Revisiting the role of octahedral symmetry in the interpretation of spectroscopic properties of [OsF] and PtF complexes.

The electronic structure of [OsF] and PtF complexes was studied by means of CASSCF/NEVPT2 multiconfigurational calculations, including spin-orbital coupling, which is very relevant in the case of these metals. From these calculations, it is possible to establish that in the octahedral symmetry (), the ground state is non-magnetic ( = 0) because of the strong ligand field, and the interaction with paramagnetic excited states is almost negligible, resulting in a non-magnetic behavior, which is in agreement with the experimental evidence.

Mobile genetic elements drive the multidrug resistance and spread of serotypes along a poultry meat production line.

The presence of mobile genetic elements in isolated from a chicken farm constitutes a potential risk for the appearance of emerging bacteria present in the food industry. These elements contribute to increased pathogenicity and antimicrobial resistance through genes that are related to the formation of biofilms and resistance genes contained in plasmids, integrons, and transposons. One hundred and thirty-three isolates from different stages of the production line, such as feed manufacturing, hatchery, broiler farm, poultry farm, and slaughterhouse, were identified, serotyped and sequenced.

Genetic Characterization of Infantis with Multiple Drug Resistance Profiles Isolated from a Poultry-Farm in Chile.

comprises over 2500 serotypes and foodborne contamination associated with this pathogen remains an important health concern worldwide. During the last decade, a shift in serotype prevalence has occurred as traditionally less prevalent serotypes are increasing in frequency of infections, especially those related to poultry meat contamination. Infantis is one of the major emerging serotypes, and these strains commonly display antimicrobial resistance and can persist despite cleaning protocols.

Relativistic effects on the aromaticity of EMH (E = C-Pb; M = N-Bi) benzene analogues.

The relativistic effects on the aromaticity of a set of benzene analogues, E3M3H3 (E = C-Pb; M = N-Bi) heterocycles, using magnetically induced current density (MICD) and the NICSzz component of the conventional nucleus independent chemical shift (NICS), is hereby examined. The relativistic effects were evaluated by means of four-component relativistic MICD, and two-component NMR relativistic shielding tensor methods. MICD and NICS were also computed in a non-relativistic fashion, to assess the influence of scalar-relativistic and spin-orbit effects.

Spin-orbit effects on magnetically induced current densities in the M5- (M = N,P,As,Sb,Bi,Mc) clusters.

This study reports the spin-orbit effects on the aromaticity of the N5-, P5-, As5-, Sb5-, Bi5-, and Mc5- anionic clusters via the magnetically induced current-density method. All-electron density functional theory (DFT) calculations were carried out using the four-component Dirac-Coulomb (DC) hamiltonian, including scalar and spin-orbit relativistic effects. The magnetic index of aromaticity was calculated by numerical integration over the current flow between two atoms in the pentagonal ring.

Information on Gas-Phase Diatomic Molecules from Magnetically Induced Current Densities.

Magnetically induced current densities are different for different types of chemical bonds, and may help highlight some of their characteristics and stress their main differences. The present work considers magnetically induced current densities in the bonds of diatomic molecules bonded by covalent bonds as well as the gas phase molecules of 1:1 ionic compounds, comparing the current strength values and visualizing current density maps. The results show clear-cut differences for the different types of bonds (non-polar covalent, polar covalent, and ionic), and can also be related to the extent of the covalent or ionic character of a bond.

Relativistic effects on the aromaticity of the halogenated benzenes: C6X6, X = H, F, Cl, Br, I, At.

In this study we report about the relativistic effects on the aromaticity of the six hexahalogenated compounds (C6H6, C6F6, C6Cl6, C6Br6, C6I6 and C6At6), via a magnetically induced current density method. All-electron density functional theory (DFT) calculations were carried out using the four-component Dirac-Coulomb (DC) Hamiltonian, including scalar and spin-orbit (SO) relativistic effects. Fully relativistic values of the magnetically induced ring currents were obtained by numerical integration over the current flow.

New Insights into Re3(μ-Cl)3Cl6 Aromaticity. Evidence of σ- and π-Diatropicity.

We have theoretically evaluated the behavior of the Re3(μ-Cl)3Cl6 cluster under magnetic perturbation, and it clearly shows that the magnetic response within the Re3(μ-Cl)3 plane is highly diatropic in nature. An analysis of both the magnetically induced current density (MICD) and induced magnetic field (B(ind)) allows us to classify this cluster as doubly σ- and also π-aromatic on the magnetic criterion. These findings contradict the classical Re-Re double bond representation and favor a chemical bonding pattern that involves delocalized bonds.

Structural aspects of two α-dihydrazones displaying a complete survey of intermolecular interactions.

The compounds (2'E,2'E)-2,2'-(propane-1,2-diylidene)bis[1-(2-nitrophenyl)hydrazine], C15H14N6O4, (I), and (2Z,3Z)-ethyl 3-[2-(2-nitrophenyl)hydrazinylidene]-2-[2-(4-nitrophenyl)hydrazinylidene]butanoate tetrahydrofuran hemisolvate, C18H18N6O6·0.5C4H8O, (II), are puzzling outliers deviating from a general synthetic route aimed at the preparation of substituted pyrazoles. Possible reasons for this outcome, which is exceptional in an otherwise firmly established synthetic procedure, are analyzed.

Revisiting Aromaticity and Chemical Bonding of Fluorinated Benzene Derivatives.

The electron delocalization of benzene (C6H6) and hexafluorobenzene (C6F6) was analyzed in terms of the induced magnetic field, nucleus-independent chemical shift (NICS), and ring current strength (RCS). The computed out-of-plane component of the induced magnetic field at a distance (r) greater than or equal to 1.0 Å above the ring center correlates well (R (2)>0.

On substituted pyrazole derivatives. II. (E)-1-(4-{[1-(4-Fluorophenyl)-3,5-dimethyl-1H-pyrazol-4-yl]diazenyl}phenyl)ethanone and (E)-1-(4-chlorophenyl)-3,5-dimethyl-4-[2-(2-nitrophenyl)diazenyl]-1H-pyrazole.

The molecular structures of (E)-1-(4-{[1-(4-fluorophenyl)-3,5-dimethyl-1H-pyrazol-4-yl]diazenyl}phenyl)ethanone, C19H17FN4O, (III), and (E)-1-(4-chlorophenyl)-3,5-dimethyl-4-[2-(2-nitrophenyl)diazenyl]-1H-pyrazole, C17H14ClN5O2, (IV), prepared by reaction of the corresponding β-diketohydrazones with substituted arylhydrazines in acid media, are nonplanar, with the planes of the lateral phenyl rings forming dihedral angles with that of the central pyrazole ring varying from 2.71 (7) to 45.22 (7)°.

On substituted pyrazole derivatives. I. 3-Methyl-4-[(Z)-2-(4-methylphenyl)hydrazin-1-ylidene]-1-(3-nitrophenyl)-1H-pyrazol-5(4H)-one and 3-methyl-4-[(Z)-2-(4-methylphenyl)hydrazin-1-ylidene]-1-[4-(trifluoromethyl)phenyl]-1H-pyrazol-5(4H)-one.

The title substituted pyrazole derivatives, C17H15N5O3 and C18H15F3N4O, share most of their molecular features, in particular the hydrazinylidene (-HN-N=) rather than the diazene (-N=N-) tautomeric form, and differ only in the substituents (NO2 and CF3) on one of the outer phenyl rings. The molecular units are basically planar, with the rotation of the phenyl rings being hindered by the presence of two intramolecular hydrogen bonds having the keto O atom as acceptor. In both structures, the packing is governed by weak C-H.

Minimizing the risk of reporting false aromaticity and antiaromaticity in inorganic heterocycles following magnetic criteria.

Although aromaticity is a concept in chemistry, in the last years, special efforts have been carried out in order to propose theoretical strategies to quantify it as a property of molecular rings. Among them, perhaps the computation of nucleus independent chemical shifts (NICSs) is the most commonly used, since it is possible to calculate it in an easy and fast way with most used quantum chemistry software. However, contradicting assignments of aromaticity by NICS and other methods have been reported in the literature, especially in studies concerning inorganic chemistry.

Dimers linked by type-I C-F···F-C contacts in (Z)-3-methyl-4-[2-(4-methylphenyl)hydrazinylidene]-1-(pentafluorophenyl)-1H-pyrazol-5(4H)-one.

The title compound, C17H11F5N4O, is described and compared with two closely related analogues in the literature. There are two independent molecules in the asymmetric unit, linked by N-H···O hydrogen bonds and π-π interactions into dimeric entities, presenting a noticeable noncrystallographic C2 symmetry. These dimers are in turn linked by a medium-strength type-I C-F···F-C interaction into elongated tetramers.

3,5-Dimethyl-4-[(E)-(2-nitrophenyl)diazenyl]-1-(2,3,4,5,6-pentafluorophenyl)-1H-pyrazole.

The title compound, C(17)H(10)F(5)N(5)O(2), is described and compared with its 4-nitrophenyl isomer [Bustos, Sánchez, Schott, Alvarez-Thon & Fuentealba (2007). Acta Cryst. E63, o1138-o1139].

(Z)-1-(2-Chloro-phen-yl)-3-methyl-4-[2-(4-nitro-phen-yl)hydrazin-1-yl-idene]-1H-pyrazol-5(4H)-one.

There are two independent mol-ecules, A and B, in the asymmetric unit of the title compound, C(16)H(12)ClN(5)O(3). The relative orientations of the chloro-phenyl ring with respect to the pyrazole ring in the two crystallographically independent mol-ecules are different, and their corresponding dihedral angles are -53.3 (2) and 114.

(E)-3,5-Dimethyl-1-p-tolyl-4-(p-tolyl-diazen-yl)-1H-pyrazole.

There are two independent mol-ecules, A and B, in the asymmetric unit of the title compound, C(19)H(20)N(4), in each of which the N=N double bond has an E conformation. The dihedral angles between the pyrazole ring and the p-tolyl rings in the 1- and 4-positions are 22.54 (8) and 35.

2-[2-(4-Acetyl-phen-yl)hydrazinyl-idene]-1,3-diphenyl-propane-1,3-dione.

In the title compound, C(23)H(18)N(2)O(3), the inter-planar angle between the benzoyl units is 80.51 (6)° while the dihedral angles between the hydrazinyl-idene and benzoyl groups are 43.43 (6) and 54.

Probing the aromaticity of the [(H(t)Ac)3(μ2-H)6], [(H(t)Th)3(μ2-H)6],(+), and [(H(t)Pa)3(μ2-H)6] clusters.

In this study we report about the aromaticity of the prototypical [(H(t)Ac)(3)(μ(2)-H)(6)], [(H(t)Th)(3)(μ(2)-H)(6)](+), and [(H(t)Pa)(3)(μ(2)-H)(6)] clusters via two magnetic criteria: nucleus-independent chemical shifts (NICS) and the magnetically induced current density. All-electron density functional theory calculations were carried out using the two-component zeroth-order regular approach and the four-component Dirac-Coulomb Hamiltonian, including scalar and spin-orbit relativistic effects. Four-component current density maps and the integration of induced ring-current susceptibilities clearly show that the clusters [(H(t)Ac)(3)(μ(2)-H)(6)] and [(H(t)Th)(3)(μ(2)-H)(6)](+) are non-aromatic whereas [(H(t)Pa)(3)(μ(2)-H)(6)] is anti-aromatic.

A second monoclinic polymorph of 2-[2-(4-meth-oxy-phen-yl)hydrazinyl-idene]-1,3-diphenyl-propane-1,3-dione.

The title compound, C(22)H(18)N(2)O(3) is the second monoclinic polymorph (P2(1)/c) of the compound, the first being reported in space group P2(1) [Bertolasi et al. (1993 ▶). J.

2-[2-(4-Nitro-phen-yl)hydrazinyl-idene]-1,3-diphenyl-propane-1,3-dione.

In the mol-ecular structure of the title compound, C(21)H(15)N(3)O(4), the inter-planar angle between the benzoyl units is 89.7 (1)°. The corresponding angles between the phenyl-hydrazono and the benzoyl groups are 31.

2-[2-(3-Chloro-phen-yl)hydrazinyl-idene]-1,3-diphenyl-propane-1,3-dione.

The mol-ecular structure of the title compound, C(21)H(15)ClN(2)O(2), features one strong intra-molecular N-H⋯O resonance-assisted hydrogen bond (RAHB). In the crystal, mol-ecules form inversion-related dimers via pairs of weak inter-molecular N-H⋯O contacts. These dimers are further stabilized via three weak C-H⋯O contacts, developing the three-dimensional structure.

2-[2-(4-Bromo-phen-yl)hydrazinyl-idene]-1,3-diphenyl-propane-1,3-dione.

The conformation of the title mol-ecule, C(21)H(15)BrN(2)O(2), is stabilized by a weak intra-molecular C-H⋯N hydrogen bond and a strong resonance-assisted N-H⋯O intra-molecular hydrogen bond. In the crystal, the mol-ecules are linked by weak inter-molecular C-H⋯O inter-actions, forming zigzag chains along the b axis.

(Acetyl-acetonato)dibromido[2,2-diphenyl-hydrazin-1-ido(1-)][2,2-diphenyl-hydrazin-1-ido(2-)]molybdenum(VI).

In the title compound, [MoBr(2)(C(12)H(11)N(2))(C(12)H(10)N(2))(C(5)H(7)O(2))], the Mo(VI) atom is six-coordinated in a distorted octa-hedral geometry by two N atoms from the diphenyl-hydrazide(1-) and diphenyl-hydrazide(2-) ligands, two O atoms from a bidentate acetyl-acetonate ligand and two Br(-) ions. The mol-ecules form an inversion dimer via a pair of weak C-H⋯O hydrogen bonds and a π-π stacking inter-action with a centroid-centroid distance of 3.7401 (12) Å.