the components of the types of armed forces are used and the for cooperation between them. Documents of a higher level (e.g. strategies) indicate a number of threats, including non-military ones, affecting the state directly or indirectly. The issue of using social potential in these documents is marginalised. Lessons from the Russian- Ukrainian war emphasise how important the role of common defence is for the defence of the country against aggression. Nowadays, however, common defence cannot be “limited” to military action alone. A potential opponent is not only its army, but also its society, economy, culture, etc. The research conducted and its results point to opportunities to increase the defence impact of the state through effective and full use of its actors, including the military

ETS-NOCV description of σ-hole bonding

The ETS-NOCVanalysis was applied to describe the σ -hole in a systematic way in a series of halogen com- pounds, CF 3 -X ( X 0 I, Br, Cl, F), CH 3 I, and C(CH3) n H 3-n -I ( n 0 1,2,3), as well as for the example germanium-based systems. GeXH 3 , X 0 F,Cl,H.Further,theETS-NOCV analysis was used to characterize bonding with ammonia for these systems. The results show that the dominating contribution to the deformation density, Δ ρ 1 , exhibits the negative-value area with a minimum, corresponding to σ - hole. The “ size ” (spatial extension of negative value) and “ depth ” (minium value) of the σ -hole varies for different X in CF 3 -X, and is influenced by the carbon substituents (fluorine atoms, hydrogen atoms, methyl groups). The size and depth of σ -hole decreases in the order: I, Br, Cl, F in CF 3 -X. In CH 3 -I and C(CH3) n H 3-n -I, compared to CF 3 -I, introduction of hydrogen atoms and their subsequent replacements by methyl groups lead to the systematic de- crease in the σ -hole size and depth. The ETS-NOCV σ -hole picture is consistent with the existence the positive MEP area at the extension of σ -hole generating bond. Finally, the NOCV deformation density contours as well as by the ETS orbital-interaction e nergy indicate that the σ -hole-based bond with ammonia contains a degree of covalent contribu- tion. In all analyzed systems, it was found that the electro- static energy is approximately two times larger than the orbital-interaction term, confirming the indisputable role of the electrostatic stabilization in halogen bonding and σ -hole bonding

Palladium Catalysts for Dehydrogenation of Ammonia Borane with Preferential B−H Activation

Cationic Pd(II) complexes catalyzed the dehydrogenation of ammonia borane in the most efficient manner with the release of 2.0 equiv of H_2 in less than 60 s at 25 °C. Most of the hydrogen atoms were obtained from the boron atom of the ammonia borane. The first step of the dehydrogenation reaction was elaborated using density functional theory calculations

Dehydrogenation of ammonia-borane by cationic Pd(II) and Ni(II) complexes in a nitromethane medium: hydrogen release and spent fuel characterization

A highly electrophilic cationic PdII complex, [Pd(MeCN)_4][BF_4]_2 (1), brings about the preferential activation of the B–H bond in ammonia-borane (NH3·BH3, AB). At room temperature, the reaction between 1 in CH_3NO_2 and AB in tetraglyme leads to Pd nanoparticles and formation of spent fuels of the general formula MeNH_xBO_y as reaction byproducts, while 2 equiv. of H_2 is efficiently released per AB equiv. at room temperature within 60 seconds. For a mechanistic understanding of dehydrogenation by 1, the chemical structures of spent fuels were intensely characterized by a series of analyses such as elemental analysis (EA), X-ray photoelectron spectroscopy (XPS), solid state magic-angle-spinning (MAS) NMR spectra (^2H, ^(13)C, ^(15)N, and ^(11)B), and cross polarization (CP) MAS methods. During AB dehydrogenation, the involvement of MeNO2 in the spent fuels showed that the mechanism of dehydrogenation catalyzed by 1 is different from that found in the previously reported results. This AB dehydrogenation derived from MeNO_2 is supported by a subsequent digestion experiment of the AB spent fuel: B(OMe)_3 and N-methylhydroxylamine ([Me(OH)N]_2CH_2), which are formed by the methanolysis of the AB spent fuel (MeNH_xBO_y), were identified by means of ^(11)B NMR and single crystal structural analysis, respectively. A similar catalytic behavior was also observed in the AB dehydrogenation catalyzed by a nickel catalyst, [Ni(MeCN)_6][BF_4]_2 (2)

The comparison of Kardia Mobile and Hartmann Veroval 2 in 1 in detecting first diagnosed atrial fibrillation

Background: Atrial fibrillation (AF) is the leading cause of stroke. The European Society of Cardiology (ESC) advises opportunistic AF screening among patients aged ≥ 65 years. Considering this, the aim herein, was compare the feasibility of two different systems of smartphone-based electrocardiogram (ECG) recordings to identify AF among those without a previous arrhythmia history. Methods: Prospective AF screening was conducted at six pharmacies using Kardia Mobile and Hartmann Veroval 2 in 1. A single-lead ECG was acquired by the placement of fingers on the pads. A cardiologist evaluated findings from both devices. Results: Atrial fibrillation was identified in 3.60% and previously unknown AF was detected in 1.92% of the study participants. Sensitivity and specificity of the Kardia application in detecting AF were 66.7% (95% confidence interval [CI] 38.4–88.2%) and 98.5% (95% CI 96.7–99.5%), and for Veroval 10.0% (95% CI 0.23–44.5%) and 94.96% (95% CI 92.15–96.98%), accordingly. Inter-rater agreement was k = 0.088 (95% CI 1.59–16.1%). Conclusions: Mobile devices can detect AF, but each finding must be verified by a professional. The Kardia application appeared to be more user-friendly than Veroval. Cardiovascular screening using mobile devices is feasible at pharmacies. Hence it might be considered for routine use